/* binder.c
 *
 * Android IPC Subsystem
 *
 * Copyright (C) 2007-2008 Google, Inc.
 *
 * This software is licensed under the terms of the GNU General Public
 * License version 2, as published by the Free Software Foundation, and
 * may be copied, distributed, and modified under those terms.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 */

/*
 * Locking overview
 *
 * There are 3 main spinlocks which must be acquired in the
 * order shown:
 *
 * 1) proc->outer_lock : protects binder_ref
 *    binder_proc_lock() and binder_proc_unlock() are
 *    used to acq/rel.
 * 2) node->lock : protects most fields of binder_node.
 *    binder_node_lock() and binder_node_unlock() are
 *    used to acq/rel
 * 3) proc->inner_lock : protects the thread and node lists
 *    (proc->threads, proc->waiting_threads, proc->nodes)
 *    and all todo lists associated with the binder_proc
 *    (proc->todo, thread->todo, proc->delivered_death and
 *    node->async_todo), as well as thread->transaction_stack
 *    binder_inner_proc_lock() and binder_inner_proc_unlock()
 *    are used to acq/rel
 *
 * Any lock under procA must never be nested under any lock at the same
 * level or below on procB.
 *
 * Functions that require a lock held on entry indicate which lock
 * in the suffix of the function name:
 *
 * foo_olocked() : requires node->outer_lock
 * foo_nlocked() : requires node->lock
 * foo_ilocked() : requires proc->inner_lock
 * foo_oilocked(): requires proc->outer_lock and proc->inner_lock
 * foo_nilocked(): requires node->lock and proc->inner_lock
 * ...
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <asm/cacheflush.h>
#include <linux/fdtable.h>
#include <linux/file.h>
#include <linux/freezer.h>
#include <linux/fs.h>
#include <linux/list.h>
#include <linux/miscdevice.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/nsproxy.h>
#include <linux/poll.h>
#include <linux/debugfs.h>
#include <linux/rbtree.h>
#include <linux/sched/signal.h>
#include <linux/sched/mm.h>
#include <linux/seq_file.h>
#include <linux/uaccess.h>
#include <linux/pid_namespace.h>
#include <linux/security.h>
#include <linux/spinlock.h>

#ifdef CONFIG_ANDROID_BINDER_IPC_32BIT
#define BINDER_IPC_32BIT 1
#endif

#include <uapi/linux/android/binder.h>
#include "binder_alloc.h"
#include "binder_trace.h"

static HLIST_HEAD(binder_deferred_list);
static DEFINE_MUTEX(binder_deferred_lock);

static HLIST_HEAD(binder_devices);
static HLIST_HEAD(binder_procs);
static DEFINE_MUTEX(binder_procs_lock);

static HLIST_HEAD(binder_dead_nodes);
static DEFINE_SPINLOCK(binder_dead_nodes_lock);

static struct dentry *binder_debugfs_dir_entry_root;
static struct dentry *binder_debugfs_dir_entry_proc;
static atomic_t binder_last_id;

#define BINDER_DEBUG_ENTRY(name) \
static int binder_##name##_open(struct inode *inode, struct file *file) \
{ \
        return single_open(file, binder_##name##_show, inode->i_private); \
} \
\
static const struct file_operations binder_##name##_fops = { \
        .owner = THIS_MODULE, \
        .open = binder_##name##_open, \
        .read = seq_read, \
        .llseek = seq_lseek, \
        .release = single_release, \
}

static int binder_proc_show(struct seq_file *m, void *unused);
BINDER_DEBUG_ENTRY(proc);

/* This is only defined in include/asm-arm/sizes.h */
#ifndef SZ_1K
#define SZ_1K                               0x400
#endif

#ifndef SZ_4M
#define SZ_4M                               0x400000
#endif

#define FORBIDDEN_MMAP_FLAGS                (VM_WRITE)

enum {
        BINDER_DEBUG_USER_ERROR             = 1U << 0,
        BINDER_DEBUG_FAILED_TRANSACTION     = 1U << 1,
        BINDER_DEBUG_DEAD_TRANSACTION       = 1U << 2,
        BINDER_DEBUG_OPEN_CLOSE             = 1U << 3,
        BINDER_DEBUG_DEAD_BINDER            = 1U << 4,
        BINDER_DEBUG_DEATH_NOTIFICATION     = 1U << 5,
        BINDER_DEBUG_READ_WRITE             = 1U << 6,
        BINDER_DEBUG_USER_REFS              = 1U << 7,
        BINDER_DEBUG_THREADS                = 1U << 8,
        BINDER_DEBUG_TRANSACTION            = 1U << 9,
        BINDER_DEBUG_TRANSACTION_COMPLETE   = 1U << 10,
        BINDER_DEBUG_FREE_BUFFER            = 1U << 11,
        BINDER_DEBUG_INTERNAL_REFS          = 1U << 12,
        BINDER_DEBUG_PRIORITY_CAP           = 1U << 13,
        BINDER_DEBUG_SPINLOCKS              = 1U << 14,
};
static uint32_t binder_debug_mask = BINDER_DEBUG_USER_ERROR |
        BINDER_DEBUG_FAILED_TRANSACTION | BINDER_DEBUG_DEAD_TRANSACTION;
module_param_named(debug_mask, binder_debug_mask, uint, 0644);

static char *binder_devices_param = CONFIG_ANDROID_BINDER_DEVICES;
module_param_named(devices, binder_devices_param, charp, 0444);

static DECLARE_WAIT_QUEUE_HEAD(binder_user_error_wait);
static int binder_stop_on_user_error;

static int binder_set_stop_on_user_error(const char *val,
                                         const struct kernel_param *kp)
{
        int ret;

        ret = param_set_int(val, kp);
        if (binder_stop_on_user_error < 2)
                wake_up(&binder_user_error_wait);
        return ret;
}
module_param_call(stop_on_user_error, binder_set_stop_on_user_error,
        param_get_int, &binder_stop_on_user_error, 0644);

#define binder_debug(mask, x...) \
        do { \
                if (binder_debug_mask & mask) \
                        pr_info(x); \
        } while (0)

#define binder_user_error(x...) \
        do { \
                if (binder_debug_mask & BINDER_DEBUG_USER_ERROR) \
                        pr_info(x); \
                if (binder_stop_on_user_error) \
                        binder_stop_on_user_error = 2; \
        } while (0)

#define to_flat_binder_object(hdr) \
        container_of(hdr, struct flat_binder_object, hdr)

#define to_binder_fd_object(hdr) container_of(hdr, struct binder_fd_object, hdr)

#define to_binder_buffer_object(hdr) \
        container_of(hdr, struct binder_buffer_object, hdr)

#define to_binder_fd_array_object(hdr) \
        container_of(hdr, struct binder_fd_array_object, hdr)

enum binder_stat_types {
        BINDER_STAT_PROC,
        BINDER_STAT_THREAD,
        BINDER_STAT_NODE,
        BINDER_STAT_REF,
        BINDER_STAT_DEATH,
        BINDER_STAT_TRANSACTION,
        BINDER_STAT_TRANSACTION_COMPLETE,
        BINDER_STAT_COUNT
};

struct binder_stats {
        atomic_t br[_IOC_NR(BR_FAILED_REPLY) + 1];
        atomic_t bc[_IOC_NR(BC_REPLY_SG) + 1];
        atomic_t obj_created[BINDER_STAT_COUNT];
        atomic_t obj_deleted[BINDER_STAT_COUNT];
};

static struct binder_stats binder_stats;

static inline void binder_stats_deleted(enum binder_stat_types type)
{
        atomic_inc(&binder_stats.obj_deleted[type]);
}

static inline void binder_stats_created(enum binder_stat_types type)
{
        atomic_inc(&binder_stats.obj_created[type]);
}

struct binder_transaction_log_entry {
        int debug_id;
        int debug_id_done;
        int call_type;
        int from_proc;
        int from_thread;
        int target_handle;
        int to_proc;
        int to_thread;
        int to_node;
        int data_size;
        int offsets_size;
        int return_error_line;
        uint32_t return_error;
        uint32_t return_error_param;
        const char *context_name;
};
struct binder_transaction_log {
        atomic_t cur;
        bool full;
        struct binder_transaction_log_entry entry[32];
};
static struct binder_transaction_log binder_transaction_log;
static struct binder_transaction_log binder_transaction_log_failed;

static struct binder_transaction_log_entry *binder_transaction_log_add(
        struct binder_transaction_log *log)
{
        struct binder_transaction_log_entry *e;
        unsigned int cur = atomic_inc_return(&log->cur);

        if (cur >= ARRAY_SIZE(log->entry))
                log->full = true;
        e = &log->entry[cur % ARRAY_SIZE(log->entry)];
        WRITE_ONCE(e->debug_id_done, 0);
        /*
         * write-barrier to synchronize access to e->debug_id_done.
         * We make sure the initialized 0 value is seen before
         * memset() other fields are zeroed by memset.
         */
        smp_wmb();
        memset(e, 0, sizeof(*e));
        return e;
}

struct binder_context {
        struct binder_node *binder_context_mgr_node;
        struct mutex context_mgr_node_lock;

        kuid_t binder_context_mgr_uid;
        const char *name;
};

struct binder_device {
        struct hlist_node hlist;
        struct miscdevice miscdev;
        struct binder_context context;
};

/**
 * struct binder_work - work enqueued on a worklist
 * @entry:             node enqueued on list
 * @type:              type of work to be performed
 *
 * There are separate work lists for proc, thread, and node (async).
 */
struct binder_work {
        struct list_head entry;

        enum {
                BINDER_WORK_TRANSACTION = 1,
                BINDER_WORK_TRANSACTION_COMPLETE,
                BINDER_WORK_RETURN_ERROR,
                BINDER_WORK_NODE,
                BINDER_WORK_DEAD_BINDER,
                BINDER_WORK_DEAD_BINDER_AND_CLEAR,
                BINDER_WORK_CLEAR_DEATH_NOTIFICATION,
        } type;
};

struct binder_error {
        struct binder_work work;
        uint32_t cmd;
};

/**
 * struct binder_node - binder node bookkeeping
 * @debug_id:             unique ID for debugging
 *                        (invariant after initialized)
 * @lock:                 lock for node fields
 * @work:                 worklist element for node work
 *                        (protected by @proc->inner_lock)
 * @rb_node:              element for proc->nodes tree
 *                        (protected by @proc->inner_lock)
 * @dead_node:            element for binder_dead_nodes list
 *                        (protected by binder_dead_nodes_lock)
 * @proc:                 binder_proc that owns this node
 *                        (invariant after initialized)
 * @refs:                 list of references on this node
 *                        (protected by @lock)
 * @internal_strong_refs: used to take strong references when
 *                        initiating a transaction
 *                        (protected by @proc->inner_lock if @proc
 *                        and by @lock)
 * @local_weak_refs:      weak user refs from local process
 *                        (protected by @proc->inner_lock if @proc
 *                        and by @lock)
 * @local_strong_refs:    strong user refs from local process
 *                        (protected by @proc->inner_lock if @proc
 *                        and by @lock)
 * @tmp_refs:             temporary kernel refs
 *                        (protected by @proc->inner_lock while @proc
 *                        is valid, and by binder_dead_nodes_lock
 *                        if @proc is NULL. During inc/dec and node release
 *                        it is also protected by @lock to provide safety
 *                        as the node dies and @proc becomes NULL)
 * @ptr:                  userspace pointer for node
 *                        (invariant, no lock needed)
 * @cookie:               userspace cookie for node
 *                        (invariant, no lock needed)
 * @has_strong_ref:       userspace notified of strong ref
 *                        (protected by @proc->inner_lock if @proc
 *                        and by @lock)
 * @pending_strong_ref:   userspace has acked notification of strong ref
 *                        (protected by @proc->inner_lock if @proc
 *                        and by @lock)
 * @has_weak_ref:         userspace notified of weak ref
 *                        (protected by @proc->inner_lock if @proc
 *                        and by @lock)
 * @pending_weak_ref:     userspace has acked notification of weak ref
 *                        (protected by @proc->inner_lock if @proc
 *                        and by @lock)
 * @has_async_transaction: async transaction to node in progress
 *                        (protected by @lock)
 * @accept_fds:           file descriptor operations supported for node
 *                        (invariant after initialized)
 * @min_priority:         minimum scheduling priority
 *                        (invariant after initialized)
 * @async_todo:           list of async work items
 *                        (protected by @proc->inner_lock)
 *
 * Bookkeeping structure for binder nodes.
 */
struct binder_node {
        int debug_id;
        spinlock_t lock;
        struct binder_work work;
        union {
                struct rb_node rb_node;
                struct hlist_node dead_node;
        };
        struct binder_proc *proc;
        struct hlist_head refs;
        int internal_strong_refs;
        int local_weak_refs;
        int local_strong_refs;
        int tmp_refs;
        binder_uintptr_t ptr;
        binder_uintptr_t cookie;
        struct {
                /*
                 * bitfield elements protected by
                 * proc inner_lock
                 */
                u8 has_strong_ref:1;
                u8 pending_strong_ref:1;
                u8 has_weak_ref:1;
                u8 pending_weak_ref:1;
        };
        struct {
                /*
                 * invariant after initialization
                 */
                u8 accept_fds:1;
                u8 min_priority;
        };
        bool has_async_transaction;
        struct list_head async_todo;
};

struct binder_ref_death {
        /**
         * @work: worklist element for death notifications
         *        (protected by inner_lock of the proc that
         *        this ref belongs to)
         */
        struct binder_work work;
        binder_uintptr_t cookie;
};

/**
 * struct binder_ref_data - binder_ref counts and id
 * @debug_id:        unique ID for the ref
 * @desc:            unique userspace handle for ref
 * @strong:          strong ref count (debugging only if not locked)
 * @weak:            weak ref count (debugging only if not locked)
 *
 * Structure to hold ref count and ref id information. Since
 * the actual ref can only be accessed with a lock, this structure
 * is used to return information about the ref to callers of
 * ref inc/dec functions.
 */
struct binder_ref_data {
        int debug_id;
        uint32_t desc;
        int strong;
        int weak;
};

/**
 * struct binder_ref - struct to track references on nodes
 * @data:        binder_ref_data containing id, handle, and current refcounts
 * @rb_node_desc: node for lookup by @data.desc in proc's rb_tree
 * @rb_node_node: node for lookup by @node in proc's rb_tree
 * @node_entry:  list entry for node->refs list in target node
 *               (protected by @node->lock)
 * @proc:        binder_proc containing ref
 * @node:        binder_node of target node. When cleaning up a
 *               ref for deletion in binder_cleanup_ref, a non-NULL
 *               @node indicates the node must be freed
 * @death:       pointer to death notification (ref_death) if requested
 *               (protected by @node->lock)
 *
 * Structure to track references from procA to target node (on procB). This
 * structure is unsafe to access without holding @proc->outer_lock.
 */
struct binder_ref {
        /* Lookups needed: */
        /*   node + proc => ref (transaction) */
        /*   desc + proc => ref (transaction, inc/dec ref) */
        /*   node => refs + procs (proc exit) */
        struct binder_ref_data data;
        struct rb_node rb_node_desc;
        struct rb_node rb_node_node;
        struct hlist_node node_entry;
        struct binder_proc *proc;
        struct binder_node *node;
        struct binder_ref_death *death;
};

enum binder_deferred_state {
        BINDER_DEFERRED_PUT_FILES    = 0x01,
        BINDER_DEFERRED_FLUSH        = 0x02,
        BINDER_DEFERRED_RELEASE      = 0x04,
};

/**
 * struct binder_proc - binder process bookkeeping
 * @proc_node:            element for binder_procs list
 * @threads:              rbtree of binder_threads in this proc
 *                        (protected by @inner_lock)
 * @nodes:                rbtree of binder nodes associated with
 *                        this proc ordered by node->ptr
 *                        (protected by @inner_lock)
 * @refs_by_desc:         rbtree of refs ordered by ref->desc
 *                        (protected by @outer_lock)
 * @refs_by_node:         rbtree of refs ordered by ref->node
 *                        (protected by @outer_lock)
 * @waiting_threads:      threads currently waiting for proc work
 *                        (protected by @inner_lock)
 * @pid                   PID of group_leader of process
 *                        (invariant after initialized)
 * @tsk                   task_struct for group_leader of process
 *                        (invariant after initialized)
 * @files                 files_struct for process
 *                        (protected by @files_lock)
 * @files_lock            mutex to protect @files
 * @deferred_work_node:   element for binder_deferred_list
 *                        (protected by binder_deferred_lock)
 * @deferred_work:        bitmap of deferred work to perform
 *                        (protected by binder_deferred_lock)
 * @is_dead:              process is dead and awaiting free
 *                        when outstanding transactions are cleaned up
 *                        (protected by @inner_lock)
 * @todo:                 list of work for this process
 *                        (protected by @inner_lock)
 * @stats:                per-process binder statistics
 *                        (atomics, no lock needed)
 * @delivered_death:      list of delivered death notification
 *                        (protected by @inner_lock)
 * @max_threads:          cap on number of binder threads
 *                        (protected by @inner_lock)
 * @requested_threads:    number of binder threads requested but not
 *                        yet started. In current implementation, can
 *                        only be 0 or 1.
 *                        (protected by @inner_lock)
 * @requested_threads_started: number binder threads started
 *                        (protected by @inner_lock)
 * @tmp_ref:              temporary reference to indicate proc is in use
 *                        (protected by @inner_lock)
 * @default_priority:     default scheduler priority
 *                        (invariant after initialized)
 * @debugfs_entry:        debugfs node
 * @alloc:                binder allocator bookkeeping
 * @context:              binder_context for this proc
 *                        (invariant after initialized)
 * @inner_lock:           can nest under outer_lock and/or node lock
 * @outer_lock:           no nesting under innor or node lock
 *                        Lock order: 1) outer, 2) node, 3) inner
 *
 * Bookkeeping structure for binder processes
 */
struct binder_proc {
        struct hlist_node proc_node;
        struct rb_root threads;
        struct rb_root nodes;
        struct rb_root refs_by_desc;
        struct rb_root refs_by_node;
        struct list_head waiting_threads;
        int pid;
        struct task_struct *tsk;
        struct files_struct *files;
        struct mutex files_lock;
        struct hlist_node deferred_work_node;
        int deferred_work;
        bool is_dead;

        struct list_head todo;
        struct binder_stats stats;
        struct list_head delivered_death;
        int max_threads;
        int requested_threads;
        int requested_threads_started;
        int tmp_ref;
        long default_priority;
        struct dentry *debugfs_entry;
        struct binder_alloc alloc;
        struct binder_context *context;
        spinlock_t inner_lock;
        spinlock_t outer_lock;
};

enum {
        BINDER_LOOPER_STATE_REGISTERED  = 0x01,
        BINDER_LOOPER_STATE_ENTERED     = 0x02,
        BINDER_LOOPER_STATE_EXITED      = 0x04,
        BINDER_LOOPER_STATE_INVALID     = 0x08,
        BINDER_LOOPER_STATE_WAITING     = 0x10,
        BINDER_LOOPER_STATE_POLL        = 0x20,
};

