From c39f51cc980dd918c5b3da61d54c4725785e766e Mon Sep 17 00:00:00 2001
From: Matthew Brost <matthew.brost@intel.com>
Date: Thu, 9 Sep 2021 09:47:24 -0700
Subject: drm/i915/guc: Unwind context requests in reverse order
Git-commit: c39f51cc980dd918c5b3da61d54c4725785e766e
Patch-mainline: v5.16-rc1
References: git-fixes

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@intel.com>
Reviewed-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210909164744.31249-4-matthew.brost@intel.com
Signed-off-by: Patrik Jakobsson <pjakobsson@suse.de>
---
 drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
index aff5dd247a88..0c1e6b465fba 100644
--- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
+++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
@@ -806,9 +806,9 @@ __unwind_incomplete_requests(struct intel_context *ce)
 
 	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;
 
@@ -825,7 +825,7 @@ __unwind_incomplete_requests(struct intel_context *ce)
 		}
 		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_lock(&ce->guc_active.lock);
-- 
2.33.1