audit_tree: Remove mark->lock locking

Currently, audit_tree code uses mark->lock to protect against detaching
of mark from an inode. In most places it however also uses
mark->group->mark_mutex (as we need to atomically replace attached
marks) and this provides protection against mark detaching as well. So
just remove protection with mark->lock from audit tree code and replace
it with mark->group->mark_mutex protection in all the places. It
simplifies the code and gets rid of some ugly catches like calling
fsnotify_add_mark_locked() with mark->lock held (which cannot sleep only
because we hold a reference to another mark attached to the same inode).

Reviewed-by: Richard Guy Briggs <rgb@redhat.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Paul Moore <paul@paul-moore.com>

diff --git a/kernel/audit_tree.c b/kernel/audit_tree.c
index ea43181cde4a2d7efe7747ac5b9e0346ddbf5d3f..1b55b1026a36a1d5226525fefad42d5ea57f7391 100644 (file)
--- a/kernel/audit_tree.c
+++ b/kernel/audit_tree.c
@@ -193,7 +193,7 @@ static inline struct list_head *chunk_hash(unsigned long key)
        return chunk_hash_heads + n % HASH_SIZE;
 }
 
-/* hash_lock & entry->lock is held by caller */
+/* hash_lock & entry->group->mark_mutex is held by caller */
 static void insert_hash(struct audit_chunk *chunk)
 {
        unsigned long key = chunk_to_key(chunk);
@@ -256,13 +256,11 @@ static void untag_chunk(struct node *p)
                new = alloc_chunk(size);
 
        mutex_lock(&entry->group->mark_mutex);
-       spin_lock(&entry->lock);
        /*
         * mark_mutex protects mark from getting detached and thus also from
         * mark->connector->obj getting NULL.
         */
        if (chunk->dead || !(entry->flags & FSNOTIFY_MARK_FLAG_ATTACHED)) {
-               spin_unlock(&entry->lock);
                mutex_unlock(&entry->group->mark_mutex);
                if (new)
                        fsnotify_put_mark(&new->mark);
@@ -280,7 +278,6 @@ static void untag_chunk(struct node *p)
                list_del_init(&p->list);
                list_del_rcu(&chunk->hash);
                spin_unlock(&hash_lock);
-               spin_unlock(&entry->lock);
                mutex_unlock(&entry->group->mark_mutex);
                fsnotify_destroy_mark(entry, audit_tree_group);
                goto out;
@@ -323,7 +320,6 @@ static void untag_chunk(struct node *p)
        list_for_each_entry(owner, &new->trees, same_root)
                owner->root = new;
        spin_unlock(&hash_lock);
-       spin_unlock(&entry->lock);
        mutex_unlock(&entry->group->mark_mutex);
        fsnotify_destroy_mark(entry, audit_tree_group);
        fsnotify_put_mark(&new->mark);  /* drop initial reference */
@@ -340,7 +336,6 @@ Fallback:
        p->owner = NULL;
        put_tree(owner);
        spin_unlock(&hash_lock);
-       spin_unlock(&entry->lock);
        mutex_unlock(&entry->group->mark_mutex);
 out:
        fsnotify_put_mark(entry);
@@ -360,12 +355,12 @@ static int create_chunk(struct inode *inode, struct audit_tree *tree)
                return -ENOSPC;
        }
 
-       spin_lock(&entry->lock);
+       mutex_lock(&entry->group->mark_mutex);
        spin_lock(&hash_lock);
        if (tree->goner) {
                spin_unlock(&hash_lock);
                chunk->dead = 1;
-               spin_unlock(&entry->lock);
+               mutex_unlock(&entry->group->mark_mutex);
                fsnotify_destroy_mark(entry, audit_tree_group);
                fsnotify_put_mark(entry);
                return 0;
@@ -380,7 +375,7 @@ static int create_chunk(struct inode *inode, struct audit_tree *tree)
        }
        insert_hash(chunk);
        spin_unlock(&hash_lock);
-       spin_unlock(&entry->lock);
+       mutex_unlock(&entry->group->mark_mutex);
        fsnotify_put_mark(entry);       /* drop initial reference */
        return 0;
 }
@@ -421,14 +416,12 @@ static int tag_chunk(struct inode *inode, struct audit_tree *tree)
        chunk_entry = &chunk->mark;
 
        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->obj getting NULL.
         */
        if (!(old_entry->flags & FSNOTIFY_MARK_FLAG_ATTACHED)) {
                /* old_entry is being shot, lets just lie */
-               spin_unlock(&old_entry->lock);
                mutex_unlock(&old_entry->group->mark_mutex);
                fsnotify_put_mark(old_entry);
                fsnotify_put_mark(&chunk->mark);
@@ -437,23 +430,16 @@ static int tag_chunk(struct inode *inode, struct audit_tree *tree)
 
        if (fsnotify_add_mark_locked(chunk_entry, old_entry->connector->obj,
                                     FSNOTIFY_OBJ_TYPE_INODE, 1)) {
-               spin_unlock(&old_entry->lock);
                mutex_unlock(&old_entry->group->mark_mutex);
                fsnotify_put_mark(chunk_entry);
                fsnotify_put_mark(old_entry);
                return -ENOSPC;
        }
 
-       /* even though we hold old_entry->lock, this is safe since chunk_entry->lock could NEVER have been grabbed before */
-       spin_lock(&chunk_entry->lock);
        spin_lock(&hash_lock);
-
-       /* we now hold old_entry->lock, chunk_entry->lock, and hash_lock */
        if (tree->goner) {
                spin_unlock(&hash_lock);
                chunk->dead = 1;
-               spin_unlock(&chunk_entry->lock);
-               spin_unlock(&old_entry->lock);
                mutex_unlock(&old_entry->group->mark_mutex);
 
                fsnotify_destroy_mark(chunk_entry, audit_tree_group);
@@ -485,8 +471,6 @@ static int tag_chunk(struct inode *inode, struct audit_tree *tree)
                list_add(&tree->same_root, &chunk->trees);
        }
        spin_unlock(&hash_lock);
-       spin_unlock(&chunk_entry->lock);
-       spin_unlock(&old_entry->lock);
        mutex_unlock(&old_entry->group->mark_mutex);
        fsnotify_destroy_mark(old_entry, audit_tree_group);
        fsnotify_put_mark(chunk_entry); /* drop initial reference */