[PATCH 6/9] drm/i915/guc: Do not clear enable during reset in an enable is inflight

[Matthew Brost]

Do not clear enable during a context reset if a schedule enable is in
flight. This can occur if the context reset during a request
cancellation, clears the offending request, and then enables scheduling.

Fixes: 62eaf0ae217d ("drm/i915/guc: Support request cancellation")
Signed-off-by: Matthew Brost <matthew.brost at intel.com>
Cc: <stable at vger.kernel.org
---
 .../gpu/drm/i915/gt/uc/intel_guc_submission.c    | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 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 e5eb2df11b4a..4631b15eccaf 100644
--- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
+++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
@@ -831,17 +831,23 @@ __unwind_incomplete_requests(struct intel_context *ce)
 static void __guc_reset_context(struct intel_context *ce, bool stalled)
 {
 	struct i915_request *rq;
+	unsigned long flags;
 	u32 head;
 
 	intel_context_get(ce);
 
 	/*
-	 * GuC will implicitly mark the context as non-schedulable
-	 * when it sends the reset notification. Make sure our state
-	 * reflects this change. The context will be marked enabled
-	 * on resubmission.
+	 * GuC will implicitly mark the context as non-schedulable when it sends
+	 * the reset notification. Make sure our state reflects this change. The
+	 * context will be marked enabled on resubmission. A small window exists
+	 * where the context could be block & unblocked (scheduling enable) while
+	 * this reset was inflight. If a scheduling enable is already is in
+	 * flight do not clear the enable.
 	 */
-	clr_context_enabled(ce);
+	spin_lock_irqsave(&ce->guc_state.lock, flags);
+	if (!context_pending_enable(ce))
+		clr_context_enabled(ce);
+	spin_unlock_irqrestore(&ce->guc_state.lock, flags);
 
 	rq = intel_context_find_active_request(ce);
 	if (!rq) {
-- 
2.32.0