#include "audit.h"
#include <linux/inotify.h>
#include <linux/namei.h>
#include <linux/mount.h>
#include <linux/kthread.h>

struct audit_tree;
struct audit_chunk;

struct audit_tree {
        atomic_t count;
        int goner;
        struct audit_chunk *root;
        struct list_head chunks;
        struct list_head rules;
        struct list_head list;
        struct list_head same_root;
        struct rcu_head head;
        char pathname[];
};

struct audit_chunk {
        struct list_head hash;
        struct inotify_watch watch;
        struct list_head trees;         /* with root here */
        int dead;
        int count;
        atomic_long_t refs;
        struct rcu_head head;
        struct node {
                struct list_head list;
                struct audit_tree *owner;
                unsigned index;         /* index; upper bit indicates 'will prune' */
        } owners[];
};

static LIST_HEAD(tree_list);
static LIST_HEAD(prune_list);

/*
 * One struct chunk is attached to each inode of interest.
 * We replace struct chunk on tagging/untagging.
 * Rules have pointer to struct audit_tree.
 * Rules have struct list_head rlist forming a list of rules over
 * the same tree.
 * References to struct chunk are collected at audit_inode{,_child}()
 * time and used in AUDIT_TREE rule matching.
 * These references are dropped at the same time we are calling
 * audit_free_names(), etc.
 *
 * Cyclic lists galore:
 * tree.chunks anchors chunk.owners[].list                      hash_lock
 * tree.rules anchors rule.rlist                                audit_filter_mutex
 * chunk.trees anchors tree.same_root                           hash_lock
 * chunk.hash is a hash with middle bits of watch.inode as
 * a hash function.                                             RCU, hash_lock
 *
 * tree is refcounted; one reference for "some rules on rules_list refer to
 * it", one for each chunk with pointer to it.
 *
 * chunk is refcounted by embedded inotify_watch + .refs (non-zero refcount
 * of watch contributes 1 to .refs).
 *
 * node.index allows to get from node.list to containing chunk.
 * MSB of that sucker is stolen to mark taggings that we might have to
 * revert - several operations have very unpleasant cleanup logics and
 * that makes a difference.  Some.
 */

static struct inotify_handle *rtree_ih;

static struct audit_tree *alloc_tree(const char *s)
{
        struct audit_tree *tree;

        tree = kmalloc(sizeof(struct audit_tree) + strlen(s) + 1, GFP_KERNEL);
        if (tree) {
                atomic_set(&tree->count, 1);
                tree->goner = 0;
                INIT_LIST_HEAD(&tree->chunks);
                INIT_LIST_HEAD(&tree->rules);
                INIT_LIST_HEAD(&tree->list);
                INIT_LIST_HEAD(&tree->same_root);
                tree->root = NULL;
                strcpy(tree->pathname, s);
        }
        return tree;
}

static inline void get_tree(struct audit_tree *tree)
{
        atomic_inc(&tree->count);
}

static void __put_tree(struct rcu_head *rcu)
{
        struct audit_tree *tree = container_of(rcu, struct audit_tree, head);
        kfree(tree);
}

static inline void put_tree(struct audit_tree *tree)
{
        if (atomic_dec_and_test(&tree->count))
                call_rcu(&tree->head, __put_tree);
}

/* to avoid bringing the entire thing in audit.h */
const char *audit_tree_path(struct audit_tree *tree)
{
        return tree->pathname;
}

static struct audit_chunk *alloc_chunk(int count)
{
        struct audit_chunk *chunk;
        size_t size;
        int i;

        size = offsetof(struct audit_chunk, owners) + count * sizeof(struct node);
        chunk = kzalloc(size, GFP_KERNEL);
        if (!chunk)
                return NULL;

