[PATCH] drm/i915/gt/uc: Evaluate GuC priority within locks

[Andi Shyti <andi.shyti@linux.intel.com>]

The ce->guc_state.lock was made to protect guc_prio, which
indicates the GuC priority level.

But at the begnning of the function we perform some sanity check
of guc_prio outside its protected section. Move them within the
locked region.

Use this occasion to expand the if statement to make it clearer.

Signed-off-by: Andi Shyti <andi.shyti@linux.intel.com>
Cc: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Matthew Brost <matthew.brost@intel.com>
---
Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>

Changelog
=========
 - Removed the stable tags as this path is not normally under
   multi task stress.
 - Refactored the if statements in order to remove unnecessary
   checks (thanks, Daniele)
 - Added Matt's r-b.


 .../gpu/drm/i915/gt/uc/intel_guc_submission.c | 27 +++++++++++--------
 1 file changed, 16 insertions(+), 11 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 0eaa1064242c..9400d0eb682b 100644
--- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
+++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
@@ -4267,20 +4267,25 @@ static void guc_bump_inflight_request_prio(struct i915_request *rq,
 	u8 new_guc_prio = map_i915_prio_to_guc_prio(prio);
 
 	/* Short circuit function */
-	if (prio < I915_PRIORITY_NORMAL ||
-	    rq->guc_prio == GUC_PRIO_FINI ||
-	    (rq->guc_prio != GUC_PRIO_INIT &&
-	     !new_guc_prio_higher(rq->guc_prio, new_guc_prio)))
+	if (prio < I915_PRIORITY_NORMAL)
 		return;
 
 	spin_lock(&ce->guc_state.lock);
-	if (rq->guc_prio != GUC_PRIO_FINI) {
-		if (rq->guc_prio != GUC_PRIO_INIT)
-			sub_context_inflight_prio(ce, rq->guc_prio);
-		rq->guc_prio = new_guc_prio;
-		add_context_inflight_prio(ce, rq->guc_prio);
-		update_context_prio(ce);
-	}
+
+	if (rq->guc_prio == GUC_PRIO_FINI)
+		goto exit;
+
+	if (!new_guc_prio_higher(rq->guc_prio, new_guc_prio))
+		goto exit;
+
+	if (rq->guc_prio != GUC_PRIO_INIT)
+		sub_context_inflight_prio(ce, rq->guc_prio);
+
+	rq->guc_prio = new_guc_prio;
+	add_context_inflight_prio(ce, rq->guc_prio);
+	update_context_prio(ce);
+
+exit:
 	spin_unlock(&ce->guc_state.lock);
 }
 
-- 
2.45.1