/**
 * struct binder_thread - binder thread bookkeeping
 * @proc:                 binder process for this thread
 *                        (invariant after initialization)
 * @rb_node:              element for proc->threads rbtree
 *                        (protected by @proc->inner_lock)
 * @waiting_thread_node:  element for @proc->waiting_threads list
 *                        (protected by @proc->inner_lock)
 * @pid:                  PID for this thread
 *                        (invariant after initialization)
 * @looper:               bitmap of looping state
 *                        (only accessed by this thread)
 * @looper_needs_return:  looping thread needs to exit driver
 *                        (no lock needed)
 * @transaction_stack:    stack of in-progress transactions for this thread
 *                        (protected by @proc->inner_lock)
 * @todo:                 list of work to do for this thread
 *                        (protected by @proc->inner_lock)
 * @process_todo:         whether work in @todo should be processed
 *                        (protected by @proc->inner_lock)
 * @return_error:         transaction errors reported by this thread
 *                        (only accessed by this thread)
 * @reply_error:          transaction errors reported by target thread
 *                        (protected by @proc->inner_lock)
 * @wait:                 wait queue for thread work
 * @stats:                per-thread statistics
 *                        (atomics, no lock needed)
 * @tmp_ref:              temporary reference to indicate thread is in use
 *                        (atomic since @proc->inner_lock cannot
 *                        always be acquired)
 * @is_dead:              thread is dead and awaiting free
 *                        when outstanding transactions are cleaned up
 *                        (protected by @proc->inner_lock)
 *
 * Bookkeeping structure for binder threads.
 */
struct binder_thread {
        struct binder_proc *proc;
        struct rb_node rb_node;
        struct list_head waiting_thread_node;
        int pid;
        int looper;              /* only modified by this thread */
        bool looper_need_return; /* can be written by other thread */
        struct binder_transaction *transaction_stack;
        struct list_head todo;
        bool process_todo;
        struct binder_error return_error;
        struct binder_error reply_error;
        wait_queue_head_t wait;
        struct binder_stats stats;
        atomic_t tmp_ref;
        bool is_dead;
};

struct binder_transaction {
        int debug_id;
        struct binder_work work;
        struct binder_thread *from;
        struct binder_transaction *from_parent;
        struct binder_proc *to_proc;
        struct binder_thread *to_thread;
        struct binder_transaction *to_parent;
        unsigned need_reply:1;
        /* unsigned is_dead:1; */       /* not used at the moment */

        struct binder_buffer *buffer;
        unsigned int    code;
        unsigned int    flags;
        long    priority;
        long    saved_priority;
        kuid_t  sender_euid;
        /**
         * @lock:  protects @from, @to_proc, and @to_thread
         *
         * @from, @to_proc, and @to_thread can be set to NULL
         * during thread teardown
         */
        spinlock_t lock;
};

/**
 * binder_proc_lock() - Acquire outer lock for given binder_proc
 * @proc:         struct binder_proc to acquire
 *
 * Acquires proc->outer_lock. Used to protect binder_ref
 * structures associated with the given proc.
 */
#define binder_proc_lock(proc) _binder_proc_lock(proc, __LINE__)
static void
_binder_proc_lock(struct binder_proc *proc, int line)
{
        binder_debug(BINDER_DEBUG_SPINLOCKS,
                     "%s: line=%d\n", __func__, line);
        spin_lock(&proc->outer_lock);
}

/**
 * binder_proc_unlock() - Release spinlock for given binder_proc
 * @proc:         struct binder_proc to acquire
 *
 * Release lock acquired via binder_proc_lock()
 */
#define binder_proc_unlock(_proc) _binder_proc_unlock(_proc, __LINE__)
static void
_binder_proc_unlock(struct binder_proc *proc, int line)
{
        binder_debug(BINDER_DEBUG_SPINLOCKS,
                     "%s: line=%d\n", __func__, line);
        spin_unlock(&proc->outer_lock);
}

/**
 * binder_inner_proc_lock() - Acquire inner lock for given binder_proc
 * @proc:         struct binder_proc to acquire
 *
 * Acquires proc->inner_lock. Used to protect todo lists
 */
#define binder_inner_proc_lock(proc) _binder_inner_proc_lock(proc, __LINE__)
static void
_binder_inner_proc_lock(struct binder_proc *proc, int line)
{
        binder_debug(BINDER_DEBUG_SPINLOCKS,
                     "%s: line=%d\n", __func__, line);
        spin_lock(&proc->inner_lock);
}

/**
 * binder_inner_proc_unlock() - Release inner lock for given binder_proc
 * @proc:         struct binder_proc to acquire
 *
 * Release lock acquired via binder_inner_proc_lock()
 */
#define binder_inner_proc_unlock(proc) _binder_inner_proc_unlock(proc, __LINE__)
static void
_binder_inner_proc_unlock(struct binder_proc *proc, int line)
{
        binder_debug(BINDER_DEBUG_SPINLOCKS,
                     "%s: line=%d\n", __func__, line);
        spin_unlock(&proc->inner_lock);
}

/**
 * binder_node_lock() - Acquire spinlock for given binder_node
 * @node:         struct binder_node to acquire
 *
 * Acquires node->lock. Used to protect binder_node fields
 */
#define binder_node_lock(node) _binder_node_lock(node, __LINE__)
static void
_binder_node_lock(struct binder_node *node, int line)
{
        binder_debug(BINDER_DEBUG_SPINLOCKS,
                     "%s: line=%d\n", __func__, line);
        spin_lock(&node->lock);
}

/**
 * binder_node_unlock() - Release spinlock for given binder_proc
 * @node:         struct binder_node to acquire
 *
 * Release lock acquired via binder_node_lock()
 */
#define binder_node_unlock(node) _binder_node_unlock(node, __LINE__)
static void
_binder_node_unlock(struct binder_node *node, int line)
{
        binder_debug(BINDER_DEBUG_SPINLOCKS,
                     "%s: line=%d\n", __func__, line);
        spin_unlock(&node->lock);
}

/**
 * binder_node_inner_lock() - Acquire node and inner locks
 * @node:         struct binder_node to acquire
 *
 * Acquires node->lock. If node->proc also acquires
 * proc->inner_lock. Used to protect binder_node fields
 */
#define binder_node_inner_lock(node) _binder_node_inner_lock(node, __LINE__)
static void
_binder_node_inner_lock(struct binder_node *node, int line)
{
        binder_debug(BINDER_DEBUG_SPINLOCKS,
                     "%s: line=%d\n", __func__, line);
        spin_lock(&node->lock);
        if (node->proc)
                binder_inner_proc_lock(node->proc);
}

/**
 * binder_node_unlock() - Release node and inner locks
 * @node:         struct binder_node to acquire
 *
 * Release lock acquired via binder_node_lock()
 */
#define binder_node_inner_unlock(node) _binder_node_inner_unlock(node, __LINE__)
static void
_binder_node_inner_unlock(struct binder_node *node, int line)
{
        struct binder_proc *proc = node->proc;

        binder_debug(BINDER_DEBUG_SPINLOCKS,
                     "%s: line=%d\n", __func__, line);
        if (proc)
                binder_inner_proc_unlock(proc);
        spin_unlock(&node->lock);
}

static bool binder_worklist_empty_ilocked(struct list_head *list)
{
        return list_empty(list);
}

/**
 * binder_worklist_empty() - Check if no items on the work list
 * @proc:       binder_proc associated with list
 * @list:       list to check
 *
 * Return: true if there are no items on list, else false
 */
static bool binder_worklist_empty(struct binder_proc *proc,
                                  struct list_head *list)
{
        bool ret;

        binder_inner_proc_lock(proc);
        ret = binder_worklist_empty_ilocked(list);
        binder_inner_proc_unlock(proc);
        return ret;
}

/**
 * binder_enqueue_work_ilocked() - Add an item to the work list
 * @work:         struct binder_work to add to list
 * @target_list:  list to add work to
 *
 * Adds the work to the specified list. Asserts that work
 * is not already on a list.
 *
 * Requires the proc->inner_lock to be held.
 */
static void
binder_enqueue_work_ilocked(struct binder_work *work,
                           struct list_head *target_list)
{
        BUG_ON(target_list == NULL);
        BUG_ON(work->entry.next && !list_empty(&work->entry));
        list_add_tail(&work->entry, target_list);
}

/**
 * binder_enqueue_deferred_thread_work_ilocked() - Add deferred thread work
 * @thread:       thread to queue work to
 * @work:         struct binder_work to add to list
 *
 * Adds the work to the todo list of the thread. Doesn't set the process_todo
 * flag, which means that (if it wasn't already set) the thread will go to
 * sleep without handling this work when it calls read.
 *
 * Requires the proc->inner_lock to be held.
 */
static void
binder_enqueue_deferred_thread_work_ilocked(struct binder_thread *thread,
                                            struct binder_work *work)
{
        binder_enqueue_work_ilocked(work, &thread->todo);
}

/**
 * binder_enqueue_thread_work_ilocked() - Add an item to the thread work list
 * @thread:       thread to queue work to
 * @work:         struct binder_work to add to list
 *
 * Adds the work to the todo list of the thread, and enables processing
 * of the todo queue.
 *
 * Requires the proc->inner_lock to be held.
 */
static void
binder_enqueue_thread_work_ilocked(struct binder_thread *thread,
                                   struct binder_work *work)
{
        binder_enqueue_work_ilocked(work, &thread->todo);
        thread->process_todo = true;
}

/**
 * binder_enqueue_thread_work() - Add an item to the thread work list
 * @thread:       thread to queue work to
 * @work:         struct binder_work to add to list
 *
 * Adds the work to the todo list of the thread, and enables processing
 * of the todo queue.
 */
static void
binder_enqueue_thread_work(struct binder_thread *thread,
                           struct binder_work *work)
{
        binder_inner_proc_lock(thread->proc);
        binder_enqueue_thread_work_ilocked(thread, work);
        binder_inner_proc_unlock(thread->proc);
}

static void
binder_dequeue_work_ilocked(struct binder_work *work)
{
        list_del_init(&work->entry);
}

/**
 * binder_dequeue_work() - Removes an item from the work list
 * @proc:         binder_proc associated with list
 * @work:         struct binder_work to remove from list
 *
 * Removes the specified work item from whatever list it is on.
 * Can safely be called if work is not on any list.
 */
static void
binder_dequeue_work(struct binder_proc *proc, struct binder_work *work)
{
        binder_inner_proc_lock(proc);
        binder_dequeue_work_ilocked(work);
        binder_inner_proc_unlock(proc);
}

static struct binder_work *binder_dequeue_work_head_ilocked(
                                        struct list_head *list)
{
        struct binder_work *w;

        w = list_first_entry_or_null(list, struct binder_work, entry);
        if (w)
                list_del_init(&w->entry);
        return w;
}

/**
 * binder_dequeue_work_head() - Dequeues the item at head of list
 * @proc:         binder_proc associated with list
 * @list:         list to dequeue head
 *
 * Removes the head of the list if there are items on the list
 *
 * Return: pointer dequeued binder_work, NULL if list was empty
 */
static struct binder_work *binder_dequeue_work_head(
                                        struct binder_proc *proc,
                                        struct list_head *list)
{
        struct binder_work *w;

        binder_inner_proc_lock(proc);
        w = binder_dequeue_work_head_ilocked(list);
        binder_inner_proc_unlock(proc);
        return w;
}

static void
binder_defer_work(struct binder_proc *proc, enum binder_deferred_state defer);
static void binder_free_thread(struct binder_thread *thread);
static void binder_free_proc(struct binder_proc *proc);
static void binder_inc_node_tmpref_ilocked(struct binder_node *node);

static int task_get_unused_fd_flags(struct binder_proc *proc, int flags)
{
        unsigned long rlim_cur;
        unsigned long irqs;
        int ret;

        mutex_lock(&proc->files_lock);
        if (proc->files == NULL) {
                ret = -ESRCH;
                goto err;
        }
        if (!lock_task_sighand(proc->tsk, &irqs)) {
                ret = -EMFILE;
                goto err;
        }
        rlim_cur = task_rlimit(proc->tsk, RLIMIT_NOFILE);
        unlock_task_sighand(proc->tsk, &irqs);

        ret = __alloc_fd(proc->files, 0, rlim_cur, flags);
err:
        mutex_unlock(&proc->files_lock);
        return ret;
}

/*
 * copied from fd_install
 */
static void task_fd_install(
        struct binder_proc *proc, unsigned int fd, struct file *file)
{
        mutex_lock(&proc->files_lock);
        if (proc->files)
                __fd_install(proc->files, fd, file);
        mutex_unlock(&proc->files_lock);
}

/*
 * copied from sys_close
 */
static long task_close_fd(struct binder_proc *proc, unsigned int fd)
{
        int retval;

        mutex_lock(&proc->files_lock);
        if (proc->files == NULL) {
                retval = -ESRCH;
                goto err;
        }
        retval = __close_fd(proc->files, fd);
        /* can't restart close syscall because file table entry was cleared */
        if (unlikely(retval == -ERESTARTSYS ||
                     retval == -ERESTARTNOINTR ||
                     retval == -ERESTARTNOHAND ||
                     retval == -ERESTART_RESTARTBLOCK))
                retval = -EINTR;
err:
        mutex_unlock(&proc->files_lock);
        return retval;
}

static bool binder_has_work_ilocked(struct binder_thread *thread,
                                    bool do_proc_work)
{
        return thread->process_todo ||
                thread->looper_need_return ||
                (do_proc_work &&
                 !binder_worklist_empty_ilocked(&thread->proc->todo));
}

static bool binder_has_work(struct binder_thread *thread, bool do_proc_work)
{
        bool has_work;

        binder_inner_proc_lock(thread->proc);
        has_work = binder_has_work_ilocked(thread, do_proc_work);
        binder_inner_proc_unlock(thread->proc);

        return has_work;
}

static bool binder_available_for_proc_work_ilocked(struct binder_thread *thread)
{
        return !thread->transaction_stack &&
                binder_worklist_empty_ilocked(&thread->todo) &&
                (thread->looper & (BINDER_LOOPER_STATE_ENTERED |
                                   BINDER_LOOPER_STATE_REGISTERED));
}

static void binder_wakeup_poll_threads_ilocked(struct binder_proc *proc,
                                               bool sync)
{
        struct rb_node *n;
        struct binder_thread *thread;

        for (n = rb_first(&proc->threads); n != NULL; n = rb_next(n)) {
                thread = rb_entry(n, struct binder_thread, rb_node);
                if (thread->looper & BINDER_LOOPER_STATE_POLL &&
                    binder_available_for_proc_work_ilocked(thread)) {
                        if (sync)
                                wake_up_interruptible_sync(&thread->wait);
                        else
                                wake_up_interruptible(&thread->wait);
                }
        }
}

/**
 * binder_select_thread_ilocked() - selects a thread for doing proc work.
 * @proc:       process to select a thread from
 *
 * Note that calling this function moves the thread off the waiting_threads
 * list, so it can only be woken up by the caller of this function, or a
 * signal. Therefore, callers *should* always wake up the thread this function
 * returns.
 *
 * Return:      If there's a thread currently waiting for process work,
 *              returns that thread. Otherwise returns NULL.
 */
static struct binder_thread *
binder_select_thread_ilocked(struct binder_proc *proc)
{
        struct binder_thread *thread;

        assert_spin_locked(&proc->inner_lock);
        thread = list_first_entry_or_null(&proc->waiting_threads,
                                          struct binder_thread,
                                          waiting_thread_node);

        if (thread)
                list_del_init(&thread->waiting_thread_node);

        return thread;
}

/**
 * binder_wakeup_thread_ilocked() - wakes up a thread for doing proc work.
 * @proc:       process to wake up a thread in
 * @thread:     specific thread to wake-up (may be NULL)
 * @sync:       whether to do a synchronous wake-up
 *
 * This function wakes up a thread in the @proc process.
 * The caller may provide a specific thread to wake-up in
 * the @thread parameter. If @thread is NULL, this function
 * will wake up threads that have called poll().
 *
 * Note that for this function to work as expected, callers
 * should first call binder_select_thread() to find a thread
 * to handle the work (if they don't have a thread already),
 * and pass the result into the @thread parameter.
 */
static void binder_wakeup_thread_ilocked(struct binder_proc *proc,
                                         struct binder_thread *thread,
                                         bool sync)
{
        assert_spin_locked(&proc->inner_lock);

        if (thread) {
                if (sync)
                        wake_up_interruptible_sync(&thread->wait);
                else
                        wake_up_interruptible(&thread->wait);
                return;
        }