        INIT_LIST_HEAD(&chunk->hash);
        INIT_LIST_HEAD(&chunk->trees);
        chunk->count = count;
        atomic_long_set(&chunk->refs, 1);
        for (i = 0; i < count; i++) {
                INIT_LIST_HEAD(&chunk->owners[i].list);
                chunk->owners[i].index = i;
        }
        inotify_init_watch(&chunk->watch);
        return chunk;
}

static void free_chunk(struct audit_chunk *chunk)
{
        int i;

        for (i = 0; i < chunk->count; i++) {
                if (chunk->owners[i].owner)
                        put_tree(chunk->owners[i].owner);
        }
        kfree(chunk);
}

void audit_put_chunk(struct audit_chunk *chunk)
{
        if (atomic_long_dec_and_test(&chunk->refs))
                free_chunk(chunk);
}

static void __put_chunk(struct rcu_head *rcu)
{
        struct audit_chunk *chunk = container_of(rcu, struct audit_chunk, head);
        audit_put_chunk(chunk);
}

enum {HASH_SIZE = 128};
static struct list_head chunk_hash_heads[HASH_SIZE];
static __cacheline_aligned_in_smp DEFINE_SPINLOCK(hash_lock);

static inline struct list_head *chunk_hash(const struct inode *inode)
{
        unsigned long n = (unsigned long)inode / L1_CACHE_BYTES;
        return chunk_hash_heads + n % HASH_SIZE;
}

/* hash_lock is held by caller */
static void insert_hash(struct audit_chunk *chunk)
{
        struct list_head *list = chunk_hash(chunk->watch.inode);
        list_add_rcu(&chunk->hash, list);
}

/* called under rcu_read_lock */
struct audit_chunk *audit_tree_lookup(const struct inode *inode)
{
        struct list_head *list = chunk_hash(inode);
        struct audit_chunk *p;

        list_for_each_entry_rcu(p, list, hash) {
                if (p->watch.inode == inode) {
                        atomic_long_inc(&p->refs);
                        return p;
                }
        }
        return NULL;
}

int audit_tree_match(struct audit_chunk *chunk, struct audit_tree *tree)
{
        int n;
        for (n = 0; n < chunk->count; n++)
                if (chunk->owners[n].owner == tree)
                        return 1;
        return 0;
}

/* tagging and untagging inodes with trees */

static struct audit_chunk *find_chunk(struct node *p)
{
        int index = p->index & ~(1U<<31);
        p -= index;
        return container_of(p, struct audit_chunk, owners[0]);
}

static void untag_chunk(struct node *p)
{
        struct audit_chunk *chunk = find_chunk(p);
        struct audit_chunk *new;
        struct audit_tree *owner;
        int size = chunk->count - 1;
        int i, j;

        if (!pin_inotify_watch(&chunk->watch)) {
                /*
                 * Filesystem is shutting down; all watches are getting
                 * evicted, just take it off the node list for this
                 * tree and let the eviction logics take care of the
                 * rest.
                 */
                owner = p->owner;
                if (owner->root == chunk) {
                        list_del_init(&owner->same_root);
                        owner->root = NULL;
                }
                list_del_init(&p->list);
                p->owner = NULL;
                put_tree(owner);
                return;
        }

        spin_unlock(&hash_lock);

        /*
         * pin_inotify_watch() succeeded, so the watch won't go away
         * from under us.
         */
        mutex_lock(&chunk->watch.inode->inotify_mutex);
        if (chunk->dead) {
                mutex_unlock(&chunk->watch.inode->inotify_mutex);
                goto out;
        }

        owner = p->owner;

        if (!size) {
                chunk->dead = 1;
                spin_lock(&hash_lock);
                list_del_init(&chunk->trees);
                if (owner->root == chunk)
                        owner->root = NULL;
                list_del_init(&p->list);
                list_del_rcu(&chunk->hash);
                spin_unlock(&hash_lock);
                inotify_evict_watch(&chunk->watch);
                mutex_unlock(&chunk->watch.inode->inotify_mutex);
                put_inotify_watch(&chunk->watch);
                goto out;
        }

        new = alloc_chunk(size);
        if (!new)
                goto Fallback;
        if (inotify_clone_watch(&chunk->watch, &new->watch) < 0) {
                free_chunk(new);
                goto Fallback;
        }

