LXR linux/kernel/cgroup/cgroup-internal.h

   1/* SPDX-License-Identifier: GPL-2.0 */
   2#ifndef __CGROUP_INTERNAL_H
   3#define __CGROUP_INTERNAL_H
   4
   5#include <linux/cgroup.h>
   6#include <linux/kernfs.h>
   7#include <linux/workqueue.h>
   8#include <linux/list.h>
   9#include <linux/refcount.h>
  10
  11#define TRACE_CGROUP_PATH_LEN 1024
  12extern spinlock_t trace_cgroup_path_lock;
  13extern char trace_cgroup_path[TRACE_CGROUP_PATH_LEN];
  14
  15/*
  16 * cgroup_path() takes a spin lock. It is good practice not to take
  17 * spin locks within trace point handlers, as they are mostly hidden
  18 * from normal view. As cgroup_path() can take the kernfs_rename_lock
  19 * spin lock, it is best to not call that function from the trace event
  20 * handler.
  21 *
  22 * Note: trace_cgroup_##type##_enabled() is a static branch that will only
  23 *       be set when the trace event is enabled.
  24 */
  25#define TRACE_CGROUP_PATH(type, cgrp, ...)                              \
  26        do {                                                            \
  27                if (trace_cgroup_##type##_enabled()) {                  \
  28                        spin_lock(&trace_cgroup_path_lock);             \
  29                        cgroup_path(cgrp, trace_cgroup_path,            \
  30                                    TRACE_CGROUP_PATH_LEN);             \
  31                        trace_cgroup_##type(cgrp, trace_cgroup_path,    \
  32                                            ##__VA_ARGS__);             \
  33                        spin_unlock(&trace_cgroup_path_lock);           \
  34                }                                                       \
  35        } while (0)
  36
  37/*
  38 * A cgroup can be associated with multiple css_sets as different tasks may
  39 * belong to different cgroups on different hierarchies.  In the other
  40 * direction, a css_set is naturally associated with multiple cgroups.
  41 * This M:N relationship is represented by the following link structure
  42 * which exists for each association and allows traversing the associations
  43 * from both sides.
  44 */
  45struct cgrp_cset_link {
  46        /* the cgroup and css_set this link associates */
  47        struct cgroup           *cgrp;
  48        struct css_set          *cset;
  49
  50        /* list of cgrp_cset_links anchored at cgrp->cset_links */
  51        struct list_head        cset_link;
  52
  53        /* list of cgrp_cset_links anchored at css_set->cgrp_links */
  54        struct list_head        cgrp_link;
  55};
  56
  57/* used to track tasks and csets during migration */
  58struct cgroup_taskset {
  59        /* the src and dst cset list running through cset->mg_node */
  60        struct list_head        src_csets;
  61        struct list_head        dst_csets;
  62
  63        /* the number of tasks in the set */
  64        int                     nr_tasks;
  65
  66        /* the subsys currently being processed */
  67        int                     ssid;
  68
  69        /*
  70         * Fields for cgroup_taskset_*() iteration.
  71         *
  72         * Before migration is committed, the target migration tasks are on
  73         * ->mg_tasks of the csets on ->src_csets.  After, on ->mg_tasks of
  74         * the csets on ->dst_csets.  ->csets point to either ->src_csets
  75         * or ->dst_csets depending on whether migration is committed.
  76         *
  77         * ->cur_csets and ->cur_task point to the current task position
  78         * during iteration.
  79         */
  80        struct list_head        *csets;
  81        struct css_set          *cur_cset;
  82        struct task_struct      *cur_task;
  83};
  84
  85/* migration context also tracks preloading */
  86struct cgroup_mgctx {
  87        /*
  88         * Preloaded source and destination csets.  Used to guarantee
  89         * atomic success or failure on actual migration.
  90         */
  91        struct list_head        preloaded_src_csets;
  92        struct list_head        preloaded_dst_csets;
  93
  94        /* tasks and csets to migrate */
  95        struct cgroup_taskset   tset;
  96
  97        /* subsystems affected by migration */
  98        u16                     ss_mask;
  99};
 100
 101#define CGROUP_TASKSET_INIT(tset)                                               \
 102{                                                                               \
 103        .src_csets              = LIST_HEAD_INIT(tset.src_csets),               \
 104        .dst_csets              = LIST_HEAD_INIT(tset.dst_csets),               \
 105        .csets                  = &tset.src_csets,                              \
 106}
 107
 108#define CGROUP_MGCTX_INIT(name)                                                 \
 109{                                                                               \
 110        LIST_HEAD_INIT(name.preloaded_src_csets),                               \
 111        LIST_HEAD_INIT(name.preloaded_dst_csets),                               \
 112        CGROUP_TASKSET_INIT(name.tset),                                         \
 113}
 114
 115#define DEFINE_CGROUP_MGCTX(name)                                               \
 116        struct cgroup_mgctx name = CGROUP_MGCTX_INIT(name)
 117
 118struct cgroup_sb_opts {
 119        u16 subsys_mask;
 120        unsigned int flags;
 121        char *release_agent;
