Commit 9f16d2e6 authored by Jan Kara's avatar Jan Kara Committed by Paul Moore
Browse files

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: default avatarRichard Guy Briggs <rgb@redhat.com>
Signed-off-by: default avatarJan Kara <jack@suse.cz>
Signed-off-by: default avatarPaul Moore <paul@paul-moore.com>
parent ea956d8b

kernel/audit_tree.c

+4 −20
Original line number Diff line number Diff line
@@ -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 */

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