        /* Didn't find a thread waiting for proc work; this can happen
         * in two scenarios:
         * 1. All threads are busy handling transactions
         *    In that case, one of those threads should call back into
         *    the kernel driver soon and pick up this work.
         * 2. Threads are using the (e)poll interface, in which case
         *    they may be blocked on the waitqueue without having been
         *    added to waiting_threads. For this case, we just iterate
         *    over all threads not handling transaction work, and
         *    wake them all up. We wake all because we don't know whether
         *    a thread that called into (e)poll is handling non-binder
         *    work currently.
         */
        binder_wakeup_poll_threads_ilocked(proc, sync);
}

static void binder_wakeup_proc_ilocked(struct binder_proc *proc)
{
        struct binder_thread *thread = binder_select_thread_ilocked(proc);

        binder_wakeup_thread_ilocked(proc, thread, /* sync = */false);
}

static void binder_set_nice(long nice)
{
        long min_nice;

        if (can_nice(current, nice)) {
                set_user_nice(current, nice);
                return;
        }
        min_nice = rlimit_to_nice(rlimit(RLIMIT_NICE));
        binder_debug(BINDER_DEBUG_PRIORITY_CAP,
                     "%d: nice value %ld not allowed use %ld instead\n",
                      current->pid, nice, min_nice);
        set_user_nice(current, min_nice);
        if (min_nice <= MAX_NICE)
                return;
        binder_user_error("%d RLIMIT_NICE not set\n", current->pid);
}

static struct binder_node *binder_get_node_ilocked(struct binder_proc *proc,
                                                   binder_uintptr_t ptr)
{
        struct rb_node *n = proc->nodes.rb_node;
        struct binder_node *node;

        assert_spin_locked(&proc->inner_lock);

        while (n) {
                node = rb_entry(n, struct binder_node, rb_node);

                if (ptr < node->ptr)
                        n = n->rb_left;
                else if (ptr > node->ptr)
                        n = n->rb_right;
                else {
                        /*
                         * take an implicit weak reference
                         * to ensure node stays alive until
                         * call to binder_put_node()
                         */
                        binder_inc_node_tmpref_ilocked(node);
                        return node;
                }
        }
        return NULL;
}

static struct binder_node *binder_get_node(struct binder_proc *proc,
                                           binder_uintptr_t ptr)
{
        struct binder_node *node;

        binder_inner_proc_lock(proc);
        node = binder_get_node_ilocked(proc, ptr);
        binder_inner_proc_unlock(proc);
        return node;
}

static struct binder_node *binder_init_node_ilocked(
                                                struct binder_proc *proc,
                                                struct binder_node *new_node,
                                                struct flat_binder_object *fp)
{
        struct rb_node **p = &proc->nodes.rb_node;
        struct rb_node *parent = NULL;
        struct binder_node *node;
        binder_uintptr_t ptr = fp ? fp->binder : 0;
        binder_uintptr_t cookie = fp ? fp->cookie : 0;
        __u32 flags = fp ? fp->flags : 0;

        assert_spin_locked(&proc->inner_lock);

        while (*p) {

                parent = *p;
                node = rb_entry(parent, struct binder_node, rb_node);

                if (ptr < node->ptr)
                        p = &(*p)->rb_left;
                else if (ptr > node->ptr)
                        p = &(*p)->rb_right;
                else {
                        /*
                         * A matching node is already in
                         * the rb tree. Abandon the init
                         * and return it.
                         */
                        binder_inc_node_tmpref_ilocked(node);
                        return node;
                }
        }
        node = new_node;
        binder_stats_created(BINDER_STAT_NODE);
        node->tmp_refs++;
        rb_link_node(&node->rb_node, parent, p);
        rb_insert_color(&node->rb_node, &proc->nodes);
        node->debug_id = atomic_inc_return(&binder_last_id);
        node->proc = proc;
        node->ptr = ptr;
        node->cookie = cookie;
        node->work.type = BINDER_WORK_NODE;
        node->min_priority = flags & FLAT_BINDER_FLAG_PRIORITY_MASK;
        node->accept_fds = !!(flags & FLAT_BINDER_FLAG_ACCEPTS_FDS);
        spin_lock_init(&node->lock);
        INIT_LIST_HEAD(&node->work.entry);
        INIT_LIST_HEAD(&node->async_todo);
        binder_debug(BINDER_DEBUG_INTERNAL_REFS,
                     "%d:%d node %d u%016llx c%016llx created\n",
                     proc->pid, current->pid, node->debug_id,
                     (u64)node->ptr, (u64)node->cookie);

        return node;
}

static struct binder_node *binder_new_node(struct binder_proc *proc,
                                           struct flat_binder_object *fp)
{
        struct binder_node *node;
        struct binder_node *new_node = kzalloc(sizeof(*node), GFP_KERNEL);

        if (!new_node)
                return NULL;
        binder_inner_proc_lock(proc);
        node = binder_init_node_ilocked(proc, new_node, fp);
        binder_inner_proc_unlock(proc);
        if (node != new_node)
                /*
                 * The node was already added by another thread
                 */
                kfree(new_node);

        return node;
}

static void binder_free_node(struct binder_node *node)
{
        kfree(node);
        binder_stats_deleted(BINDER_STAT_NODE);
}

static int binder_inc_node_nilocked(struct binder_node *node, int strong,
                                    int internal,
                                    struct list_head *target_list)
{
        struct binder_proc *proc = node->proc;

        assert_spin_locked(&node->lock);
        if (proc)
                assert_spin_locked(&proc->inner_lock);
        if (strong) {
                if (internal) {
                        if (target_list == NULL &&
                            node->internal_strong_refs == 0 &&
                            !(node->proc &&
                              node == node->proc->context->binder_context_mgr_node &&
                              node->has_strong_ref)) {
                                pr_err("invalid inc strong node for %d\n",
                                        node->debug_id);
                                return -EINVAL;
                        }
                        node->internal_strong_refs++;
                } else
                        node->local_strong_refs++;
                if (!node->has_strong_ref && target_list) {
                        binder_dequeue_work_ilocked(&node->work);
                        /*
                         * Note: this function is the only place where we queue
                         * directly to a thread->todo without using the
                         * corresponding binder_enqueue_thread_work() helper
                         * functions; in this case it's ok to not set the
                         * process_todo flag, since we know this node work will
                         * always be followed by other work that starts queue
                         * processing: in case of synchronous transactions, a
                         * BR_REPLY or BR_ERROR; in case of oneway
                         * transactions, a BR_TRANSACTION_COMPLETE.
                         */
                        binder_enqueue_work_ilocked(&node->work, target_list);
                }
        } else {
                if (!internal)
                        node->local_weak_refs++;
                if (!node->has_weak_ref && list_empty(&node->work.entry)) {
                        if (target_list == NULL) {
                                pr_err("invalid inc weak node for %d\n",
                                        node->debug_id);
                                return -EINVAL;
                        }
                        /*
                         * See comment above
                         */
                        binder_enqueue_work_ilocked(&node->work, target_list);
                }
        }
        return 0;
}

static int binder_inc_node(struct binder_node *node, int strong, int internal,
                           struct list_head *target_list)
{
        int ret;

        binder_node_inner_lock(node);
        ret = binder_inc_node_nilocked(node, strong, internal, target_list);
        binder_node_inner_unlock(node);

        return ret;
}

static bool binder_dec_node_nilocked(struct binder_node *node,
                                     int strong, int internal)
{
        struct binder_proc *proc = node->proc;

        assert_spin_locked(&node->lock);
        if (proc)
                assert_spin_locked(&proc->inner_lock);
        if (strong) {
                if (internal)
                        node->internal_strong_refs--;
                else
                        node->local_strong_refs--;
                if (node->local_strong_refs || node->internal_strong_refs)
                        return false;
        } else {
                if (!internal)
                        node->local_weak_refs--;
                if (node->local_weak_refs || node->tmp_refs ||
                                !hlist_empty(&node->refs))
                        return false;
        }

        if (proc && (node->has_strong_ref || node->has_weak_ref)) {
                if (list_empty(&node->work.entry)) {
                        binder_enqueue_work_ilocked(&node->work, &proc->todo);
                        binder_wakeup_proc_ilocked(proc);
                }
        } else {
                if (hlist_empty(&node->refs) && !node->local_strong_refs &&
                    !node->local_weak_refs && !node->tmp_refs) {
                        if (proc) {
                                binder_dequeue_work_ilocked(&node->work);
                                rb_erase(&node->rb_node, &proc->nodes);
                                binder_debug(BINDER_DEBUG_INTERNAL_REFS,
                                             "refless node %d deleted\n",
                                             node->debug_id);
                        } else {
                                BUG_ON(!list_empty(&node->work.entry));
                                spin_lock(&binder_dead_nodes_lock);
                                /*
                                 * tmp_refs could have changed so
                                 * check it again
                                 */
                                if (node->tmp_refs) {
                                        spin_unlock(&binder_dead_nodes_lock);
                                        return false;
                                }
                                hlist_del(&node->dead_node);
                                spin_unlock(&binder_dead_nodes_lock);
                                binder_debug(BINDER_DEBUG_INTERNAL_REFS,
                                             "dead node %d deleted\n",
                                             node->debug_id);
                        }
                        return true;
                }
        }
        return false;
}

static void binder_dec_node(struct binder_node *node, int strong, int internal)
{
        bool free_node;

        binder_node_inner_lock(node);
        free_node = binder_dec_node_nilocked(node, strong, internal);
        binder_node_inner_unlock(node);
        if (free_node)
                binder_free_node(node);
}

static void binder_inc_node_tmpref_ilocked(struct binder_node *node)
{
        /*
         * No call to binder_inc_node() is needed since we
         * don't need to inform userspace of any changes to
         * tmp_refs
         */
        node->tmp_refs++;
}

/**
 * binder_inc_node_tmpref() - take a temporary reference on node
 * @node:       node to reference
 *
 * Take reference on node to prevent the node from being freed
 * while referenced only by a local variable. The inner lock is
 * needed to serialize with the node work on the queue (which
 * isn't needed after the node is dead). If the node is dead
 * (node->proc is NULL), use binder_dead_nodes_lock to protect
 * node->tmp_refs against dead-node-only cases where the node
 * lock cannot be acquired (eg traversing the dead node list to
 * print nodes)
 */
static void binder_inc_node_tmpref(struct binder_node *node)
{
        binder_node_lock(node);
        if (node->proc)
                binder_inner_proc_lock(node->proc);
        else
                spin_lock(&binder_dead_nodes_lock);
        binder_inc_node_tmpref_ilocked(node);
        if (node->proc)
                binder_inner_proc_unlock(node->proc);
        else
                spin_unlock(&binder_dead_nodes_lock);
        binder_node_unlock(node);
}

/**
 * binder_dec_node_tmpref() - remove a temporary reference on node
 * @node:       node to reference
 *
 * Release temporary reference on node taken via binder_inc_node_tmpref()
 */
static void binder_dec_node_tmpref(struct binder_node *node)
{
        bool free_node;

        binder_node_inner_lock(node);
        if (!node->proc)
                spin_lock(&binder_dead_nodes_lock);
        node->tmp_refs--;
        BUG_ON(node->tmp_refs < 0);
        if (!node->proc)
                spin_unlock(&binder_dead_nodes_lock);
        /*
         * Call binder_dec_node() to check if all refcounts are 0
         * and cleanup is needed. Calling with strong=0 and internal=1
         * causes no actual reference to be released in binder_dec_node().
         * If that changes, a change is needed here too.
         */
        free_node = binder_dec_node_nilocked(node, 0, 1);
        binder_node_inner_unlock(node);
        if (free_node)
                binder_free_node(node);
}

static void binder_put_node(struct binder_node *node)
{
        binder_dec_node_tmpref(node);
}

static struct binder_ref *binder_get_ref_olocked(struct binder_proc *proc,
                                                 u32 desc, bool need_strong_ref)
{
        struct rb_node *n = proc->refs_by_desc.rb_node;
        struct binder_ref *ref;

        while (n) {
                ref = rb_entry(n, struct binder_ref, rb_node_desc);

                if (desc < ref->data.desc) {
                        n = n->rb_left;
                } else if (desc > ref->data.desc) {
                        n = n->rb_right;
                } else if (need_strong_ref && !ref->data.strong) {
                        binder_user_error("tried to use weak ref as strong ref\n");
                        return NULL;
                } else {
                        return ref;
                }
        }
        return NULL;
}

/**
 * binder_get_ref_for_node_olocked() - get the ref associated with given node
 * @proc:       binder_proc that owns the ref
 * @node:       binder_node of target
 * @new_ref:    newly allocated binder_ref to be initialized or %NULL
 *
 * Look up the ref for the given node and return it if it exists
 *
 * If it doesn't exist and the caller provides a newly allocated
 * ref, initialize the fields of the newly allocated ref and insert
 * into the given proc rb_trees and node refs list.
 *
 * Return:      the ref for node. It is possible that another thread
 *              allocated/initialized the ref first in which case the
 *              returned ref would be different than the passed-in
 *              new_ref. new_ref must be kfree'd by the caller in
 *              this case.
 */
static struct binder_ref *binder_get_ref_for_node_olocked(
                                        struct binder_proc *proc,
                                        struct binder_node *node,
                                        struct binder_ref *new_ref)
{
        struct binder_context *context = proc->context;
        struct rb_node **p = &proc->refs_by_node.rb_node;
        struct rb_node *parent = NULL;
        struct binder_ref *ref;
        struct rb_node *n;

        while (*p) {
                parent = *p;
                ref = rb_entry(parent, struct binder_ref, rb_node_node);

                if (node < ref->node)
                        p = &(*p)->rb_left;
                else if (node > ref->node)
                        p = &(*p)->rb_right;
                else
                        return ref;
        }
        if (!new_ref)
                return NULL;

        binder_stats_created(BINDER_STAT_REF);
        new_ref->data.debug_id = atomic_inc_return(&binder_last_id);
        new_ref->proc = proc;
        new_ref->node = node;
        rb_link_node(&new_ref->rb_node_node, parent, p);
        rb_insert_color(&new_ref->rb_node_node, &proc->refs_by_node);

        new_ref->data.desc = (node == context->binder_context_mgr_node) ? 0 : 1;
        for (n = rb_first(&proc->refs_by_desc); n != NULL; n = rb_next(n)) {
                ref = rb_entry(n, struct binder_ref, rb_node_desc);
                if (ref->data.desc > new_ref->data.desc)
                        break;
                new_ref->data.desc = ref->data.desc + 1;
        }

        p = &proc->refs_by_desc.rb_node;
        while (*p) {
                parent = *p;
                ref = rb_entry(parent, struct binder_ref, rb_node_desc);

                if (new_ref->data.desc < ref->data.desc)
                        p = &(*p)->rb_left;
                else if (new_ref->data.desc > ref->data.desc)
                        p = &(*p)->rb_right;
                else
                        BUG();
        }
        rb_link_node(&new_ref->rb_node_desc, parent, p);
        rb_insert_color(&new_ref->rb_node_desc, &proc->refs_by_desc);

        binder_node_lock(node);
        hlist_add_head(&new_ref->node_entry, &node->refs);

        binder_debug(BINDER_DEBUG_INTERNAL_REFS,
                     "%d new ref %d desc %d for node %d\n",
                      proc->pid, new_ref->data.debug_id, new_ref->data.desc,
                      node->debug_id);
        binder_node_unlock(node);
        return new_ref;
}

static void binder_cleanup_ref_olocked(struct binder_ref *ref)
{
        bool delete_node = false;

        binder_debug(BINDER_DEBUG_INTERNAL_REFS,
                     "%d delete ref %d desc %d for node %d\n",
                      ref->proc->pid, ref->data.debug_id, ref->data.desc,
                      ref->node->debug_id);

        rb_erase(&ref->rb_node_desc, &ref->proc->refs_by_desc);
        rb_erase(&ref->rb_node_node, &ref->proc->refs_by_node);

        binder_node_inner_lock(ref->node);
        if (ref->data.strong)
                binder_dec_node_nilocked(ref->node, 1, 1);

        hlist_del(&ref->node_entry);
        delete_node = binder_dec_node_nilocked(ref->node, 0, 1);
        binder_node_inner_unlock(ref->node);
        /*
         * Clear ref->node unless we want the caller to free the node
         */
        if (!delete_node) {
                /*
                 * The caller uses ref->node to determine
                 * whether the node needs to be freed. Clear
                 * it since the node is still alive.
                 */
                ref->node = NULL;
        }

        if (ref->death) {
                binder_debug(BINDER_DEBUG_DEAD_BINDER,
                             "%d delete ref %d desc %d has death notification\n",
                              ref->proc->pid, ref->data.debug_id,
                              ref->data.desc);
                binder_dequeue_work(ref->proc, &ref->death->work);
                binder_stats_deleted(BINDER_STAT_DEATH);
        }
        binder_stats_deleted(BINDER_STAT_REF);
}