        chunk->dead = 1;
        spin_lock(&hash_lock);
        list_replace_init(&chunk->trees, &new->trees);
        if (owner->root == chunk) {
                list_del_init(&owner->same_root);
                owner->root = NULL;
        }

        for (i = j = 0; i < size; i++, j++) {
                struct audit_tree *s;
                if (&chunk->owners[j] == p) {
                        list_del_init(&p->list);
                        i--;
                        continue;
                }
                s = chunk->owners[j].owner;
                new->owners[i].owner = s;
                new->owners[i].index = chunk->owners[j].index - j + i;
                if (!s) /* result of earlier fallback */
                        continue;
                get_tree(s);
                list_replace_init(&chunk->owners[i].list, &new->owners[j].list);
        }

        list_replace_rcu(&chunk->hash, &new->hash);
        list_for_each_entry(owner, &new->trees, same_root)
                owner->root = new;
        spin_unlock(&hash_lock);
        inotify_evict_watch(&chunk->watch);
        mutex_unlock(&chunk->watch.inode->inotify_mutex);
        put_inotify_watch(&chunk->watch);
        goto out;

Fallback:
        // do the best we can
        spin_lock(&hash_lock);
        if (owner->root == chunk) {
                list_del_init(&owner->same_root);
                owner->root = NULL;
        }
        list_del_init(&p->list);
        p->owner = NULL;
        put_tree(owner);
        spin_unlock(&hash_lock);
        mutex_unlock(&chunk->watch.inode->inotify_mutex);
out:
        unpin_inotify_watch(&chunk->watch);
        spin_lock(&hash_lock);
}

static int create_chunk(struct inode *inode, struct audit_tree *tree)
{
        struct audit_chunk *chunk = alloc_chunk(1);
        if (!chunk)
                return -ENOMEM;

        if (inotify_add_watch(rtree_ih, &chunk->watch, inode, IN_IGNORED | IN_DELETE_SELF) < 0) {
                free_chunk(chunk);
                return -ENOSPC;
        }

        mutex_lock(&inode->inotify_mutex);
        spin_lock(&hash_lock);
        if (tree->goner) {
                spin_unlock(&hash_lock);
                chunk->dead = 1;
                inotify_evict_watch(&chunk->watch);
                mutex_unlock(&inode->inotify_mutex);
                put_inotify_watch(&chunk->watch);
                return 0;
        }
        chunk->owners[0].index = (1U << 31);
        chunk->owners[0].owner = tree;
        get_tree(tree);
        list_add(&chunk->owners[0].list, &tree->chunks);
        if (!tree->root) {
                tree->root = chunk;
                list_add(&tree->same_root, &chunk->trees);
        }
        insert_hash(chunk);
        spin_unlock(&hash_lock);
        mutex_unlock(&inode->inotify_mutex);
        return 0;
}

/* the first tagged inode becomes root of tree */
static int tag_chunk(struct inode *inode, struct audit_tree *tree)
{
        struct inotify_watch *watch;
        struct audit_tree *owner;
        struct audit_chunk *chunk, *old;
        struct node *p;
        int n;

        if (inotify_find_watch(rtree_ih, inode, &watch) < 0)
                return create_chunk(inode, tree);

        old = container_of(watch, struct audit_chunk, watch);

        /* are we already there? */
        spin_lock(&hash_lock);
        for (n = 0; n < old->count; n++) {
                if (old->owners[n].owner == tree) {
                        spin_unlock(&hash_lock);
                        put_inotify_watch(watch);
                        return 0;
                }
        }
        spin_unlock(&hash_lock);

        chunk = alloc_chunk(old->count + 1);
        if (!chunk)
                return -ENOMEM;

