From 0568a4086a6c7386885eb2ac2dae3f7186eb503f Mon Sep 17 00:00:00 2001 From: Niranjana Vishwanathapura Date: Wed, 29 May 2024 15:16:39 -0700 Subject: [PATCH] drm/xe: Remove unwanted mutex locking Do not hold xef->exec_queue.lock mutex while parsing the xarray xef->exec_queue.xa in xe_file_close() as it is not needed and will cause an unwanted dependency between this lock and the vm->lock. This lock protects the exec queue lookup and reference taking which doesn't apply to this code path. When FD is closing, IOCTLs presumably can't be modifying the xarray. v2: Update commit text (Matt Brost) v3: Add more code comment (Rodrigo Vivi) v4: Further expand code comment (Rodirgo Vivi) Signed-off-by: Niranjana Vishwanathapura Reviewed-by: Matthew Brost Reviewed-by: Jagmeet Randhawa Acked-by: Rodrigo Vivi Signed-off-by: Matthew Brost Link: https://patchwork.freedesktop.org/patch/msgid/20240529221639.23117-1-niranjana.vishwanathapura@intel.com --- drivers/gpu/drm/xe/xe_device.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/xe/xe_device.c b/drivers/gpu/drm/xe/xe_device.c index b2d5c7341238..d1560f5d4b84 100644 --- a/drivers/gpu/drm/xe/xe_device.c +++ b/drivers/gpu/drm/xe/xe_device.c @@ -95,12 +95,16 @@ static void xe_file_close(struct drm_device *dev, struct drm_file *file) struct xe_exec_queue *q; unsigned long idx; - mutex_lock(&xef->exec_queue.lock); + /* + * No need for exec_queue.lock here as there is no contention for it + * when FD is closing as IOCTLs presumably can't be modifying the + * xarray. Taking exec_queue.lock here causes undue dependency on + * vm->lock taken during xe_exec_queue_kill(). + */ xa_for_each(&xef->exec_queue.xa, idx, q) { xe_exec_queue_kill(q); xe_exec_queue_put(q); } - mutex_unlock(&xef->exec_queue.lock); xa_destroy(&xef->exec_queue.xa); mutex_destroy(&xef->exec_queue.lock); mutex_lock(&xef->vm.lock);