/**
 * binder_inc_ref_olocked() - increment the ref for given handle
 * @ref:         ref to be incremented
 * @strong:      if true, strong increment, else weak
 * @target_list: list to queue node work on
 *
 * Increment the ref. @ref->proc->outer_lock must be held on entry
 *
 * Return: 0, if successful, else errno
 */
static int binder_inc_ref_olocked(struct binder_ref *ref, int strong,
                                  struct list_head *target_list)
{
        int ret;

        if (strong) {
                if (ref->data.strong == 0) {
                        ret = binder_inc_node(ref->node, 1, 1, target_list);
                        if (ret)
                                return ret;
                }
                ref->data.strong++;
        } else {
                if (ref->data.weak == 0) {
                        ret = binder_inc_node(ref->node, 0, 1, target_list);
                        if (ret)
                                return ret;
                }
                ref->data.weak++;
        }
        return 0;
}

/**
 * binder_dec_ref() - dec the ref for given handle
 * @ref:        ref to be decremented
 * @strong:     if true, strong decrement, else weak
 *
 * Decrement the ref.
 *
 * Return: true if ref is cleaned up and ready to be freed
 */
static bool binder_dec_ref_olocked(struct binder_ref *ref, int strong)
{
        if (strong) {
                if (ref->data.strong == 0) {
                        binder_user_error("%d invalid dec strong, ref %d desc %d s %d w %d\n",
                                          ref->proc->pid, ref->data.debug_id,
                                          ref->data.desc, ref->data.strong,
                                          ref->data.weak);
                        return false;
                }
                ref->data.strong--;
                if (ref->data.strong == 0)
                        binder_dec_node(ref->node, strong, 1);
        } else {
                if (ref->data.weak == 0) {
                        binder_user_error("%d invalid dec weak, ref %d desc %d s %d w %d\n",
                                          ref->proc->pid, ref->data.debug_id,
                                          ref->data.desc, ref->data.strong,
                                          ref->data.weak);
                        return false;
                }
                ref->data.weak--;
        }
        if (ref->data.strong == 0 && ref->data.weak == 0) {
                binder_cleanup_ref_olocked(ref);
                return true;
        }
        return false;
}

/**
 * binder_get_node_from_ref() - get the node from the given proc/desc
 * @proc:       proc containing the ref
 * @desc:       the handle associated with the ref
 * @need_strong_ref: if true, only return node if ref is strong
 * @rdata:      the id/refcount data for the ref
 *
 * Given a proc and ref handle, return the associated binder_node
 *
 * Return: a binder_node or NULL if not found or not strong when strong required
 */
static struct binder_node *binder_get_node_from_ref(
                struct binder_proc *proc,
                u32 desc, bool need_strong_ref,
                struct binder_ref_data *rdata)
{
        struct binder_node *node;
        struct binder_ref *ref;

        binder_proc_lock(proc);
        ref = binder_get_ref_olocked(proc, desc, need_strong_ref);
        if (!ref)
                goto err_no_ref;
        node = ref->node;
        /*
         * Take an implicit reference on the node to ensure
         * it stays alive until the call to binder_put_node()
         */
        binder_inc_node_tmpref(node);
        if (rdata)
                *rdata = ref->data;
        binder_proc_unlock(proc);

        return node;

err_no_ref:
        binder_proc_unlock(proc);
        return NULL;
}

/**
 * binder_free_ref() - free the binder_ref
 * @ref:        ref to free
 *
 * Free the binder_ref. Free the binder_node indicated by ref->node
 * (if non-NULL) and the binder_ref_death indicated by ref->death.
 */
static void binder_free_ref(struct binder_ref *ref)
{
        if (ref->node)
                binder_free_node(ref->node);
        kfree(ref->death);
        kfree(ref);
}

/**
 * binder_update_ref_for_handle() - inc/dec the ref for given handle
 * @proc:       proc containing the ref
 * @desc:       the handle associated with the ref
 * @increment:  true=inc reference, false=dec reference
 * @strong:     true=strong reference, false=weak reference
 * @rdata:      the id/refcount data for the ref
 *
 * Given a proc and ref handle, increment or decrement the ref
 * according to "increment" arg.
 *
 * Return: 0 if successful, else errno
 */
static int binder_update_ref_for_handle(struct binder_proc *proc,
                uint32_t desc, bool increment, bool strong,
                struct binder_ref_data *rdata)
{
        int ret = 0;
        struct binder_ref *ref;
        bool delete_ref = false;

        binder_proc_lock(proc);
        ref = binder_get_ref_olocked(proc, desc, strong);
        if (!ref) {
                ret = -EINVAL;
                goto err_no_ref;
        }
        if (increment)
                ret = binder_inc_ref_olocked(ref, strong, NULL);
        else
                delete_ref = binder_dec_ref_olocked(ref, strong);

        if (rdata)
                *rdata = ref->data;
        binder_proc_unlock(proc);

        if (delete_ref)
                binder_free_ref(ref);
        return ret;

err_no_ref:
        binder_proc_unlock(proc);
        return ret;
}

/**
 * binder_dec_ref_for_handle() - dec the ref for given handle
 * @proc:       proc containing the ref
 * @desc:       the handle associated with the ref
 * @strong:     true=strong reference, false=weak reference
 * @rdata:      the id/refcount data for the ref
 *
 * Just calls binder_update_ref_for_handle() to decrement the ref.
 *
 * Return: 0 if successful, else errno
 */
static int binder_dec_ref_for_handle(struct binder_proc *proc,
                uint32_t desc, bool strong, struct binder_ref_data *rdata)
{
        return binder_update_ref_for_handle(proc, desc, false, strong, rdata);
}


/**
 * binder_inc_ref_for_node() - increment the ref for given proc/node
 * @proc:        proc containing the ref
 * @node:        target node
 * @strong:      true=strong reference, false=weak reference
 * @target_list: worklist to use if node is incremented
 * @rdata:       the id/refcount data for the ref
 *
 * Given a proc and node, increment the ref. Create the ref if it
 * doesn't already exist
 *
 * Return: 0 if successful, else errno
 */
static int binder_inc_ref_for_node(struct binder_proc *proc,
                        struct binder_node *node,
                        bool strong,
                        struct list_head *target_list,
                        struct binder_ref_data *rdata)
{
        struct binder_ref *ref;
        struct binder_ref *new_ref = NULL;
        int ret = 0;

        binder_proc_lock(proc);
        ref = binder_get_ref_for_node_olocked(proc, node, NULL);
        if (!ref) {
                binder_proc_unlock(proc);
                new_ref = kzalloc(sizeof(*ref), GFP_KERNEL);
                if (!new_ref)
                        return -ENOMEM;
                binder_proc_lock(proc);
                ref = binder_get_ref_for_node_olocked(proc, node, new_ref);
        }
        ret = binder_inc_ref_olocked(ref, strong, target_list);
        *rdata = ref->data;
        binder_proc_unlock(proc);
        if (new_ref && ref != new_ref)
                /*
                 * Another thread created the ref first so
                 * free the one we allocated
                 */
                kfree(new_ref);
        return ret;
}

static void binder_pop_transaction_ilocked(struct binder_thread *target_thread,
                                           struct binder_transaction *t)
{
        BUG_ON(!target_thread);
        assert_spin_locked(&target_thread->proc->inner_lock);
        BUG_ON(target_thread->transaction_stack != t);
        BUG_ON(target_thread->transaction_stack->from != target_thread);
        target_thread->transaction_stack =
                target_thread->transaction_stack->from_parent;
        t->from = NULL;
}

/**
 * binder_thread_dec_tmpref() - decrement thread->tmp_ref
 * @thread:     thread to decrement
 *
 * A thread needs to be kept alive while being used to create or
 * handle a transaction. binder_get_txn_from() is used to safely
 * extract t->from from a binder_transaction and keep the thread
 * indicated by t->from from being freed. When done with that
 * binder_thread, this function is called to decrement the
 * tmp_ref and free if appropriate (thread has been released
 * and no transaction being processed by the driver)
 */
static void binder_thread_dec_tmpref(struct binder_thread *thread)
{
        /*
         * atomic is used to protect the counter value while
         * it cannot reach zero or thread->is_dead is false
         */
        binder_inner_proc_lock(thread->proc);
        atomic_dec(&thread->tmp_ref);
        if (thread->is_dead && !atomic_read(&thread->tmp_ref)) {
                binder_inner_proc_unlock(thread->proc);
                binder_free_thread(thread);
                return;
        }
        binder_inner_proc_unlock(thread->proc);
}

/**
 * binder_proc_dec_tmpref() - decrement proc->tmp_ref
 * @proc:       proc to decrement
 *
 * A binder_proc needs to be kept alive while being used to create or
 * handle a transaction. proc->tmp_ref is incremented when
 * creating a new transaction or the binder_proc is currently in-use
 * by threads that are being released. When done with the binder_proc,
 * this function is called to decrement the counter and free the
 * proc if appropriate (proc has been released, all threads have
 * been released and not currenly in-use to process a transaction).
 */
static void binder_proc_dec_tmpref(struct binder_proc *proc)
{
        binder_inner_proc_lock(proc);
        proc->tmp_ref--;
        if (proc->is_dead && RB_EMPTY_ROOT(&proc->threads) &&
                        !proc->tmp_ref) {
                binder_inner_proc_unlock(proc);
                binder_free_proc(proc);
                return;
        }
        binder_inner_proc_unlock(proc);
}

/**
 * binder_get_txn_from() - safely extract the "from" thread in transaction
 * @t:  binder transaction for t->from
 *
 * Atomically return the "from" thread and increment the tmp_ref
 * count for the thread to ensure it stays alive until
 * binder_thread_dec_tmpref() is called.
 *
 * Return: the value of t->from
 */
static struct binder_thread *binder_get_txn_from(
                struct binder_transaction *t)
{
        struct binder_thread *from;

        spin_lock(&t->lock);
        from = t->from;
        if (from)
                atomic_inc(&from->tmp_ref);
        spin_unlock(&t->lock);
        return from;
}

/**
 * binder_get_txn_from_and_acq_inner() - get t->from and acquire inner lock
 * @t:  binder transaction for t->from
 *
 * Same as binder_get_txn_from() except it also acquires the proc->inner_lock
 * to guarantee that the thread cannot be released while operating on it.
 * The caller must call binder_inner_proc_unlock() to release the inner lock
 * as well as call binder_dec_thread_txn() to release the reference.
 *
 * Return: the value of t->from
 */
static struct binder_thread *binder_get_txn_from_and_acq_inner(
                struct binder_transaction *t)
{
        struct binder_thread *from;

        from = binder_get_txn_from(t);
        if (!from)
                return NULL;
        binder_inner_proc_lock(from->proc);
        if (t->from) {
                BUG_ON(from != t->from);
                return from;
        }
        binder_inner_proc_unlock(from->proc);
        binder_thread_dec_tmpref(from);
        return NULL;
}

static void binder_free_transaction(struct binder_transaction *t)
{
        if (t->buffer)
                t->buffer->transaction = NULL;
        kfree(t);
        binder_stats_deleted(BINDER_STAT_TRANSACTION);
}

static void binder_send_failed_reply(struct binder_transaction *t,
                                     uint32_t error_code)
{
        struct binder_thread *target_thread;
        struct binder_transaction *next;

        BUG_ON(t->flags & TF_ONE_WAY);
        while (1) {
                target_thread = binder_get_txn_from_and_acq_inner(t);
                if (target_thread) {
                        binder_debug(BINDER_DEBUG_FAILED_TRANSACTION,
                                     "send failed reply for transaction %d to %d:%d\n",
                                      t->debug_id,
                                      target_thread->proc->pid,
                                      target_thread->pid);

                        binder_pop_transaction_ilocked(target_thread, t);
                        if (target_thread->reply_error.cmd == BR_OK) {
                                target_thread->reply_error.cmd = error_code;
                                binder_enqueue_thread_work_ilocked(
                                        target_thread,
                                        &target_thread->reply_error.work);
                                wake_up_interruptible(&target_thread->wait);
                        } else {
                                /*
                                 * Cannot get here for normal operation, but
                                 * we can if multiple synchronous transactions
                                 * are sent without blocking for responses.
                                 * Just ignore the 2nd error in this case.
                                 */
                                pr_warn("Unexpected reply error: %u\n",

                                        target_thread->reply_error.cmd);
                        }
                        binder_inner_proc_unlock(target_thread->proc);
                        binder_thread_dec_tmpref(target_thread);
                        binder_free_transaction(t);
                        return;
                }
                next = t->from_parent;

                binder_debug(BINDER_DEBUG_FAILED_TRANSACTION,
                             "send failed reply for transaction %d, target dead\n",
                             t->debug_id);

                binder_free_transaction(t);
                if (next == NULL) {
                        binder_debug(BINDER_DEBUG_DEAD_BINDER,
                                     "reply failed, no target thread at root\n");
                        return;
                }
                t = next;
                binder_debug(BINDER_DEBUG_DEAD_BINDER,
                             "reply failed, no target thread -- retry %d\n",
                              t->debug_id);
        }
}

/**
 * binder_cleanup_transaction() - cleans up undelivered transaction
 * @t:          transaction that needs to be cleaned up
 * @reason:     reason the transaction wasn't delivered
 * @error_code: error to return to caller (if synchronous call)
 */
static void binder_cleanup_transaction(struct binder_transaction *t,
                                       const char *reason,
                                       uint32_t error_code)
{
        if (t->buffer->target_node && !(t->flags & TF_ONE_WAY)) {
                binder_send_failed_reply(t, error_code);
        } else {
                binder_debug(BINDER_DEBUG_DEAD_TRANSACTION,
                        "undelivered transaction %d, %s\n",
                        t->debug_id, reason);
                binder_free_transaction(t);
        }
}

/**
 * binder_validate_object() - checks for a valid metadata object in a buffer.
 * @buffer:     binder_buffer that we're parsing.
 * @offset:     offset in the buffer at which to validate an object.
 *
 * Return:      If there's a valid metadata object at @offset in @buffer, the
 *              size of that object. Otherwise, it returns zero.
 */
static size_t binder_validate_object(struct binder_buffer *buffer, u64 offset)
{
        /* Check if we can read a header first */
        struct binder_object_header *hdr;
        size_t object_size = 0;

        if (offset > buffer->data_size - sizeof(*hdr) ||
            buffer->data_size < sizeof(*hdr) ||
            !IS_ALIGNED(offset, sizeof(u32)))
                return 0;

        /* Ok, now see if we can read a complete object. */
        hdr = (struct binder_object_header *)(buffer->data + offset);
        switch (hdr->type) {
        case BINDER_TYPE_BINDER:
        case BINDER_TYPE_WEAK_BINDER:
        case BINDER_TYPE_HANDLE:
        case BINDER_TYPE_WEAK_HANDLE:
                object_size = sizeof(struct flat_binder_object);
                break;
        case BINDER_TYPE_FD:
                object_size = sizeof(struct binder_fd_object);
                break;
        case BINDER_TYPE_PTR:
                object_size = sizeof(struct binder_buffer_object);
                break;
        case BINDER_TYPE_FDA:
                object_size = sizeof(struct binder_fd_array_object);
                break;
        default:
                return 0;
        }
        if (offset <= buffer->data_size - object_size &&
            buffer->data_size >= object_size)
                return object_size;
        else
                return 0;
}