        mutex_lock(&inode->inotify_mutex);
        if (inotify_clone_watch(&old->watch, &chunk->watch) < 0) {
                mutex_unlock(&inode->inotify_mutex);
                put_inotify_watch(&old->watch);
                free_chunk(chunk);
                return -ENOSPC;
        }
        spin_lock(&hash_lock);
        if (tree->goner) {
                spin_unlock(&hash_lock);
                chunk->dead = 1;
                inotify_evict_watch(&chunk->watch);
                mutex_unlock(&inode->inotify_mutex);
                put_inotify_watch(&old->watch);
                put_inotify_watch(&chunk->watch);
                return 0;
        }
        list_replace_init(&old->trees, &chunk->trees);
        for (n = 0, p = chunk->owners; n < old->count; n++, p++) {
                struct audit_tree *s = old->owners[n].owner;
                p->owner = s;
                p->index = old->owners[n].index;
                if (!s) /* result of fallback in untag */
                        continue;
                get_tree(s);
                list_replace_init(&old->owners[n].list, &p->list);
        }
        p->index = (chunk->count - 1) | (1U<<31);
        p->owner = tree;
        get_tree(tree);
        list_add(&p->list, &tree->chunks);
        list_replace_rcu(&old->hash, &chunk->hash);
        list_for_each_entry(owner, &chunk->trees, same_root)
                owner->root = chunk;
        old->dead = 1;
        if (!tree->root) {
                tree->root = chunk;
                list_add(&tree->same_root, &chunk->trees);
        }
        spin_unlock(&hash_lock);
        inotify_evict_watch(&old->watch);
        mutex_unlock(&inode->inotify_mutex);
        put_inotify_watch(&old->watch);
        return 0;
}

static void kill_rules(struct audit_tree *tree)
{
        struct audit_krule *rule, *next;
        struct audit_entry *entry;
        struct audit_buffer *ab;

        list_for_each_entry_safe(rule, next, &tree->rules, rlist) {
                entry = container_of(rule, struct audit_entry, rule);

                list_del_init(&rule->rlist);
                if (rule->tree) {
                        /* not a half-baked one */
                        ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE);
                        audit_log_format(ab, "op=");
                        audit_log_string(ab, "remove rule");
                        audit_log_format(ab, " dir=");
                        audit_log_untrustedstring(ab, rule->tree->pathname);
                        audit_log_key(ab, rule->filterkey);
                        audit_log_format(ab, " list=%d res=1", rule->listnr);
                        audit_log_end(ab);
                        rule->tree = NULL;
                        list_del_rcu(&entry->list);
                        list_del(&entry->rule.list);
                        call_rcu(&entry->rcu, audit_free_rule_rcu);
                }
        }
}

/*
 * finish killing struct audit_tree
 */
static void prune_one(struct audit_tree *victim)
{
        spin_lock(&hash_lock);
        while (!list_empty(&victim->chunks)) {
                struct node *p;

                p = list_entry(victim->chunks.next, struct node, list);

                untag_chunk(p);
        }
        spin_unlock(&hash_lock);
        put_tree(victim);
}

/* trim the uncommitted chunks from tree */

static void trim_marked(struct audit_tree *tree)
{
        struct list_head *p, *q;
        spin_lock(&hash_lock);
        if (tree->goner) {
                spin_unlock(&hash_lock);
                return;
        }
        /* reorder */
        for (p = tree->chunks.next; p != &tree->chunks; p = q) {
                struct node *node = list_entry(p, struct node, list);
                q = p->next;
                if (node->index & (1U<<31)) {
                        list_del_init(p);
                        list_add(p, &tree->chunks);
                }
        }

        while (!list_empty(&tree->chunks)) {
                struct node *node;

                node = list_entry(tree->chunks.next, struct node, list);

                /* have we run out of marked? */
                if (!(node->index & (1U<<31)))
                        break;

                untag_chunk(node);
        }
        if (!tree->root && !tree->goner) {
                tree->goner = 1;
                spin_unlock(&hash_lock);
                mutex_lock(&audit_filter_mutex);
                kill_rules(tree);
                list_del_init(&tree->list);
                mutex_unlock(&audit_filter_mutex);
                prune_one(tree);
        } else {
                spin_unlock(&hash_lock);
        }
}

static void audit_schedule_prune(void);

