Commit 2622649a authored by Matthew Brost's avatar Matthew Brost
Browse files

dma-buf: Assign separate lockdep class to array lock 



dma_fence_array_enable_signaling() runs while holding the array
inline_lock and may add callbacks to underlying fences, which takes
their inline_lock.

Since both locks share the same lockdep class, this valid nesting
triggers a recursive locking warning. Assign a distinct lockdep class
to the array inline_lock so lockdep can correctly model the hierarchy.

Fixes: 59432439 ("dma-buf: use inline lock for the dma-fence-array")
Cc: Christian König <christian.koenig@amd.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@igalia.com>
Cc: Philipp Stanner <phasta@kernel.org>
Cc: Boris Brezillon <boris.brezillon@collabora.com>
Signed-off-by: default avatarMatthew Brost <matthew.brost@intel.com>
Reviewed-by: default avatarChristian König <christian.koenig@amd.com>
Link: https://patch.msgid.link/20260224183922.2256492-2-matthew.brost@intel.com
parent 2ec86535

drivers/dma-buf/dma-fence-array.c

+14 −0
Original line number Diff line number Diff line
@@ -200,6 +200,8 @@ void dma_fence_array_init(struct dma_fence_array *array, 
			  u64 context, unsigned seqno,

			  bool signal_on_any)

{

	static struct lock_class_key dma_fence_array_lock_key;



	WARN_ON(!num_fences || !fences);



	array->num_fences = num_fences;
@@ -208,6 +210,18 @@ void dma_fence_array_init(struct dma_fence_array *array, 
		       seqno);

	init_irq_work(&array->work, irq_dma_fence_array_work);



	/*

	 * dma_fence_array_enable_signaling() is invoked while holding

	 * array->base.inline_lock and may call dma_fence_add_callback()

	 * on the underlying fences, which takes their inline_lock.

	 *

	 * Since both locks share the same lockdep class, this legitimate

	 * nesting confuses lockdep and triggers a recursive locking

	 * warning. Assign a separate lockdep class to the array lock

	 * to model this hierarchy correctly.

	 */

	lockdep_set_class(&array->base.inline_lock, &dma_fence_array_lock_key);



	atomic_set(&array->num_pending, signal_on_any ? 1 : num_fences);

	array->fences = fences;