/**
 * binder_validate_ptr() - validates binder_buffer_object in a binder_buffer.
 * @b:          binder_buffer containing the object
 * @index:      index in offset array at which the binder_buffer_object is
 *              located
 * @start:      points to the start of the offset array
 * @num_valid:  the number of valid offsets in the offset array
 *
 * Return:      If @index is within the valid range of the offset array
 *              described by @start and @num_valid, and if there's a valid
 *              binder_buffer_object at the offset found in index @index
 *              of the offset array, that object is returned. Otherwise,
 *              %NULL is returned.
 *              Note that the offset found in index @index itself is not
 *              verified; this function assumes that @num_valid elements
 *              from @start were previously verified to have valid offsets.
 */
static struct binder_buffer_object *binder_validate_ptr(struct binder_buffer *b,
                                                        binder_size_t index,
                                                        binder_size_t *start,
                                                        binder_size_t num_valid)
{
        struct binder_buffer_object *buffer_obj;
        binder_size_t *offp;

        if (index >= num_valid)
                return NULL;

        offp = start + index;
        buffer_obj = (struct binder_buffer_object *)(b->data + *offp);
        if (buffer_obj->hdr.type != BINDER_TYPE_PTR)
                return NULL;

        return buffer_obj;
}

/**
 * binder_validate_fixup() - validates pointer/fd fixups happen in order.
 * @b:                  transaction buffer
 * @objects_start       start of objects buffer
 * @buffer:             binder_buffer_object in which to fix up
 * @offset:             start offset in @buffer to fix up
 * @last_obj:           last binder_buffer_object that we fixed up in
 * @last_min_offset:    minimum fixup offset in @last_obj
 *
 * Return:              %true if a fixup in buffer @buffer at offset @offset is
 *                      allowed.
 *
 * For safety reasons, we only allow fixups inside a buffer to happen
 * at increasing offsets; additionally, we only allow fixup on the last
 * buffer object that was verified, or one of its parents.
 *
 * Example of what is allowed:
 *
 * A
 *   B (parent = A, offset = 0)
 *   C (parent = A, offset = 16)
 *     D (parent = C, offset = 0)
 *   E (parent = A, offset = 32) // min_offset is 16 (C.parent_offset)
 *
 * Examples of what is not allowed:
 *
 * Decreasing offsets within the same parent:
 * A
 *   C (parent = A, offset = 16)
 *   B (parent = A, offset = 0) // decreasing offset within A
 *
 * Referring to a parent that wasn't the last object or any of its parents:
 * A
 *   B (parent = A, offset = 0)
 *   C (parent = A, offset = 0)
 *   C (parent = A, offset = 16)
 *     D (parent = B, offset = 0) // B is not A or any of A's parents
 */
static bool binder_validate_fixup(struct binder_buffer *b,
                                  binder_size_t *objects_start,
                                  struct binder_buffer_object *buffer,
                                  binder_size_t fixup_offset,
                                  struct binder_buffer_object *last_obj,
                                  binder_size_t last_min_offset)
{
        if (!last_obj) {
                /* Nothing to fix up in */
                return false;
        }

        while (last_obj != buffer) {
                /*
                 * Safe to retrieve the parent of last_obj, since it
                 * was already previously verified by the driver.
                 */
                if ((last_obj->flags & BINDER_BUFFER_FLAG_HAS_PARENT) == 0)
                        return false;
                last_min_offset = last_obj->parent_offset + sizeof(uintptr_t);
                last_obj = (struct binder_buffer_object *)
                        (b->data + *(objects_start + last_obj->parent));
        }
        return (fixup_offset >= last_min_offset);
}

static void binder_transaction_buffer_release(struct binder_proc *proc,
                                              struct binder_buffer *buffer,
                                              binder_size_t *failed_at)
{
        binder_size_t *offp, *off_start, *off_end;
        int debug_id = buffer->debug_id;

        binder_debug(BINDER_DEBUG_TRANSACTION,
                     "%d buffer release %d, size %zd-%zd, failed at %pK\n",
                     proc->pid, buffer->debug_id,
                     buffer->data_size, buffer->offsets_size, failed_at);

        if (buffer->target_node)
                binder_dec_node(buffer->target_node, 1, 0);

        off_start = (binder_size_t *)(buffer->data +
                                      ALIGN(buffer->data_size, sizeof(void *)));
        if (failed_at)
                off_end = failed_at;
        else
                off_end = (void *)off_start + buffer->offsets_size;
        for (offp = off_start; offp < off_end; offp++) {
                struct binder_object_header *hdr;
                size_t object_size = binder_validate_object(buffer, *offp);

                if (object_size == 0) {
                        pr_err("transaction release %d bad object at offset %lld, size %zd\n",
                               debug_id, (u64)*offp, buffer->data_size);
                        continue;
                }
                hdr = (struct binder_object_header *)(buffer->data + *offp);
                switch (hdr->type) {
                case BINDER_TYPE_BINDER:
                case BINDER_TYPE_WEAK_BINDER: {
                        struct flat_binder_object *fp;
                        struct binder_node *node;

                        fp = to_flat_binder_object(hdr);
                        node = binder_get_node(proc, fp->binder);
                        if (node == NULL) {
                                pr_err("transaction release %d bad node %016llx\n",
                                       debug_id, (u64)fp->binder);
                                break;
                        }
                        binder_debug(BINDER_DEBUG_TRANSACTION,
                                     "        node %d u%016llx\n",
                                     node->debug_id, (u64)node->ptr);
                        binder_dec_node(node, hdr->type == BINDER_TYPE_BINDER,
                                        0);
                        binder_put_node(node);
                } break;
                case BINDER_TYPE_HANDLE:
                case BINDER_TYPE_WEAK_HANDLE: {
                        struct flat_binder_object *fp;
                        struct binder_ref_data rdata;
                        int ret;

                        fp = to_flat_binder_object(hdr);
                        ret = binder_dec_ref_for_handle(proc, fp->handle,
                                hdr->type == BINDER_TYPE_HANDLE, &rdata);

                        if (ret) {
                                pr_err("transaction release %d bad handle %d, ret = %d\n",
                                 debug_id, fp->handle, ret);
                                break;
                        }
                        binder_debug(BINDER_DEBUG_TRANSACTION,
                                     "        ref %d desc %d\n",
                                     rdata.debug_id, rdata.desc);
                } break;

                case BINDER_TYPE_FD: {
                        struct binder_fd_object *fp = to_binder_fd_object(hdr);

                        binder_debug(BINDER_DEBUG_TRANSACTION,
                                     "        fd %d\n", fp->fd);
                        if (failed_at)
                                task_close_fd(proc, fp->fd);
                } break;
                case BINDER_TYPE_PTR:
                        /*
                         * Nothing to do here, this will get cleaned up when the
                         * transaction buffer gets freed
                         */
                        break;
                case BINDER_TYPE_FDA: {
                        struct binder_fd_array_object *fda;
                        struct binder_buffer_object *parent;
                        uintptr_t parent_buffer;
                        u32 *fd_array;
                        size_t fd_index;
                        binder_size_t fd_buf_size;

                        fda = to_binder_fd_array_object(hdr);
                        parent = binder_validate_ptr(buffer, fda->parent,
                                                     off_start,
                                                     offp - off_start);
                        if (!parent) {
                                pr_err("transaction release %d bad parent offset\n",
                                       debug_id);
                                continue;
                        }
                        /*
                         * Since the parent was already fixed up, convert it
                         * back to kernel address space to access it
                         */
                        parent_buffer = parent->buffer -
                                binder_alloc_get_user_buffer_offset(
                                                &proc->alloc);

                        fd_buf_size = sizeof(u32) * fda->num_fds;
                        if (fda->num_fds >= SIZE_MAX / sizeof(u32)) {
                                pr_err("transaction release %d invalid number of fds (%lld)\n",
                                       debug_id, (u64)fda->num_fds);
                                continue;
                        }
                        if (fd_buf_size > parent->length ||
                            fda->parent_offset > parent->length - fd_buf_size) {
                                /* No space for all file descriptors here. */
                                pr_err("transaction release %d not enough space for %lld fds in buffer\n",
                                       debug_id, (u64)fda->num_fds);
                                continue;
                        }
                        fd_array = (u32 *)(parent_buffer + (uintptr_t)fda->parent_offset);
                        for (fd_index = 0; fd_index < fda->num_fds; fd_index++)
                                task_close_fd(proc, fd_array[fd_index]);
                } break;
                default:
                        pr_err("transaction release %d bad object type %x\n",
                                debug_id, hdr->type);
                        break;
                }
        }
}

static int binder_translate_binder(struct flat_binder_object *fp,
                                   struct binder_transaction *t,
                                   struct binder_thread *thread)
{
        struct binder_node *node;
        struct binder_proc *proc = thread->proc;
        struct binder_proc *target_proc = t->to_proc;
        struct binder_ref_data rdata;
        int ret = 0;

        node = binder_get_node(proc, fp->binder);
        if (!node) {
                node = binder_new_node(proc, fp);
                if (!node)
                        return -ENOMEM;
        }
        if (fp->cookie != node->cookie) {
                binder_user_error("%d:%d sending u%016llx node %d, cookie mismatch %016llx != %016llx\n",
                                  proc->pid, thread->pid, (u64)fp->binder,
                                  node->debug_id, (u64)fp->cookie,
                                  (u64)node->cookie);
                ret = -EINVAL;
                goto done;
        }
        if (security_binder_transfer_binder(proc->tsk, target_proc->tsk)) {
                ret = -EPERM;
                goto done;
        }

        ret = binder_inc_ref_for_node(target_proc, node,
                        fp->hdr.type == BINDER_TYPE_BINDER,
                        &thread->todo, &rdata);
        if (ret)
                goto done;

        if (fp->hdr.type == BINDER_TYPE_BINDER)
                fp->hdr.type = BINDER_TYPE_HANDLE;
        else
                fp->hdr.type = BINDER_TYPE_WEAK_HANDLE;
        fp->binder = 0;
        fp->handle = rdata.desc;
        fp->cookie = 0;

        trace_binder_transaction_node_to_ref(t, node, &rdata);
        binder_debug(BINDER_DEBUG_TRANSACTION,
                     "        node %d u%016llx -> ref %d desc %d\n",
                     node->debug_id, (u64)node->ptr,
                     rdata.debug_id, rdata.desc);
done:
        binder_put_node(node);
        return ret;
}

static int binder_translate_handle(struct flat_binder_object *fp,
                                   struct binder_transaction *t,
                                   struct binder_thread *thread)
{
        struct binder_proc *proc = thread->proc;
        struct binder_proc *target_proc = t->to_proc;
        struct binder_node *node;
        struct binder_ref_data src_rdata;
        int ret = 0;

        node = binder_get_node_from_ref(proc, fp->handle,
                        fp->hdr.type == BINDER_TYPE_HANDLE, &src_rdata);
        if (!node) {
                binder_user_error("%d:%d got transaction with invalid handle, %d\n",
                                  proc->pid, thread->pid, fp->handle);
                return -EINVAL;
        }
        if (security_binder_transfer_binder(proc->tsk, target_proc->tsk)) {
                ret = -EPERM;
                goto done;
        }

        binder_node_lock(node);
        if (node->proc == target_proc) {
                if (fp->hdr.type == BINDER_TYPE_HANDLE)
                        fp->hdr.type = BINDER_TYPE_BINDER;
                else
                        fp->hdr.type = BINDER_TYPE_WEAK_BINDER;
                fp->binder = node->ptr;
                fp->cookie = node->cookie;
                if (node->proc)
                        binder_inner_proc_lock(node->proc);
                binder_inc_node_nilocked(node,
                                         fp->hdr.type == BINDER_TYPE_BINDER,
                                         0, NULL);
                if (node->proc)
                        binder_inner_proc_unlock(node->proc);
                trace_binder_transaction_ref_to_node(t, node, &src_rdata);
                binder_debug(BINDER_DEBUG_TRANSACTION,
                             "        ref %d desc %d -> node %d u%016llx\n",
                             src_rdata.debug_id, src_rdata.desc, node->debug_id,
                             (u64)node->ptr);
                binder_node_unlock(node);
        } else {
                struct binder_ref_data dest_rdata;

                binder_node_unlock(node);
                ret = binder_inc_ref_for_node(target_proc, node,
                                fp->hdr.type == BINDER_TYPE_HANDLE,
                                NULL, &dest_rdata);
                if (ret)
                        goto done;

                fp->binder = 0;
                fp->handle = dest_rdata.desc;
                fp->cookie = 0;
                trace_binder_transaction_ref_to_ref(t, node, &src_rdata,
                                                    &dest_rdata);
                binder_debug(BINDER_DEBUG_TRANSACTION,
                             "        ref %d desc %d -> ref %d desc %d (node %d)\n",
                             src_rdata.debug_id, src_rdata.desc,
                             dest_rdata.debug_id, dest_rdata.desc,
                             node->debug_id);
        }
done:
        binder_put_node(node);
        return ret;
}

static int binder_translate_fd(int fd,
                               struct binder_transaction *t,
                               struct binder_thread *thread,
                               struct binder_transaction *in_reply_to)
{
        struct binder_proc *proc = thread->proc;
        struct binder_proc *target_proc = t->to_proc;
        int target_fd;
        struct file *file;
        int ret;
        bool target_allows_fd;

        if (in_reply_to)
                target_allows_fd = !!(in_reply_to->flags & TF_ACCEPT_FDS);
        else
                target_allows_fd = t->buffer->target_node->accept_fds;
        if (!target_allows_fd) {
                binder_user_error("%d:%d got %s with fd, %d, but target does not allow fds\n",
                                  proc->pid, thread->pid,
                                  in_reply_to ? "reply" : "transaction",
                                  fd);
                ret = -EPERM;
                goto err_fd_not_accepted;
        }

        file = fget(fd);
        if (!file) {
                binder_user_error("%d:%d got transaction with invalid fd, %d\n",
                                  proc->pid, thread->pid, fd);
                ret = -EBADF;
                goto err_fget;
        }
        ret = security_binder_transfer_file(proc->tsk, target_proc->tsk, file);
        if (ret < 0) {
                ret = -EPERM;
                goto err_security;
        }

        target_fd = task_get_unused_fd_flags(target_proc, O_CLOEXEC);
        if (target_fd < 0) {
                ret = -ENOMEM;
                goto err_get_unused_fd;
        }
        task_fd_install(target_proc, target_fd, file);
        trace_binder_transaction_fd(t, fd, target_fd);
        binder_debug(BINDER_DEBUG_TRANSACTION, "        fd %d -> %d\n",
                     fd, target_fd);

        return target_fd;

err_get_unused_fd:
err_security:
        fput(file);
err_fget:
err_fd_not_accepted:
        return ret;
}

static int binder_translate_fd_array(struct binder_fd_array_object *fda,
                                     struct binder_buffer_object *parent,
                                     struct binder_transaction *t,
                                     struct binder_thread *thread,
                                     struct binder_transaction *in_reply_to)
{
        binder_size_t fdi, fd_buf_size, num_installed_fds;
        int target_fd;
        uintptr_t parent_buffer;
        u32 *fd_array;
        struct binder_proc *proc = thread->proc;
        struct binder_proc *target_proc = t->to_proc;

        fd_buf_size = sizeof(u32) * fda->num_fds;
        if (fda->num_fds >= SIZE_MAX / sizeof(u32)) {
                binder_user_error("%d:%d got transaction with invalid number of fds (%lld)\n",
                                  proc->pid, thread->pid, (u64)fda->num_fds);
                return -EINVAL;
        }
        if (fd_buf_size > parent->length ||
            fda->parent_offset > parent->length - fd_buf_size) {
                /* No space for all file descriptors here. */
                binder_user_error("%d:%d not enough space to store %lld fds in buffer\n",
                                  proc->pid, thread->pid, (u64)fda->num_fds);
                return -EINVAL;
        }
        /*
         * Since the parent was already fixed up, convert it
         * back to the kernel address space to access it
         */
        parent_buffer = parent->buffer -
                binder_alloc_get_user_buffer_offset(&target_proc->alloc);
        fd_array = (u32 *)(parent_buffer + (uintptr_t)fda->parent_offset);
        if (!IS_ALIGNED((unsigned long)fd_array, sizeof(u32))) {
                binder_user_error("%d:%d parent offset not aligned correctly.\n",
                                  proc->pid, thread->pid);
                return -EINVAL;
        }
        for (fdi = 0; fdi < fda->num_fds; fdi++) {
                target_fd = binder_translate_fd(fd_array[fdi], t, thread,
                                                in_reply_to);
                if (target_fd < 0)
                        goto err_translate_fd_failed;
                fd_array[fdi] = target_fd;
        }
        return 0;

err_translate_fd_failed:
        /*
         * Failed to allocate fd or security error, free fds
         * installed so far.
         */
        num_installed_fds = fdi;
        for (fdi = 0; fdi < num_installed_fds; fdi++)
                task_close_fd(target_proc, fd_array[fdi]);
        return target_fd;
}

static int binder_fixup_parent(struct binder_transaction *t,
                               struct binder_thread *thread,
                               struct binder_buffer_object *bp,
                               binder_size_t *off_start,
                               binder_size_t num_valid,
                               struct binder_buffer_object *last_fixup_obj,
                               binder_size_t last_fixup_min_off)
{
        struct binder_buffer_object *parent;
        u8 *parent_buffer;
        struct binder_buffer *b = t->buffer;
        struct binder_proc *proc = thread->proc;
        struct binder_proc *target_proc = t->to_proc;

        if (!(bp->flags & BINDER_BUFFER_FLAG_HAS_PARENT))
                return 0;

        parent = binder_validate_ptr(b, bp->parent, off_start, num_valid);
        if (!parent) {
                binder_user_error("%d:%d got transaction with invalid parent offset or type\n",
                                  proc->pid, thread->pid);
                return -EINVAL;
        }

        if (!binder_validate_fixup(b, off_start,
                                   parent, bp->parent_offset,
                                   last_fixup_obj,
                                   last_fixup_min_off)) {
                binder_user_error("%d:%d got transaction with out-of-order buffer fixup\n",
                                  proc->pid, thread->pid);
                return -EINVAL;
        }

        if (parent->length < sizeof(binder_uintptr_t) ||
            bp->parent_offset > parent->length - sizeof(binder_uintptr_t)) {
                /* No space for a pointer here! */
                binder_user_error("%d:%d got transaction with invalid parent offset\n",
                                  proc->pid, thread->pid);
                return -EINVAL;
        }
        parent_buffer = (u8 *)((uintptr_t)parent->buffer -
                        binder_alloc_get_user_buffer_offset(
                                &target_proc->alloc));
        *(binder_uintptr_t *)(parent_buffer + bp->parent_offset) = bp->buffer;

        return 0;
}

/**
 * binder_proc_transaction() - sends a transaction to a process and wakes it up
 * @t:          transaction to send
 * @proc:       process to send the transaction to
 * @thread:     thread in @proc to send the transaction to (may be NULL)
 *
 * This function queues a transaction to the specified process. It will try
 * to find a thread in the target process to handle the transaction and
 * wake it up. If no thread is found, the work is queued to the proc
 * waitqueue.
 *
 * If the @thread parameter is not NULL, the transaction is always queued
 * to the waitlist of that specific thread.
 *
 * Return:      true if the transactions was successfully queued
 *              false if the target process or thread is dead
 */
static bool binder_proc_transaction(struct binder_transaction *t,
                                    struct binder_proc *proc,
                                    struct binder_thread *thread)
{
        struct binder_node *node = t->buffer->target_node;
        bool oneway = !!(t->flags & TF_ONE_WAY);
        bool pending_async = false;