/* called with audit_filter_mutex */
int audit_remove_tree_rule(struct audit_krule *rule)
{
        struct audit_tree *tree;
        tree = rule->tree;
        if (tree) {
                spin_lock(&hash_lock);
                list_del_init(&rule->rlist);
                if (list_empty(&tree->rules) && !tree->goner) {
                        tree->root = NULL;
                        list_del_init(&tree->same_root);
                        tree->goner = 1;
                        list_move(&tree->list, &prune_list);
                        rule->tree = NULL;
                        spin_unlock(&hash_lock);
                        audit_schedule_prune();
                        return 1;
                }
                rule->tree = NULL;
                spin_unlock(&hash_lock);
                return 1;
        }
        return 0;
}

void audit_trim_trees(void)
{
        struct list_head cursor;

        mutex_lock(&audit_filter_mutex);
        list_add(&cursor, &tree_list);
        while (cursor.next != &tree_list) {
                struct audit_tree *tree;
                struct path path;
                struct vfsmount *root_mnt;
                struct node *node;
                struct list_head list;
                int err;

                tree = container_of(cursor.next, struct audit_tree, list);
                get_tree(tree);
                list_del(&cursor);
                list_add(&cursor, &tree->list);
                mutex_unlock(&audit_filter_mutex);

                err = kern_path(tree->pathname, 0, &path);
                if (err)
                        goto skip_it;

                root_mnt = collect_mounts(&path);
                path_put(&path);
                if (!root_mnt)
                        goto skip_it;

                list_add_tail(&list, &root_mnt->mnt_list);
                spin_lock(&hash_lock);
                list_for_each_entry(node, &tree->chunks, list) {
                        struct audit_chunk *chunk = find_chunk(node);
                        struct inode *inode = chunk->watch.inode;
                        struct vfsmount *mnt;
                        node->index |= 1U<<31;
                        list_for_each_entry(mnt, &list, mnt_list) {
                                if (mnt->mnt_root->d_inode == inode) {
                                        node->index &= ~(1U<<31);
                                        break;
                                }
                        }
                }
                spin_unlock(&hash_lock);
                trim_marked(tree);
                put_tree(tree);
                list_del_init(&list);
                drop_collected_mounts(root_mnt);
skip_it:
                mutex_lock(&audit_filter_mutex);
        }
        list_del(&cursor);
        mutex_unlock(&audit_filter_mutex);
}

static int is_under(struct vfsmount *mnt, struct dentry *dentry,
                    struct path *path)
{
        if (mnt != path->mnt) {
                for (;;) {
                        if (mnt->mnt_parent == mnt)
                                return 0;
                        if (mnt->mnt_parent == path->mnt)
                                        break;
                        mnt = mnt->mnt_parent;
                }
                dentry = mnt->mnt_mountpoint;
        }
        return is_subdir(dentry, path->dentry);
}

int audit_make_tree(struct audit_krule *rule, char *pathname, u32 op)
{

        if (pathname[0] != '/' ||
            rule->listnr != AUDIT_FILTER_EXIT ||
            op != Audit_equal ||
            rule->inode_f || rule->watch || rule->tree)
                return -EINVAL;
        rule->tree = alloc_tree(pathname);
        if (!rule->tree)
                return -ENOMEM;
        return 0;
}

void audit_put_tree(struct audit_tree *tree)
{
        put_tree(tree);
}

/* called with audit_filter_mutex */
int audit_add_tree_rule(struct audit_krule *rule)
{
        struct audit_tree *seed = rule->tree, *tree;
        struct path path;
        struct vfsmount *mnt, *p;
        struct list_head list;
        int err;

        list_for_each_entry(tree, &tree_list, list) {
                if (!strcmp(seed->pathname, tree->pathname)) {
                        put_tree(seed);
                        rule->tree = tree;
                        list_add(&rule->rlist, &tree->rules);
                        return 0;
                }
        }
        tree = seed;
        list_add(&tree->list, &tree_list);
        list_add(&rule->rlist, &tree->rules);
        /* do not set rule->tree yet */
        mutex_unlock(&audit_filter_mutex);

        err = kern_path(tree->pathname, 0, &path);
        if (err)
                goto Err;
        mnt = collect_mounts(&path);
        path_put(&path);
        if (!mnt) {
                err = -ENOMEM;
                goto Err;
        }
        list_add_tail(&list, &mnt->mnt_list);

