From: jsg <jsg@openbsd.org>
Date: Fri, 10 Feb 2023 14:27:01 +0000 (+0000)
Subject: drm/i915/guc: Fix locking when searching for a hung request
X-Git-Url: http://artulab.com/gitweb/?a=commitdiff_plain;h=5d4146b4b020d3b4ac8fbbbd00d4d63ccf41610e;p=openbsd

drm/i915/guc: Fix locking when searching for a hung request

From John Harrison
de997938a7a5da3cb3bd3b914456656963ca1d1c in linux-6.1.y/6.1.11
87b04e53daf806945c415e94de9f90943d434aed in mainline linux
---

diff --git a/sys/dev/pci/drm/i915/gt/uc/intel_guc_submission.c b/sys/dev/pci/drm/i915/gt/uc/intel_guc_submission.c
index 8874cb32a70..418fe6f8f98 100644
--- a/sys/dev/pci/drm/i915/gt/uc/intel_guc_submission.c
+++ b/sys/dev/pci/drm/i915/gt/uc/intel_guc_submission.c
@@ -4597,6 +4597,8 @@ void intel_guc_find_hung_context(struct intel_engine_cs *engine)
 
 	xa_lock_irqsave(&guc->context_lookup, flags);
 	xa_for_each(&guc->context_lookup, index, ce) {
+		bool found;
+
 		if (!kref_get_unless_zero(&ce->ref))
 			continue;
 
@@ -4613,10 +4615,18 @@ void intel_guc_find_hung_context(struct intel_engine_cs *engine)
 				goto next;
 		}
 
+		found = false;
+		spin_lock(&ce->guc_state.lock);
 		list_for_each_entry(rq, &ce->guc_state.requests, sched.link) {
 			if (i915_test_request_state(rq) != I915_REQUEST_ACTIVE)
 				continue;
 
+			found = true;
+			break;
+		}
+		spin_unlock(&ce->guc_state.lock);
+
+		if (found) {
 			intel_engine_set_hung_context(engine, ce);
 
 			/* Can only cope with one hang at a time... */
@@ -4624,6 +4634,7 @@ void intel_guc_find_hung_context(struct intel_engine_cs *engine)
 			xa_lock(&guc->context_lookup);
 			goto done;
 		}
+
 next:
 		intel_context_put(ce);
 		xa_lock(&guc->context_lookup);