        BUG_ON(!node);
        binder_node_lock(node);
        if (oneway) {
                BUG_ON(thread);
                if (node->has_async_transaction) {
                        pending_async = true;
                } else {
                        node->has_async_transaction = true;
                }
        }

        binder_inner_proc_lock(proc);

        if (proc->is_dead || (thread && thread->is_dead)) {
                binder_inner_proc_unlock(proc);
                binder_node_unlock(node);
                return false;
        }

        if (!thread && !pending_async)
                thread = binder_select_thread_ilocked(proc);

        if (thread)
                binder_enqueue_thread_work_ilocked(thread, &t->work);
        else if (!pending_async)
                binder_enqueue_work_ilocked(&t->work, &proc->todo);
        else
                binder_enqueue_work_ilocked(&t->work, &node->async_todo);

        if (!pending_async)
                binder_wakeup_thread_ilocked(proc, thread, !oneway /* sync */);

        binder_inner_proc_unlock(proc);
        binder_node_unlock(node);

        return true;
}

/**
 * binder_get_node_refs_for_txn() - Get required refs on node for txn
 * @node:         struct binder_node for which to get refs
 * @proc:         returns @node->proc if valid
 * @error:        if no @proc then returns BR_DEAD_REPLY
 *
 * User-space normally keeps the node alive when creating a transaction
 * since it has a reference to the target. The local strong ref keeps it
 * alive if the sending process dies before the target process processes
 * the transaction. If the source process is malicious or has a reference
 * counting bug, relying on the local strong ref can fail.
 *
 * Since user-space can cause the local strong ref to go away, we also take
 * a tmpref on the node to ensure it survives while we are constructing
 * the transaction. We also need a tmpref on the proc while we are
 * constructing the transaction, so we take that here as well.
 *
 * Return: The target_node with refs taken or NULL if no @node->proc is NULL.
 * Also sets @proc if valid. If the @node->proc is NULL indicating that the
 * target proc has died, @error is set to BR_DEAD_REPLY
 */
static struct binder_node *binder_get_node_refs_for_txn(
                struct binder_node *node,
                struct binder_proc **procp,
                uint32_t *error)
{
        struct binder_node *target_node = NULL;

        binder_node_inner_lock(node);
        if (node->proc) {
                target_node = node;
                binder_inc_node_nilocked(node, 1, 0, NULL);
                binder_inc_node_tmpref_ilocked(node);
                node->proc->tmp_ref++;
                *procp = node->proc;
        } else
                *error = BR_DEAD_REPLY;
        binder_node_inner_unlock(node);

        return target_node;
}

static void binder_transaction(struct binder_proc *proc,
                               struct binder_thread *thread,
                               struct binder_transaction_data *tr, int reply,
                               binder_size_t extra_buffers_size)
{
        int ret;
        struct binder_transaction *t;
        struct binder_work *tcomplete;
        binder_size_t *offp, *off_end, *off_start;
        binder_size_t off_min;
        u8 *sg_bufp, *sg_buf_end;
        struct binder_proc *target_proc = NULL;
        struct binder_thread *target_thread = NULL;
        struct binder_node *target_node = NULL;
        struct binder_transaction *in_reply_to = NULL;
        struct binder_transaction_log_entry *e;
        uint32_t return_error = 0;
        uint32_t return_error_param = 0;
        uint32_t return_error_line = 0;
        struct binder_buffer_object *last_fixup_obj = NULL;
        binder_size_t last_fixup_min_off = 0;
        struct binder_context *context = proc->context;
        int t_debug_id = atomic_inc_return(&binder_last_id);

        e = binder_transaction_log_add(&binder_transaction_log);
        e->debug_id = t_debug_id;
        e->call_type = reply ? 2 : !!(tr->flags & TF_ONE_WAY);
        e->from_proc = proc->pid;
        e->from_thread = thread->pid;
        e->target_handle = tr->target.handle;
        e->data_size = tr->data_size;
        e->offsets_size = tr->offsets_size;
        e->context_name = proc->context->name;

        if (reply) {
                binder_inner_proc_lock(proc);
                in_reply_to = thread->transaction_stack;
                if (in_reply_to == NULL) {
                        binder_inner_proc_unlock(proc);
                        binder_user_error("%d:%d got reply transaction with no transaction stack\n",
                                          proc->pid, thread->pid);
                        return_error = BR_FAILED_REPLY;
                        return_error_param = -EPROTO;
                        return_error_line = __LINE__;
                        goto err_empty_call_stack;
                }
                if (in_reply_to->to_thread != thread) {
                        spin_lock(&in_reply_to->lock);
                        binder_user_error("%d:%d got reply transaction with bad transaction stack, transaction %d has target %d:%d\n",
                                proc->pid, thread->pid, in_reply_to->debug_id,
                                in_reply_to->to_proc ?
                                in_reply_to->to_proc->pid : 0,
                                in_reply_to->to_thread ?
                                in_reply_to->to_thread->pid : 0);
                        spin_unlock(&in_reply_to->lock);
                        binder_inner_proc_unlock(proc);
                        return_error = BR_FAILED_REPLY;
                        return_error_param = -EPROTO;
                        return_error_line = __LINE__;
                        in_reply_to = NULL;
                        goto err_bad_call_stack;
                }
                thread->transaction_stack = in_reply_to->to_parent;
                binder_inner_proc_unlock(proc);
                binder_set_nice(in_reply_to->saved_priority);
                target_thread = binder_get_txn_from_and_acq_inner(in_reply_to);
                if (target_thread == NULL) {
                        return_error = BR_DEAD_REPLY;
                        return_error_line = __LINE__;
                        goto err_dead_binder;
                }
                if (target_thread->transaction_stack != in_reply_to) {
                        binder_user_error("%d:%d got reply transaction with bad target transaction stack %d, expected %d\n",
                                proc->pid, thread->pid,
                                target_thread->transaction_stack ?
                                target_thread->transaction_stack->debug_id : 0,
                                in_reply_to->debug_id);
                        binder_inner_proc_unlock(target_thread->proc);
                        return_error = BR_FAILED_REPLY;
                        return_error_param = -EPROTO;
                        return_error_line = __LINE__;
                        in_reply_to = NULL;
                        target_thread = NULL;
                        goto err_dead_binder;
                }
                target_proc = target_thread->proc;
                target_proc->tmp_ref++;
                binder_inner_proc_unlock(target_thread->proc);
        } else {
                if (tr->target.handle) {
                        struct binder_ref *ref;

                        /*
                         * There must already be a strong ref
                         * on this node. If so, do a strong
                         * increment on the node to ensure it
                         * stays alive until the transaction is
                         * done.
                         */
                        binder_proc_lock(proc);
                        ref = binder_get_ref_olocked(proc, tr->target.handle,
                                                     true);
                        if (ref) {
                                target_node = binder_get_node_refs_for_txn(
                                                ref->node, &target_proc,
                                                &return_error);
                        } else {
                                binder_user_error("%d:%d got transaction to invalid handle\n",
                                                  proc->pid, thread->pid);
                                return_error = BR_FAILED_REPLY;
                        }
                        binder_proc_unlock(proc);
                } else {
                        mutex_lock(&context->context_mgr_node_lock);
                        target_node = context->binder_context_mgr_node;
                        if (target_node)
                                target_node = binder_get_node_refs_for_txn(
                                                target_node, &target_proc,
                                                &return_error);
                        else
                                return_error = BR_DEAD_REPLY;
                        mutex_unlock(&context->context_mgr_node_lock);
                }
                if (!target_node) {
                        /*
                         * return_error is set above
                         */
                        return_error_param = -EINVAL;
                        return_error_line = __LINE__;
                        goto err_dead_binder;
                }
                e->to_node = target_node->debug_id;
                if (security_binder_transaction(proc->tsk,
                                                target_proc->tsk) < 0) {
                        return_error = BR_FAILED_REPLY;
                        return_error_param = -EPERM;
                        return_error_line = __LINE__;
                        goto err_invalid_target_handle;
                }
                binder_inner_proc_lock(proc);
                if (!(tr->flags & TF_ONE_WAY) && thread->transaction_stack) {
                        struct binder_transaction *tmp;

                        tmp = thread->transaction_stack;
                        if (tmp->to_thread != thread) {
                                spin_lock(&tmp->lock);
                                binder_user_error("%d:%d got new transaction with bad transaction stack, transaction %d has target %d:%d\n",
                                        proc->pid, thread->pid, tmp->debug_id,
                                        tmp->to_proc ? tmp->to_proc->pid : 0,
                                        tmp->to_thread ?
                                        tmp->to_thread->pid : 0);
                                spin_unlock(&tmp->lock);
                                binder_inner_proc_unlock(proc);
                                return_error = BR_FAILED_REPLY;
                                return_error_param = -EPROTO;
                                return_error_line = __LINE__;
                                goto err_bad_call_stack;
                        }
                        while (tmp) {
                                struct binder_thread *from;

                                spin_lock(&tmp->lock);
                                from = tmp->from;
                                if (from && from->proc == target_proc) {
                                        atomic_inc(&from->tmp_ref);
                                        target_thread = from;
                                        spin_unlock(&tmp->lock);
                                        break;
                                }
                                spin_unlock(&tmp->lock);
                                tmp = tmp->from_parent;
                        }
                }
                binder_inner_proc_unlock(proc);
        }
        if (target_thread)
                e->to_thread = target_thread->pid;
        e->to_proc = target_proc->pid;

        /* TODO: reuse incoming transaction for reply */
        t = kzalloc(sizeof(*t), GFP_KERNEL);
        if (t == NULL) {
                return_error = BR_FAILED_REPLY;
                return_error_param = -ENOMEM;
                return_error_line = __LINE__;
                goto err_alloc_t_failed;
        }
        binder_stats_created(BINDER_STAT_TRANSACTION);
        spin_lock_init(&t->lock);

        tcomplete = kzalloc(sizeof(*tcomplete), GFP_KERNEL);
        if (tcomplete == NULL) {
                return_error = BR_FAILED_REPLY;
                return_error_param = -ENOMEM;
                return_error_line = __LINE__;
                goto err_alloc_tcomplete_failed;
        }
        binder_stats_created(BINDER_STAT_TRANSACTION_COMPLETE);

        t->debug_id = t_debug_id;

        if (reply)
                binder_debug(BINDER_DEBUG_TRANSACTION,
                             "%d:%d BC_REPLY %d -> %d:%d, data %016llx-%016llx size %lld-%lld-%lld\n",
                             proc->pid, thread->pid, t->debug_id,
                             target_proc->pid, target_thread->pid,
                             (u64)tr->data.ptr.buffer,
                             (u64)tr->data.ptr.offsets,
                             (u64)tr->data_size, (u64)tr->offsets_size,
                             (u64)extra_buffers_size);
        else
                binder_debug(BINDER_DEBUG_TRANSACTION,
                             "%d:%d BC_TRANSACTION %d -> %d - node %d, data %016llx-%016llx size %lld-%lld-%lld\n",
                             proc->pid, thread->pid, t->debug_id,
                             target_proc->pid, target_node->debug_id,
                             (u64)tr->data.ptr.buffer,
                             (u64)tr->data.ptr.offsets,
                             (u64)tr->data_size, (u64)tr->offsets_size,
                             (u64)extra_buffers_size);

        if (!reply && !(tr->flags & TF_ONE_WAY))
                t->from = thread;
        else
                t->from = NULL;
        t->sender_euid = task_euid(proc->tsk);
        t->to_proc = target_proc;
        t->to_thread = target_thread;
        t->code = tr->code;
        t->flags = tr->flags;
        t->priority = task_nice(current);

        trace_binder_transaction(reply, t, target_node);

        t->buffer = binder_alloc_new_buf(&target_proc->alloc, tr->data_size,
                tr->offsets_size, extra_buffers_size,
                !reply && (t->flags & TF_ONE_WAY));
        if (IS_ERR(t->buffer)) {
                /*
                 * -ESRCH indicates VMA cleared. The target is dying.
                 */
                return_error_param = PTR_ERR(t->buffer);
                return_error = return_error_param == -ESRCH ?
                        BR_DEAD_REPLY : BR_FAILED_REPLY;
                return_error_line = __LINE__;
                t->buffer = NULL;
                goto err_binder_alloc_buf_failed;
        }
        t->buffer->allow_user_free = 0;
        t->buffer->debug_id = t->debug_id;
        t->buffer->transaction = t;
        t->buffer->target_node = target_node;
        trace_binder_transaction_alloc_buf(t->buffer);
        off_start = (binder_size_t *)(t->buffer->data +
                                      ALIGN(tr->data_size, sizeof(void *)));
        offp = off_start;

        if (copy_from_user(t->buffer->data, (const void __user *)(uintptr_t)
                           tr->data.ptr.buffer, tr->data_size)) {
                binder_user_error("%d:%d got transaction with invalid data ptr\n",
                                proc->pid, thread->pid);
                return_error = BR_FAILED_REPLY;
                return_error_param = -EFAULT;
                return_error_line = __LINE__;
                goto err_copy_data_failed;
        }
        if (copy_from_user(offp, (const void __user *)(uintptr_t)
                           tr->data.ptr.offsets, tr->offsets_size)) {
                binder_user_error("%d:%d got transaction with invalid offsets ptr\n",
                                proc->pid, thread->pid);
                return_error = BR_FAILED_REPLY;
                return_error_param = -EFAULT;
                return_error_line = __LINE__;
                goto err_copy_data_failed;
        }
        if (!IS_ALIGNED(tr->offsets_size, sizeof(binder_size_t))) {
                binder_user_error("%d:%d got transaction with invalid offsets size, %lld\n",
                                proc->pid, thread->pid, (u64)tr->offsets_size);
                return_error = BR_FAILED_REPLY;
                return_error_param = -EINVAL;
                return_error_line = __LINE__;
                goto err_bad_offset;

        }
        if (!IS_ALIGNED(extra_buffers_size, sizeof(u64))) {
                binder_user_error("%d:%d got transaction with unaligned buffers size, %lld\n",
                                  proc->pid, thread->pid,
                                  (u64)extra_buffers_size);
                return_error = BR_FAILED_REPLY;
                return_error_param = -EINVAL;
                return_error_line = __LINE__;
                goto err_bad_offset;
        }
        off_end = (void *)off_start + tr->offsets_size;
        sg_bufp = (u8 *)(PTR_ALIGN(off_end, sizeof(void *)));
        sg_buf_end = sg_bufp + extra_buffers_size;
        off_min = 0;
        for (; offp < off_end; offp++) {
                struct binder_object_header *hdr;
                size_t object_size = binder_validate_object(t->buffer, *offp);

                if (object_size == 0 || *offp < off_min) {
                        binder_user_error("%d:%d got transaction with invalid offset (%lld, min %lld max %lld) or object.\n",
                                          proc->pid, thread->pid, (u64)*offp,
                                          (u64)off_min,
                                          (u64)t->buffer->data_size);
                        return_error = BR_FAILED_REPLY;
                        return_error_param = -EINVAL;
                        return_error_line = __LINE__;
                        goto err_bad_offset;
                }

                hdr = (struct binder_object_header *)(t->buffer->data + *offp);
                off_min = *offp + object_size;
                switch (hdr->type) {
                case BINDER_TYPE_BINDER:
                case BINDER_TYPE_WEAK_BINDER: {
                        struct flat_binder_object *fp;

                        fp = to_flat_binder_object(hdr);
                        ret = binder_translate_binder(fp, t, thread);
                        if (ret < 0) {
                                return_error = BR_FAILED_REPLY;
                                return_error_param = ret;
                                return_error_line = __LINE__;
                                goto err_translate_failed;
                        }
                } break;
                case BINDER_TYPE_HANDLE:
                case BINDER_TYPE_WEAK_HANDLE: {
                        struct flat_binder_object *fp;

                        fp = to_flat_binder_object(hdr);
                        ret = binder_translate_handle(fp, t, thread);
                        if (ret < 0) {
                                return_error = BR_FAILED_REPLY;
                                return_error_param = ret;
                                return_error_line = __LINE__;
                                goto err_translate_failed;
                        }
                } break;

                case BINDER_TYPE_FD: {
                        struct binder_fd_object *fp = to_binder_fd_object(hdr);
                        int target_fd = binder_translate_fd(fp->fd, t, thread,
                                                            in_reply_to);

                        if (target_fd < 0) {
                                return_error = BR_FAILED_REPLY;
                                return_error_param = target_fd;
                                return_error_line = __LINE__;
                                goto err_translate_failed;
                        }
                        fp->pad_binder = 0;
                        fp->fd = target_fd;
                } break;
                case BINDER_TYPE_FDA: {
                        struct binder_fd_array_object *fda =
                                to_binder_fd_array_object(hdr);
                        struct binder_buffer_object *parent =
                                binder_validate_ptr(t->buffer, fda->parent,
                                                    off_start,
                                                    offp - off_start);
                        if (!parent) {
                                binder_user_error("%d:%d got transaction with invalid parent offset or type\n",
                                                  proc->pid, thread->pid);
                                return_error = BR_FAILED_REPLY;
                                return_error_param = -EINVAL;
                                return_error_line = __LINE__;
                                goto err_bad_parent;
                        }
                        if (!binder_validate_fixup(t->buffer, off_start,
                                                   parent, fda->parent_offset,
                                                   last_fixup_obj,
                                                   last_fixup_min_off)) {
                                binder_user_error("%d:%d got transaction with out-of-order buffer fixup\n",
                                                  proc->pid, thread->pid);
                                return_error = BR_FAILED_REPLY;
                                return_error_param = -EINVAL;
                                return_error_line = __LINE__;
                                goto err_bad_parent;
                        }
                        ret = binder_translate_fd_array(fda, parent, t, thread,
                                                        in_reply_to);
                        if (ret < 0) {
                                return_error = BR_FAILED_REPLY;
                                return_error_param = ret;
                                return_error_line = __LINE__;
                                goto err_translate_failed;
                        }
                        last_fixup_obj = parent;
                        last_fixup_min_off =
                                fda->parent_offset + sizeof(u32) * fda->num_fds;
                } break;
                case BINDER_TYPE_PTR: {
                        struct binder_buffer_object *bp =
                                to_binder_buffer_object(hdr);
                        size_t buf_left = sg_buf_end - sg_bufp;