        get_tree(tree);
        list_for_each_entry(p, &list, mnt_list) {
                err = tag_chunk(p->mnt_root->d_inode, tree);
                if (err)
                        break;
        }

        list_del(&list);
        drop_collected_mounts(mnt);

        if (!err) {
                struct node *node;
                spin_lock(&hash_lock);
                list_for_each_entry(node, &tree->chunks, list)
                        node->index &= ~(1U<<31);
                spin_unlock(&hash_lock);
        } else {
                trim_marked(tree);
                goto Err;
        }

        mutex_lock(&audit_filter_mutex);
        if (list_empty(&rule->rlist)) {
                put_tree(tree);
                return -ENOENT;
        }
        rule->tree = tree;
        put_tree(tree);

        return 0;
Err:
        mutex_lock(&audit_filter_mutex);
        list_del_init(&tree->list);
        list_del_init(&tree->rules);
        put_tree(tree);
        return err;
}

int audit_tag_tree(char *old, char *new)
{
        struct list_head cursor, barrier;
        int failed = 0;
        struct path path;
        struct vfsmount *tagged;
        struct list_head list;
        struct vfsmount *mnt;
        struct dentry *dentry;
        int err;

        err = kern_path(new, 0, &path);
        if (err)
                return err;
        tagged = collect_mounts(&path);
        path_put(&path);
        if (!tagged)
                return -ENOMEM;

        err = kern_path(old, 0, &path);
        if (err) {
                drop_collected_mounts(tagged);
                return err;
        }
        mnt = mntget(path.mnt);
        dentry = dget(path.dentry);
        path_put(&path);

        list_add_tail(&list, &tagged->mnt_list);

        mutex_lock(&audit_filter_mutex);
        list_add(&barrier, &tree_list);
        list_add(&cursor, &barrier);

        while (cursor.next != &tree_list) {
                struct audit_tree *tree;
                struct vfsmount *p;

                tree = container_of(cursor.next, struct audit_tree, list);
                get_tree(tree);
                list_del(&cursor);
                list_add(&cursor, &tree->list);
                mutex_unlock(&audit_filter_mutex);

                err = kern_path(tree->pathname, 0, &path);
                if (err) {
                        put_tree(tree);
                        mutex_lock(&audit_filter_mutex);
                        continue;
                }

                spin_lock(&vfsmount_lock);
                if (!is_under(mnt, dentry, &path)) {
                        spin_unlock(&vfsmount_lock);
                        path_put(&path);
                        put_tree(tree);
                        mutex_lock(&audit_filter_mutex);
                        continue;
                }
                spin_unlock(&vfsmount_lock);
                path_put(&path);

                list_for_each_entry(p, &list, mnt_list) {
                        failed = tag_chunk(p->mnt_root->d_inode, tree);
                        if (failed)
                                break;
                }

                if (failed) {
                        put_tree(tree);
                        mutex_lock(&audit_filter_mutex);
                        break;
                }

                mutex_lock(&audit_filter_mutex);
                spin_lock(&hash_lock);
                if (!tree->goner) {
                        list_del(&tree->list);
                        list_add(&tree->list, &tree_list);
                }
                spin_unlock(&hash_lock);
                put_tree(tree);
        }

        while (barrier.prev != &tree_list) {
                struct audit_tree *tree;

                tree = container_of(barrier.prev, struct audit_tree, list);
                get_tree(tree);
                list_del(&tree->list);
                list_add(&tree->list, &barrier);
                mutex_unlock(&audit_filter_mutex);

                if (!failed) {
                        struct node *node;
                        spin_lock(&hash_lock);
                        list_for_each_entry(node, &tree->chunks, list)
                                node->index &= ~(1U<<31);
                        spin_unlock(&hash_lock);
                } else {
                        trim_marked(tree);
                }

                put_tree(tree);
                mutex_lock(&audit_filter_mutex);
        }
        list_del(&barrier);
        list_del(&cursor);
        list_del(&list);
        mutex_unlock(&audit_filter_mutex);
        dput(dentry);
        mntput(mnt);
        drop_collected_mounts(tagged);
        return failed;
}

