[PATCH 5.15 245/279] drm/i915/guc: Unwind context requests in reverse order

[Greg Kroah-Hartman]

From: Matthew Brost <matthew.brost@xxxxxxxxx>

commit c39f51cc980dd918c5b3da61d54c4725785e766e upstream.

When unwinding requests on a reset context, if other requests in the
context are in the priority list the requests could be resubmitted out
of seqno order. Traverse the list of active requests in reverse and
append to the head of the priority list to fix this.

Fixes: eb5e7da736f3 ("drm/i915/guc: Reset implementation for new GuC interface")
Signed-off-by: Matthew Brost <matthew.brost@xxxxxxxxx>
Reviewed-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@xxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: John Harrison <John.C.Harrison@xxxxxxxxx>
Link: https://patchwork.freedesktop.org/patch/msgid/20210909164744.31249-4-matthew.brost@xxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c |    8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

--- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
+++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
@@ -807,9 +807,9 @@ __unwind_incomplete_requests(struct inte
 
 	spin_lock_irqsave(&sched_engine->lock, flags);
 	spin_lock(&ce->guc_active.lock);
-	list_for_each_entry_safe(rq, rn,
-				 &ce->guc_active.requests,
-				 sched.link) {
+	list_for_each_entry_safe_reverse(rq, rn,
+					 &ce->guc_active.requests,
+					 sched.link) {
 		if (i915_request_completed(rq))
 			continue;
 
@@ -824,7 +824,7 @@ __unwind_incomplete_requests(struct inte
 		}
 		GEM_BUG_ON(i915_sched_engine_is_empty(sched_engine));
 
-		list_add_tail(&rq->sched.link, pl);
+		list_add(&rq->sched.link, pl);
 		set_bit(I915_FENCE_FLAG_PQUEUE, &rq->fence.flags);
 	}
 	spin_unlock(&ce->guc_active.lock);