                        if (bp->length > buf_left) {
                                binder_user_error("%d:%d got transaction with too large buffer\n",
                                                  proc->pid, thread->pid);
                                return_error = BR_FAILED_REPLY;
                                return_error_param = -EINVAL;
                                return_error_line = __LINE__;
                                goto err_bad_offset;
                        }
                        if (copy_from_user(sg_bufp,
                                           (const void __user *)(uintptr_t)
                                           bp->buffer, bp->length)) {
                                binder_user_error("%d:%d got transaction with invalid offsets ptr\n",
                                                  proc->pid, thread->pid);
                                return_error_param = -EFAULT;
                                return_error = BR_FAILED_REPLY;
                                return_error_line = __LINE__;
                                goto err_copy_data_failed;
                        }
                        /* Fixup buffer pointer to target proc address space */
                        bp->buffer = (uintptr_t)sg_bufp +
                                binder_alloc_get_user_buffer_offset(
                                                &target_proc->alloc);
                        sg_bufp += ALIGN(bp->length, sizeof(u64));

                        ret = binder_fixup_parent(t, thread, bp, off_start,
                                                  offp - off_start,
                                                  last_fixup_obj,
                                                  last_fixup_min_off);
                        if (ret < 0) {
                                return_error = BR_FAILED_REPLY;
                                return_error_param = ret;
                                return_error_line = __LINE__;
                                goto err_translate_failed;
                        }
                        last_fixup_obj = bp;
                        last_fixup_min_off = 0;
                } break;
                default:
                        binder_user_error("%d:%d got transaction with invalid object type, %x\n",
                                proc->pid, thread->pid, hdr->type);
                        return_error = BR_FAILED_REPLY;
                        return_error_param = -EINVAL;
                        return_error_line = __LINE__;
                        goto err_bad_object_type;
                }
        }
        tcomplete->type = BINDER_WORK_TRANSACTION_COMPLETE;
        t->work.type = BINDER_WORK_TRANSACTION;

        if (reply) {
                binder_enqueue_thread_work(thread, tcomplete);
                binder_inner_proc_lock(target_proc);
                if (target_thread->is_dead) {
                        binder_inner_proc_unlock(target_proc);
                        goto err_dead_proc_or_thread;
                }
                BUG_ON(t->buffer->async_transaction != 0);
                binder_pop_transaction_ilocked(target_thread, in_reply_to);
                binder_enqueue_thread_work_ilocked(target_thread, &t->work);
                binder_inner_proc_unlock(target_proc);
                wake_up_interruptible_sync(&target_thread->wait);
                binder_free_transaction(in_reply_to);
        } else if (!(t->flags & TF_ONE_WAY)) {
                BUG_ON(t->buffer->async_transaction != 0);
                binder_inner_proc_lock(proc);
                /*
                 * Defer the TRANSACTION_COMPLETE, so we don't return to
                 * userspace immediately; this allows the target process to
                 * immediately start processing this transaction, reducing
                 * latency. We will then return the TRANSACTION_COMPLETE when
                 * the target replies (or there is an error).
                 */
                binder_enqueue_deferred_thread_work_ilocked(thread, tcomplete);
                t->need_reply = 1;
                t->from_parent = thread->transaction_stack;
                thread->transaction_stack = t;
                binder_inner_proc_unlock(proc);
                if (!binder_proc_transaction(t, target_proc, target_thread)) {
                        binder_inner_proc_lock(proc);
                        binder_pop_transaction_ilocked(thread, t);
                        binder_inner_proc_unlock(proc);
                        goto err_dead_proc_or_thread;
                }
        } else {
                BUG_ON(target_node == NULL);
                BUG_ON(t->buffer->async_transaction != 1);
                binder_enqueue_thread_work(thread, tcomplete);
                if (!binder_proc_transaction(t, target_proc, NULL))
                        goto err_dead_proc_or_thread;
        }
        if (target_thread)
                binder_thread_dec_tmpref(target_thread);
        binder_proc_dec_tmpref(target_proc);
        if (target_node)
                binder_dec_node_tmpref(target_node);
        /*
         * write barrier to synchronize with initialization
         * of log entry
         */
        smp_wmb();
        WRITE_ONCE(e->debug_id_done, t_debug_id);
        return;

err_dead_proc_or_thread:
        return_error = BR_DEAD_REPLY;
        return_error_line = __LINE__;
        binder_dequeue_work(proc, tcomplete);
err_translate_failed:
err_bad_object_type:
err_bad_offset:
err_bad_parent:
err_copy_data_failed:
        trace_binder_transaction_failed_buffer_release(t->buffer);
        binder_transaction_buffer_release(target_proc, t->buffer, offp);
        if (target_node)
                binder_dec_node_tmpref(target_node);
        target_node = NULL;
        t->buffer->transaction = NULL;
        binder_alloc_free_buf(&target_proc->alloc, t->buffer);
err_binder_alloc_buf_failed:
        kfree(tcomplete);
        binder_stats_deleted(BINDER_STAT_TRANSACTION_COMPLETE);
err_alloc_tcomplete_failed:
        kfree(t);
        binder_stats_deleted(BINDER_STAT_TRANSACTION);
err_alloc_t_failed:
err_bad_call_stack:
err_empty_call_stack:
err_dead_binder:
err_invalid_target_handle:
        if (target_thread)
                binder_thread_dec_tmpref(target_thread);
        if (target_proc)
                binder_proc_dec_tmpref(target_proc);
        if (target_node) {
                binder_dec_node(target_node, 1, 0);
                binder_dec_node_tmpref(target_node);
        }

        binder_debug(BINDER_DEBUG_FAILED_TRANSACTION,
                     "%d:%d transaction failed %d/%d, size %lld-%lld line %d\n",
                     proc->pid, thread->pid, return_error, return_error_param,
                     (u64)tr->data_size, (u64)tr->offsets_size,
                     return_error_line);

        {
                struct binder_transaction_log_entry *fe;

                e->return_error = return_error;
                e->return_error_param = return_error_param;
                e->return_error_line = return_error_line;
                fe = binder_transaction_log_add(&binder_transaction_log_failed);
                *fe = *e;
                /*
                 * write barrier to synchronize with initialization
                 * of log entry
                 */
                smp_wmb();
                WRITE_ONCE(e->debug_id_done, t_debug_id);
                WRITE_ONCE(fe->debug_id_done, t_debug_id);
        }

        BUG_ON(thread->return_error.cmd != BR_OK);
        if (in_reply_to) {
                thread->return_error.cmd = BR_TRANSACTION_COMPLETE;
                binder_enqueue_thread_work(thread, &thread->return_error.work);
                binder_send_failed_reply(in_reply_to, return_error);
        } else {
                thread->return_error.cmd = return_error;
                binder_enqueue_thread_work(thread, &thread->return_error.work);
        }
}

static int binder_thread_write(struct binder_proc *proc,
                        struct binder_thread *thread,
                        binder_uintptr_t binder_buffer, size_t size,
                        binder_size_t *consumed)
{
        uint32_t cmd;
        struct binder_context *context = proc->context;
        void __user *buffer = (void __user *)(uintptr_t)binder_buffer;
        void __user *ptr = buffer + *consumed;
        void __user *end = buffer + size;

        while (ptr < end && thread->return_error.cmd == BR_OK) {
                int ret;

                if (get_user(cmd, (uint32_t __user *)ptr))
                        return -EFAULT;
                ptr += sizeof(uint32_t);
                trace_binder_command(cmd);
                if (_IOC_NR(cmd) < ARRAY_SIZE(binder_stats.bc)) {
                        atomic_inc(&binder_stats.bc[_IOC_NR(cmd)]);
                        atomic_inc(&proc->stats.bc[_IOC_NR(cmd)]);
                        atomic_inc(&thread->stats.bc[_IOC_NR(cmd)]);
                }
                switch (cmd) {
                case BC_INCREFS:
                case BC_ACQUIRE:
                case BC_RELEASE:
                case BC_DECREFS: {
                        uint32_t target;
                        const char *debug_string;
                        bool strong = cmd == BC_ACQUIRE || cmd == BC_RELEASE;
                        bool increment = cmd == BC_INCREFS || cmd == BC_ACQUIRE;
                        struct binder_ref_data rdata;

                        if (get_user(target, (uint32_t __user *)ptr))
                                return -EFAULT;

                        ptr += sizeof(uint32_t);
                        ret = -1;
                        if (increment && !target) {
                                struct binder_node *ctx_mgr_node;
                                mutex_lock(&context->context_mgr_node_lock);
                                ctx_mgr_node = context->binder_context_mgr_node;
                                if (ctx_mgr_node)
                                        ret = binder_inc_ref_for_node(
                                                        proc, ctx_mgr_node,
                                                        strong, NULL, &rdata);
                                mutex_unlock(&context->context_mgr_node_lock);
                        }
                        if (ret)
                                ret = binder_update_ref_for_handle(
                                                proc, target, increment, strong,
                                                &rdata);
                        if (!ret && rdata.desc != target) {
                                binder_user_error("%d:%d tried to acquire reference to desc %d, got %d instead\n",
                                        proc->pid, thread->pid,
                                        target, rdata.desc);
                        }
                        switch (cmd) {
                        case BC_INCREFS:
                                debug_string = "IncRefs";
                                break;
                        case BC_ACQUIRE:
                                debug_string = "Acquire";
                                break;
                        case BC_RELEASE:
                                debug_string = "Release";
                                break;
                        case BC_DECREFS:
                        default:
                                debug_string = "DecRefs";
                                break;
                        }
                        if (ret) {
                                binder_user_error("%d:%d %s %d refcount change on invalid ref %d ret %d\n",
                                        proc->pid, thread->pid, debug_string,
                                        strong, target, ret);
                                break;
                        }
                        binder_debug(BINDER_DEBUG_USER_REFS,
                                     "%d:%d %s ref %d desc %d s %d w %d\n",
                                     proc->pid, thread->pid, debug_string,
                                     rdata.debug_id, rdata.desc, rdata.strong,
                                     rdata.weak);
                        break;
                }
                case BC_INCREFS_DONE:
                case BC_ACQUIRE_DONE: {
                        binder_uintptr_t node_ptr;
                        binder_uintptr_t cookie;
                        struct binder_node *node;
                        bool free_node;

                        if (get_user(node_ptr, (binder_uintptr_t __user *)ptr))
                                return -EFAULT;
                        ptr += sizeof(binder_uintptr_t);
                        if (get_user(cookie, (binder_uintptr_t __user *)ptr))
                                return -EFAULT;
                        ptr += sizeof(binder_uintptr_t);
                        node = binder_get_node(proc, node_ptr);
                        if (node == NULL) {
                                binder_user_error("%d:%d %s u%016llx no match\n",
                                        proc->pid, thread->pid,
                                        cmd == BC_INCREFS_DONE ?
                                        "BC_INCREFS_DONE" :
                                        "BC_ACQUIRE_DONE",
                                        (u64)node_ptr);
                                break;
                        }
                        if (cookie != node->cookie) {
                                binder_user_error("%d:%d %s u%016llx node %d cookie mismatch %016llx != %016llx\n",
                                        proc->pid, thread->pid,
                                        cmd == BC_INCREFS_DONE ?
                                        "BC_INCREFS_DONE" : "BC_ACQUIRE_DONE",
                                        (u64)node_ptr, node->debug_id,
                                        (u64)cookie, (u64)node->cookie);
                                binder_put_node(node);
                                break;
                        }
                        binder_node_inner_lock(node);
                        if (cmd == BC_ACQUIRE_DONE) {
                                if (node->pending_strong_ref == 0) {
                                        binder_user_error("%d:%d BC_ACQUIRE_DONE node %d has no pending acquire request\n",
                                                proc->pid, thread->pid,
                                                node->debug_id);
                                        binder_node_inner_unlock(node);
                                        binder_put_node(node);
                                        break;
                                }
                                node->pending_strong_ref = 0;
                        } else {
                                if (node->pending_weak_ref == 0) {
                                        binder_user_error("%d:%d BC_INCREFS_DONE node %d has no pending increfs request\n",
                                                proc->pid, thread->pid,
                                                node->debug_id);
                                        binder_node_inner_unlock(node);
                                        binder_put_node(node);
                                        break;
                                }
                                node->pending_weak_ref = 0;
                        }
                        free_node = binder_dec_node_nilocked(node,
                                        cmd == BC_ACQUIRE_DONE, 0);
                        WARN_ON(free_node);
                        binder_debug(BINDER_DEBUG_USER_REFS,
                                     "%d:%d %s node %d ls %d lw %d tr %d\n",
                                     proc->pid, thread->pid,
                                     cmd == BC_INCREFS_DONE ? "BC_INCREFS_DONE" : "BC_ACQUIRE_DONE",
                                     node->debug_id, node->local_strong_refs,
                                     node->local_weak_refs, node->tmp_refs);
                        binder_node_inner_unlock(node);
                        binder_put_node(node);
                        break;
                }
                case BC_ATTEMPT_ACQUIRE:
                        pr_err("BC_ATTEMPT_ACQUIRE not supported\n");
                        return -EINVAL;
                case BC_ACQUIRE_RESULT:
                        pr_err("BC_ACQUIRE_RESULT not supported\n");
                        return -EINVAL;

                case BC_FREE_BUFFER: {
                        binder_uintptr_t data_ptr;
                        struct binder_buffer *buffer;

                        if (get_user(data_ptr, (binder_uintptr_t __user *)ptr))
                                return -EFAULT;
                        ptr += sizeof(binder_uintptr_t);

                        buffer = binder_alloc_prepare_to_free(&proc->alloc,
                                                              data_ptr);
                        if (buffer == NULL) {
                                binder_user_error("%d:%d BC_FREE_BUFFER u%016llx no match\n",
                                        proc->pid, thread->pid, (u64)data_ptr);
                                break;
                        }
                        if (!buffer->allow_user_free) {
                                binder_user_error("%d:%d BC_FREE_BUFFER u%016llx matched unreturned buffer\n",
                                        proc->pid, thread->pid, (u64)data_ptr);
                                break;
                        }
                        binder_debug(BINDER_DEBUG_FREE_BUFFER,
                                     "%d:%d BC_FREE_BUFFER u%016llx found buffer %d for %s transaction\n",
                                     proc->pid, thread->pid, (u64)data_ptr,
                                     buffer->debug_id,
                                     buffer->transaction ? "active" : "finished");

                        if (buffer->transaction) {
                                buffer->transaction->buffer = NULL;
                                buffer->transaction = NULL;
                        }
                        if (buffer->async_transaction && buffer->target_node) {
                                struct binder_node *buf_node;
                                struct binder_work *w;

                                buf_node = buffer->target_node;
                                binder_node_inner_lock(buf_node);
                                BUG_ON(!buf_node->has_async_transaction);
                                BUG_ON(buf_node->proc != proc);
                                w = binder_dequeue_work_head_ilocked(
                                                &buf_node->async_todo);
                                if (!w) {
                                        buf_node->has_async_transaction = false;
                                } else {
                                        binder_enqueue_work_ilocked(
                                                        w, &proc->todo);
                                        binder_wakeup_proc_ilocked(proc);
                                }
                                binder_node_inner_unlock(buf_node);
                        }
                        trace_binder_transaction_buffer_release(buffer);
                        binder_transaction_buffer_release(proc, buffer, NULL);
                        binder_alloc_free_buf(&proc->alloc, buffer);
                        break;
                }

                case BC_TRANSACTION_SG:
                case BC_REPLY_SG: {
                        struct binder_transaction_data_sg tr;

                        if (copy_from_user(&tr, ptr, sizeof(tr)))
                                return -EFAULT;
                        ptr += sizeof(tr);
                        binder_transaction(proc, thread, &tr.transaction_data,
                                           cmd == BC_REPLY_SG, tr.buffers_size);
                        break;
                }
                case BC_TRANSACTION:
                case BC_REPLY: {
                        struct binder_transaction_data tr;