/*
 * That gets run when evict_chunk() ends up needing to kill audit_tree.
 * Runs from a separate thread.
 */
static int prune_tree_thread(void *unused)
{
        mutex_lock(&audit_cmd_mutex);
        mutex_lock(&audit_filter_mutex);

        while (!list_empty(&prune_list)) {
                struct audit_tree *victim;

                victim = list_entry(prune_list.next, struct audit_tree, list);
                list_del_init(&victim->list);

                mutex_unlock(&audit_filter_mutex);

                prune_one(victim);

                mutex_lock(&audit_filter_mutex);
        }

        mutex_unlock(&audit_filter_mutex);
        mutex_unlock(&audit_cmd_mutex);
        return 0;
}

static void audit_schedule_prune(void)
{
        kthread_run(prune_tree_thread, NULL, "audit_prune_tree");
}

/*
 * ... and that one is done if evict_chunk() decides to delay until the end
 * of syscall.  Runs synchronously.
 */
void audit_kill_trees(struct list_head *list)
{
        mutex_lock(&audit_cmd_mutex);
        mutex_lock(&audit_filter_mutex);

        while (!list_empty(list)) {
                struct audit_tree *victim;

                victim = list_entry(list->next, struct audit_tree, list);
                kill_rules(victim);
                list_del_init(&victim->list);

                mutex_unlock(&audit_filter_mutex);

                prune_one(victim);

                mutex_lock(&audit_filter_mutex);
        }

        mutex_unlock(&audit_filter_mutex);
        mutex_unlock(&audit_cmd_mutex);
}

/*
 *  Here comes the stuff asynchronous to auditctl operations
 */

/* inode->inotify_mutex is locked */
static void evict_chunk(struct audit_chunk *chunk)
{
        struct audit_tree *owner;
        struct list_head *postponed = audit_killed_trees();
        int need_prune = 0;
        int n;

        if (chunk->dead)
                return;

        chunk->dead = 1;
        mutex_lock(&audit_filter_mutex);
        spin_lock(&hash_lock);
        while (!list_empty(&chunk->trees)) {
                owner = list_entry(chunk->trees.next,
                                   struct audit_tree, same_root);
                owner->goner = 1;
                owner->root = NULL;
                list_del_init(&owner->same_root);
                spin_unlock(&hash_lock);
                if (!postponed) {
                        kill_rules(owner);
                        list_move(&owner->list, &prune_list);
                        need_prune = 1;
                } else {
                        list_move(&owner->list, postponed);
                }
                spin_lock(&hash_lock);
        }
        list_del_rcu(&chunk->hash);
        for (n = 0; n < chunk->count; n++)
                list_del_init(&chunk->owners[n].list);
        spin_unlock(&hash_lock);
        if (need_prune)
                audit_schedule_prune();
        mutex_unlock(&audit_filter_mutex);
}

static void handle_event(struct inotify_watch *watch, u32 wd, u32 mask,
                         u32 cookie, const char *dname, struct inode *inode)
{
        struct audit_chunk *chunk = container_of(watch, struct audit_chunk, watch);

        if (mask & IN_IGNORED) {
                evict_chunk(chunk);
                put_inotify_watch(watch);
        }
}

static void destroy_watch(struct inotify_watch *watch)
{
        struct audit_chunk *chunk = container_of(watch, struct audit_chunk, watch);
        call_rcu(&chunk->head, __put_chunk);
}

static const struct inotify_operations rtree_inotify_ops = {
        .handle_event   = handle_event,
        .destroy_watch  = destroy_watch,
};

static int __init audit_tree_init(void)
{
        int i;

        rtree_ih = inotify_init(&rtree_inotify_ops);
        if (IS_ERR(rtree_ih))
                audit_panic("cannot initialize inotify handle for rectree watches");

        for (i = 0; i < HASH_SIZE; i++)
                INIT_LIST_HEAD(&chunk_hash_heads[i]);

        return 0;
}
__initcall(audit_tree_init);