 122        bool cpuset_clone_children;
 123        char *name;
 124        /* User explicitly requested empty subsystem */
 125        bool none;
 126};
 127
 128extern struct mutex cgroup_mutex;
 129extern spinlock_t css_set_lock;
 130extern struct cgroup_subsys *cgroup_subsys[];
 131extern struct list_head cgroup_roots;
 132extern struct file_system_type cgroup_fs_type;
 133
 134/* iterate across the hierarchies */
 135#define for_each_root(root)                                             \
 136        list_for_each_entry((root), &cgroup_roots, root_list)
 137
 138/**
 139 * for_each_subsys - iterate all enabled cgroup subsystems
 140 * @ss: the iteration cursor
 141 * @ssid: the index of @ss, CGROUP_SUBSYS_COUNT after reaching the end
 142 */
 143#define for_each_subsys(ss, ssid)                                       \
 144        for ((ssid) = 0; (ssid) < CGROUP_SUBSYS_COUNT &&                \
 145             (((ss) = cgroup_subsys[ssid]) || true); (ssid)++)
 146
 147static inline bool cgroup_is_dead(const struct cgroup *cgrp)
 148{
 149        return !(cgrp->self.flags & CSS_ONLINE);
 150}
 151
 152static inline bool notify_on_release(const struct cgroup *cgrp)
 153{
 154        return test_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags);
 155}
 156
 157void put_css_set_locked(struct css_set *cset);
 158
 159static inline void put_css_set(struct css_set *cset)
 160{
 161        unsigned long flags;
 162
 163        /*
 164         * Ensure that the refcount doesn't hit zero while any readers
 165         * can see it. Similar to atomic_dec_and_lock(), but for an
 166         * rwlock
 167         */
 168        if (refcount_dec_not_one(&cset->refcount))
 169                return;
 170
 171        spin_lock_irqsave(&css_set_lock, flags);
 172        put_css_set_locked(cset);
 173        spin_unlock_irqrestore(&css_set_lock, flags);
 174}
 175
 176/*
 177 * refcounted get/put for css_set objects
 178 */
 179static inline void get_css_set(struct css_set *cset)
 180{
 181        refcount_inc(&cset->refcount);
 182}
 183
 184bool cgroup_ssid_enabled(int ssid);
 185bool cgroup_on_dfl(const struct cgroup *cgrp);
 186bool cgroup_is_thread_root(struct cgroup *cgrp);
 187bool cgroup_is_threaded(struct cgroup *cgrp);
 188
 189struct cgroup_root *cgroup_root_from_kf(struct kernfs_root *kf_root);
 190struct cgroup *task_cgroup_from_root(struct task_struct *task,
 191                                     struct cgroup_root *root);
 192struct cgroup *cgroup_kn_lock_live(struct kernfs_node *kn, bool drain_offline);
 193void cgroup_kn_unlock(struct kernfs_node *kn);
 194int cgroup_path_ns_locked(struct cgroup *cgrp, char *buf, size_t buflen,
 195                          struct cgroup_namespace *ns);
 196
 197void cgroup_free_root(struct cgroup_root *root);
 198void init_cgroup_root(struct cgroup_root *root, struct cgroup_sb_opts *opts);
 199int cgroup_setup_root(struct cgroup_root *root, u16 ss_mask, int ref_flags);
 200int rebind_subsystems(struct cgroup_root *dst_root, u16 ss_mask);
 201struct dentry *cgroup_do_mount(struct file_system_type *fs_type, int flags,
 202                               struct cgroup_root *root, unsigned long magic,
 203                               struct cgroup_namespace *ns);
 204
 205int cgroup_migrate_vet_dst(struct cgroup *dst_cgrp);
 206void cgroup_migrate_finish(struct cgroup_mgctx *mgctx);
 207void cgroup_migrate_add_src(struct css_set *src_cset, struct cgroup *dst_cgrp,
 208                            struct cgroup_mgctx *mgctx);
 209int cgroup_migrate_prepare_dst(struct cgroup_mgctx *mgctx);
 210int cgroup_migrate(struct task_struct *leader, bool threadgroup,
 211                   struct cgroup_mgctx *mgctx);
 212
 213int cgroup_attach_task(struct cgroup *dst_cgrp, struct task_struct *leader,
 214                       bool threadgroup);
 215struct task_struct *cgroup_procs_write_start(char *buf, bool threadgroup)
 216        __acquires(&cgroup_threadgroup_rwsem);
 217void cgroup_procs_write_finish(struct task_struct *task)
 218        __releases(&cgroup_threadgroup_rwsem);
 219
 220void cgroup_lock_and_drain_offline(struct cgroup *cgrp);
 221
 222int cgroup_mkdir(struct kernfs_node *parent_kn, const char *name, umode_t mode);
 223int cgroup_rmdir(struct kernfs_node *kn);
 224int cgroup_show_path(struct seq_file *sf, struct kernfs_node *kf_node,
 225                     struct kernfs_root *kf_root);
 226
 227int cgroup_task_count(const struct cgroup *cgrp);
 228
 229/*
 230 * rstat.c
 231 */
 232int cgroup_rstat_init(struct cgroup *cgrp);
 233void cgroup_rstat_exit(struct cgroup *cgrp);
 234void cgroup_rstat_boot(void);
 235void cgroup_base_stat_cputime_show(struct seq_file *seq);
 236
 237/*
 238 * namespace.c
 239 */
 240extern const struct proc_ns_operations cgroupns_operations;
 241
 242/*
 243 * cgroup-v1.c
 244 */
 245extern struct cftype cgroup1_base_files[];
 246extern struct kernfs_syscall_ops cgroup1_kf_syscall_ops;
 247
 248int proc_cgroupstats_show(struct seq_file *m, void *v);
 249bool cgroup1_ssid_disabled(int ssid);
 250void cgroup1_pidlist_destroy_all(struct cgroup *cgrp);
 251void cgroup1_release_agent(struct work_struct *work);
 252void cgroup1_check_for_release(struct cgroup *cgrp);
 253struct dentry *cgroup1_mount(struct file_system_type *fs_type, int flags,
 254                             void *data, unsigned long magic,
 255                             struct cgroup_namespace *ns);
 256
 257#endif /* __CGROUP_INTERNAL_H */
 258