drm/xe: Use ordered wq for preempt fence waiting

Preempt fences can sleep waiting for an exec queue suspend operation to
complete. If the system_unbound_wq is used for waiting and the number of
waiters exceeds max_active this will result in other users of the
system_unbound_wq getting starved. Use a device private work queue for
preempt fences to avoid starvation of the system_unbound_wq.

Even though suspend operations can complete out-of-order, all suspend
operations within a VM need to complete before the preempt rebind worker
can start. With that, use a device private ordered wq for preempt fence
waiting.

v2:
 - Add comment about cleanup on failure (Matt R)
 - Update commit message (Lucas)

Fixes: dd08ebf6c352 ("drm/xe: Introduce a new DRM driver for Intel GPUs")
Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240401221913.139672-2-matthew.brost@intel.com
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/drivers/gpu/drm/xe/xe_preempt_fence.c b/drivers/gpu/drm/xe/xe_preempt_fence.c
index 7bce2a332603..7d50c6e89d8e 100644
--- a/drivers/gpu/drm/xe/xe_preempt_fence.c
+++ b/drivers/gpu/drm/xe/xe_preempt_fence.c
@@ -49,7 +49,7 @@ static bool preempt_fence_enable_signaling(struct dma_fence *fence)
 	struct xe_exec_queue *q = pfence->q;
 
 	pfence->error = q->ops->suspend(q);
-	queue_work(system_unbound_wq, &pfence->preempt_work);
+	queue_work(q->vm->xe->preempt_fence_wq, &pfence->preempt_work);
 	return true;
 }