                        if (copy_from_user(&tr, ptr, sizeof(tr)))
                                return -EFAULT;
                        ptr += sizeof(tr);
                        binder_transaction(proc, thread, &tr,
                                           cmd == BC_REPLY, 0);
                        break;
                }

                case BC_REGISTER_LOOPER:
                        binder_debug(BINDER_DEBUG_THREADS,
                                     "%d:%d BC_REGISTER_LOOPER\n",
                                     proc->pid, thread->pid);
                        binder_inner_proc_lock(proc);
                        if (thread->looper & BINDER_LOOPER_STATE_ENTERED) {
                                thread->looper |= BINDER_LOOPER_STATE_INVALID;
                                binder_user_error("%d:%d ERROR: BC_REGISTER_LOOPER called after BC_ENTER_LOOPER\n",
                                        proc->pid, thread->pid);
                        } else if (proc->requested_threads == 0) {
                                thread->looper |= BINDER_LOOPER_STATE_INVALID;
                                binder_user_error("%d:%d ERROR: BC_REGISTER_LOOPER called without request\n",
                                        proc->pid, thread->pid);
                        } else {
                                proc->requested_threads--;
                                proc->requested_threads_started++;
                        }
                        thread->looper |= BINDER_LOOPER_STATE_REGISTERED;
                        binder_inner_proc_unlock(proc);
                        break;
                case BC_ENTER_LOOPER:
                        binder_debug(BINDER_DEBUG_THREADS,
                                     "%d:%d BC_ENTER_LOOPER\n",
                                     proc->pid, thread->pid);
                        if (thread->looper & BINDER_LOOPER_STATE_REGISTERED) {
                                thread->looper |= BINDER_LOOPER_STATE_INVALID;
                                binder_user_error("%d:%d ERROR: BC_ENTER_LOOPER called after BC_REGISTER_LOOPER\n",
                                        proc->pid, thread->pid);
                        }
                        thread->looper |= BINDER_LOOPER_STATE_ENTERED;
                        break;
                case BC_EXIT_LOOPER:
                        binder_debug(BINDER_DEBUG_THREADS,
                                     "%d:%d BC_EXIT_LOOPER\n",
                                     proc->pid, thread->pid);
                        thread->looper |= BINDER_LOOPER_STATE_EXITED;
                        break;

                case BC_REQUEST_DEATH_NOTIFICATION:
                case BC_CLEAR_DEATH_NOTIFICATION: {
                        uint32_t target;
                        binder_uintptr_t cookie;
                        struct binder_ref *ref;
                        struct binder_ref_death *death = NULL;

                        if (get_user(target, (uint32_t __user *)ptr))
                                return -EFAULT;
                        ptr += sizeof(uint32_t);
                        if (get_user(cookie, (binder_uintptr_t __user *)ptr))
                                return -EFAULT;
                        ptr += sizeof(binder_uintptr_t);
                        if (cmd == BC_REQUEST_DEATH_NOTIFICATION) {
                                /*
                                 * Allocate memory for death notification
                                 * before taking lock
                                 */
                                death = kzalloc(sizeof(*death), GFP_KERNEL);
                                if (death == NULL) {
                                        WARN_ON(thread->return_error.cmd !=
                                                BR_OK);
                                        thread->return_error.cmd = BR_ERROR;
                                        binder_enqueue_thread_work(
                                                thread,
                                                &thread->return_error.work);
                                        binder_debug(
                                                BINDER_DEBUG_FAILED_TRANSACTION,
                                                "%d:%d BC_REQUEST_DEATH_NOTIFICATION failed\n",
                                                proc->pid, thread->pid);
                                        break;
                                }
                        }
                        binder_proc_lock(proc);
                        ref = binder_get_ref_olocked(proc, target, false);
                        if (ref == NULL) {
                                binder_user_error("%d:%d %s invalid ref %d\n",
                                        proc->pid, thread->pid,
                                        cmd == BC_REQUEST_DEATH_NOTIFICATION ?
                                        "BC_REQUEST_DEATH_NOTIFICATION" :
                                        "BC_CLEAR_DEATH_NOTIFICATION",
                                        target);
                                binder_proc_unlock(proc);
                                kfree(death);
                                break;
                        }

                        binder_debug(BINDER_DEBUG_DEATH_NOTIFICATION,
                                     "%d:%d %s %016llx ref %d desc %d s %d w %d for node %d\n",
                                     proc->pid, thread->pid,
                                     cmd == BC_REQUEST_DEATH_NOTIFICATION ?
                                     "BC_REQUEST_DEATH_NOTIFICATION" :
                                     "BC_CLEAR_DEATH_NOTIFICATION",
                                     (u64)cookie, ref->data.debug_id,
                                     ref->data.desc, ref->data.strong,
                                     ref->data.weak, ref->node->debug_id);

                        binder_node_lock(ref->node);
                        if (cmd == BC_REQUEST_DEATH_NOTIFICATION) {
                                if (ref->death) {
                                        binder_user_error("%d:%d BC_REQUEST_DEATH_NOTIFICATION death notification already set\n",
                                                proc->pid, thread->pid);
                                        binder_node_unlock(ref->node);
                                        binder_proc_unlock(proc);
                                        kfree(death);
                                        break;
                                }
                                binder_stats_created(BINDER_STAT_DEATH);
                                INIT_LIST_HEAD(&death->work.entry);
                                death->cookie = cookie;
                                ref->death = death;
                                if (ref->node->proc == NULL) {
                                        ref->death->work.type = BINDER_WORK_DEAD_BINDER;

                                        binder_inner_proc_lock(proc);
                                        binder_enqueue_work_ilocked(
                                                &ref->death->work, &proc->todo);
                                        binder_wakeup_proc_ilocked(proc);
                                        binder_inner_proc_unlock(proc);
                                }
                        } else {
                                if (ref->death == NULL) {
                                        binder_user_error("%d:%d BC_CLEAR_DEATH_NOTIFICATION death notification not active\n",
                                                proc->pid, thread->pid);
                                        binder_node_unlock(ref->node);
                                        binder_proc_unlock(proc);
                                        break;
                                }
                                death = ref->death;
                                if (death->cookie != cookie) {
                                        binder_user_error("%d:%d BC_CLEAR_DEATH_NOTIFICATION death notification cookie mismatch %016llx != %016llx\n",
                                                proc->pid, thread->pid,
                                                (u64)death->cookie,
                                                (u64)cookie);
                                        binder_node_unlock(ref->node);
                                        binder_proc_unlock(proc);
                                        break;
                                }
                                ref->death = NULL;
                                binder_inner_proc_lock(proc);
                                if (list_empty(&death->work.entry)) {
                                        death->work.type = BINDER_WORK_CLEAR_DEATH_NOTIFICATION;
                                        if (thread->looper &
                                            (BINDER_LOOPER_STATE_REGISTERED |
                                             BINDER_LOOPER_STATE_ENTERED))
                                                binder_enqueue_thread_work_ilocked(
                                                                thread,
                                                                &death->work);
                                        else {
                                                binder_enqueue_work_ilocked(
                                                                &death->work,
                                                                &proc->todo);
                                                binder_wakeup_proc_ilocked(
                                                                proc);
                                        }
                                } else {
                                        BUG_ON(death->work.type != BINDER_WORK_DEAD_BINDER);
                                        death->work.type = BINDER_WORK_DEAD_BINDER_AND_CLEAR;
                                }
                                binder_inner_proc_unlock(proc);
                        }
                        binder_node_unlock(ref->node);
                        binder_proc_unlock(proc);
                } break;
                case BC_DEAD_BINDER_DONE: {
                        struct binder_work *w;
                        binder_uintptr_t cookie;
                        struct binder_ref_death *death = NULL;

                        if (get_user(cookie, (binder_uintptr_t __user *)ptr))
                                return -EFAULT;

                        ptr += sizeof(cookie);
                        binder_inner_proc_lock(proc);
                        list_for_each_entry(w, &proc->delivered_death,
                                            entry) {
                                struct binder_ref_death *tmp_death =
                                        container_of(w,
                                                     struct binder_ref_death,
                                                     work);

                                if (tmp_death->cookie == cookie) {
                                        death = tmp_death;
                                        break;
                                }
                        }
                        binder_debug(BINDER_DEBUG_DEAD_BINDER,
                                     "%d:%d BC_DEAD_BINDER_DONE %016llx found %pK\n",
                                     proc->pid, thread->pid, (u64)cookie,
                                     death);
                        if (death == NULL) {
                                binder_user_error("%d:%d BC_DEAD_BINDER_DONE %016llx not found\n",
                                        proc->pid, thread->pid, (u64)cookie);
                                binder_inner_proc_unlock(proc);
                                break;
                        }
                        binder_dequeue_work_ilocked(&death->work);
                        if (death->work.type == BINDER_WORK_DEAD_BINDER_AND_CLEAR) {
                                death->work.type = BINDER_WORK_CLEAR_DEATH_NOTIFICATION;
                                if (thread->looper &
                                        (BINDER_LOOPER_STATE_REGISTERED |
                                         BINDER_LOOPER_STATE_ENTERED))
                                        binder_enqueue_thread_work_ilocked(
                                                thread, &death->work);
                                else {
                                        binder_enqueue_work_ilocked(
                                                        &death->work,
                                                        &proc->todo);
                                        binder_wakeup_proc_ilocked(proc);
                                }
                        }
                        binder_inner_proc_unlock(proc);
                } break;

                default:
                        pr_err("%d:%d unknown command %d\n",
                               proc->pid, thread->pid, cmd);
                        return -EINVAL;
                }
                *consumed = ptr - buffer;
        }
        return 0;
}

static void binder_stat_br(struct binder_proc *proc,
                           struct binder_thread *thread, uint32_t cmd)
{
        trace_binder_return(cmd);
        if (_IOC_NR(cmd) < ARRAY_SIZE(binder_stats.br)) {
                atomic_inc(&binder_stats.br[_IOC_NR(cmd)]);
                atomic_inc(&proc->stats.br[_IOC_NR(cmd)]);
                atomic_inc(&thread->stats.br[_IOC_NR(cmd)]);
        }
}

static int binder_put_node_cmd(struct binder_proc *proc,
                               struct binder_thread *thread,
                               void __user **ptrp,
                               binder_uintptr_t node_ptr,
                               binder_uintptr_t node_cookie,
                               int node_debug_id,
                               uint32_t cmd, const char *cmd_name)
{
        void __user *ptr = *ptrp;

        if (put_user(cmd, (uint32_t __user *)ptr))
                return -EFAULT;
        ptr += sizeof(uint32_t);

        if (put_user(node_ptr, (binder_uintptr_t __user *)ptr))
                return -EFAULT;
        ptr += sizeof(binder_uintptr_t);

        if (put_user(node_cookie, (binder_uintptr_t __user *)ptr))
                return -EFAULT;
        ptr += sizeof(binder_uintptr_t);

        binder_stat_br(proc, thread, cmd);
        binder_debug(BINDER_DEBUG_USER_REFS, "%d:%d %s %d u%016llx c%016llx\n",
                     proc->pid, thread->pid, cmd_name, node_debug_id,
                     (u64)node_ptr, (u64)node_cookie);

        *ptrp = ptr;
        return 0;
}

static int binder_wait_for_work(struct binder_thread *thread,
                                bool do_proc_work)
{
        DEFINE_WAIT(wait);
        struct binder_proc *proc = thread->proc;
        int ret = 0;

        freezer_do_not_count();
        binder_inner_proc_lock(proc);
        for (;;) {
                prepare_to_wait(&thread->wait, &wait, TASK_INTERRUPTIBLE);
                if (binder_has_work_ilocked(thread, do_proc_work))
                        break;
                if (do_proc_work)
                        list_add(&thread->waiting_thread_node,
                                 &proc->waiting_threads);
                binder_inner_proc_unlock(proc);
                schedule();
                binder_inner_proc_lock(proc);
                list_del_init(&thread->waiting_thread_node);
                if (signal_pending(current)) {
                        ret = -ERESTARTSYS;
                        break;
                }
        }
        finish_wait(&thread->wait, &wait);
        binder_inner_proc_unlock(proc);
        freezer_count();

        return ret;
}

static int binder_thread_read(struct binder_proc *proc,
                              struct binder_thread *thread,
                              binder_uintptr_t binder_buffer, size_t size,
                              binder_size_t *consumed, int non_block)
{
        void __user *buffer = (void __user *)(uintptr_t)binder_buffer;
        void __user *ptr = buffer + *consumed;
        void __user *end = buffer + size;

        int ret = 0;
        int wait_for_proc_work;

        if (*consumed == 0) {
                if (put_user(BR_NOOP, (uint32_t __user *)ptr))
                        return -EFAULT;
                ptr += sizeof(uint32_t);
        }

retry:
        binder_inner_proc_lock(proc);
        wait_for_proc_work = binder_available_for_proc_work_ilocked(thread);
        binder_inner_proc_unlock(proc);

        thread->looper |= BINDER_LOOPER_STATE_WAITING;

        trace_binder_wait_for_work(wait_for_proc_work,
                                   !!thread->transaction_stack,
                                   !binder_worklist_empty(proc, &thread->todo));
        if (wait_for_proc_work) {
                if (!(thread->looper & (BINDER_LOOPER_STATE_REGISTERED |
                                        BINDER_LOOPER_STATE_ENTERED))) {
                        binder_user_error("%d:%d ERROR: Thread waiting for process work before calling BC_REGISTER_LOOPER or BC_ENTER_LOOPER (state %x)\n",
                                proc->pid, thread->pid, thread->looper);
                        wait_event_interruptible(binder_user_error_wait,
                                                 binder_stop_on_user_error < 2);
                }
                binder_set_nice(proc->default_priority);
        }

        if (non_block) {
                if (!binder_has_work(thread, wait_for_proc_work))
                        ret = -EAGAIN;
        } else {
                ret = binder_wait_for_work(thread, wait_for_proc_work);
        }

        thread->looper &= ~BINDER_LOOPER_STATE_WAITING;

        if (ret)
                return ret;

        while (1) {
                uint32_t cmd;
                struct binder_transaction_data tr;
                struct binder_work *w = NULL;
                struct list_head *list = NULL;
                struct binder_transaction *t = NULL;
                struct binder_thread *t_from;

                binder_inner_proc_lock(proc);
                if (!binder_worklist_empty_ilocked(&thread->todo))
                        list = &thread->todo;
                else if (!binder_worklist_empty_ilocked(&proc->todo) &&
                           wait_for_proc_work)
                        list = &proc->todo;
                else {
                        binder_inner_proc_unlock(proc);

                        /* no data added */
                        if (ptr - buffer == 4 && !thread->looper_need_return)
                                goto retry;
                        break;
                }

                if (end - ptr < sizeof(tr) + 4) {
                        binder_inner_proc_unlock(proc);
                        break;
                }
                w = binder_dequeue_work_head_ilocked(list);
                if (binder_worklist_empty_ilocked(&thread->todo))
                        thread->process_todo = false;

                switch (w->type) {
                case BINDER_WORK_TRANSACTION: {
                        binder_inner_proc_unlock(proc);
                        t = container_of(w, struct binder_transaction, work);
                } break;
                case BINDER_WORK_RETURN_ERROR: {
                        struct binder_error *e = container_of(
                                        w, struct binder_error, work);

                        WARN_ON(e->cmd == BR_OK);
                        binder_inner_proc_unlock(proc);
                        if (put_user(e->cmd, (uint32_t __user *)ptr))
                                return -EFAULT;
                        e->cmd = BR_OK;
                        ptr += sizeof(uint32_t);

                        binder_stat_br(proc, thread, e->cmd);
                } break;
                case BINDER_WORK_TRANSACTION_COMPLETE: {
                        binder_inner_proc_unlock(proc);
                        cmd = BR_TRANSACTION_COMPLETE;
                        if (put_user(cmd, (uint32_t __user *)ptr))
                                return -EFAULT;
                        ptr += sizeof(uint32_t);

                        binder_stat_br(proc, thread, cmd);
                        binder_debug(BINDER_DEBUG_TRANSACTION_COMPLETE,
                                     "%d:%d BR_TRANSACTION_COMPLETE\n",
                                     proc->pid, thread->pid);
                        kfree(w);
                        binder_stats_deleted(BINDER_STAT_TRANSACTION_COMPLETE);
                } break;
                case BINDER_WORK_NODE: {
                        struct binder_node *node = container_of(w, struct binder_node, work);
                        int strong, weak;
                        binder_uintptr_t node_ptr = node->ptr;
                        binder_uintptr_t node_cookie = node->cookie;
                        int node_debug_id = node->debug_id;
                        int has_weak_ref;
                        int has_strong_ref;
                        void __user *orig_ptr = ptr;

                        BUG_ON(proc != node->proc);
                        strong = node->internal_strong_refs ||
                                        node->local_strong_refs;
                        weak = !hlist_empty(&node->refs) ||
                                        node->local_weak_refs ||
                                        node->tmp_refs || strong;
                        has_strong_ref = node->has_strong_ref;
                        has_weak_ref = node->has_weak_ref;

                        if (weak && !has_weak_ref) {
                                node->has_weak_ref = 1;
                                node->pending_weak_ref = 1;
                                node->local_weak_refs++;
                        }
                        if (strong && !has_strong_ref) {
                                node->has_strong_ref = 1;
                                node->pending_strong_ref = 1;
                                node->local_strong_refs++;
                        }
                        if (!strong && has_strong_ref)
                                node->has_strong_ref = 0;
                        if (!weak && has_weak_ref)
                                node->has_weak_ref = 0;
                        if (!weak && !strong) {
                                binder_debug(BINDER_DEBUG_INTERNAL_REFS,
                                             "%d:%d node %d u%016llx c%016llx deleted\n",
                                             proc->pid, thread->pid,
                                             node_debug_id,
                                             (u64)node_ptr,
                                             (u64)node_cookie);
                                rb_erase(&node->rb_node, &proc->nodes);
                                binder_inner_proc_unlock(proc);
                                binder_node_lock(node);
                                /*
                                 * Acquire the node lock before freeing the
                                 * node to serialize with other threads that
                                 * may have been holding the node lock while
                                 * decrementing this node (avoids race where
                                 * this thread frees while the other thread
                                 * is unlocking the node after the final
                                 * decrement)
                                 */
                                binder_node_unlock(node);
                                binder_free_node(node);
                        } else
                                binder_inner_proc_unlock(proc);

                        if (weak && !has_weak_ref)
                                ret = binder_put_node_cmd(
                                                proc, thread, &ptr, node_ptr,
                                                node_cookie, node_debug_id,
                                                BR_INCREFS, "BR_INCREFS");