fsnotify: Detach mark from object list when last reference is dropped

[sfrench/cifs-2.6.git] / kernel / audit_tree.c

diff --git a/kernel/audit_tree.c b/kernel/audit_tree.c
index c3b5fcb8eca4f34ce560cd58d5e6d0d6169362d9..2fa8d61b6fd2166e55de50c6ffa50f2868a3d6b9 100644 (file)
--- a/kernel/audit_tree.c
+++ b/kernel/audit_tree.c
@@ -172,27 +172,18 @@ static unsigned long inode_to_key(const struct inode *inode)
 /*
  * Function to return search key in our hash from chunk. Key 0 is special and
  * should never be present in the hash.
- *
- * Must be called with chunk->mark.lock held to protect from connector
- * becoming NULL.
  */
-static unsigned long __chunk_to_key(struct audit_chunk *chunk)
+static unsigned long chunk_to_key(struct audit_chunk *chunk)
 {
-       if (!chunk->mark.connector)
+       /*
+        * We have a reference to the mark so it should be attached to a
+        * connector.
+        */
+       if (WARN_ON_ONCE(!chunk->mark.connector))
                return 0;
        return (unsigned long)chunk->mark.connector->inode;
 }
 
-static unsigned long chunk_to_key(struct audit_chunk *chunk)
-{
-       unsigned long key;
-
-       spin_lock(&chunk->mark.lock);
-       key = __chunk_to_key(chunk);
-       spin_unlock(&chunk->mark.lock);
-       return key;
-}
-
 static inline struct list_head *chunk_hash(unsigned long key)
 {
        unsigned long n = key / L1_CACHE_BYTES;
@@ -202,7 +193,7 @@ static inline struct list_head *chunk_hash(unsigned long key)
 /* hash_lock & entry->lock is held by caller */
 static void insert_hash(struct audit_chunk *chunk)
 {
-       unsigned long key = __chunk_to_key(chunk);
+       unsigned long key = chunk_to_key(chunk);
        struct list_head *list;
 
        if (!(chunk->mark.flags & FSNOTIFY_MARK_FLAG_ATTACHED))
@@ -263,6 +254,10 @@ static void untag_chunk(struct node *p)
 
        mutex_lock(&entry->group->mark_mutex);
        spin_lock(&entry->lock);
+       /*
+        * mark_mutex protects mark from getting detached and thus also from
+        * mark->connector->inode getting NULL.
+        */
        if (chunk->dead || !(entry->flags & FSNOTIFY_MARK_FLAG_ATTACHED)) {
                spin_unlock(&entry->lock);
                mutex_unlock(&entry->group->mark_mutex);
@@ -423,6 +418,10 @@ static int tag_chunk(struct inode *inode, struct audit_tree *tree)
 
        mutex_lock(&old_entry->group->mark_mutex);
        spin_lock(&old_entry->lock);
+       /*
+        * mark_mutex protects mark from getting detached and thus also from
+        * mark->connector->inode getting NULL.
+        */
        if (!(old_entry->flags & FSNOTIFY_MARK_FLAG_ATTACHED)) {
                /* old_entry is being shot, lets just lie */
                spin_unlock(&old_entry->lock);