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

intel_guc_find_hung_context() was not acquiring the correct spinlock
before searching the request list. So fix that up. While at it, add
some extra whitespace padding for readability.

Fixes: dc0dad3 ("drm/i915/guc: Fix for error capture after full GPU reset with GuC")
Signed-off-by: John Harrison <[email protected]>
Reviewed-by: Daniele Ceraolo Spurio <[email protected]>
Acked-by: Tvrtko Ursulin <[email protected]>
Cc: Matthew Brost <[email protected]>
Cc: Jani Nikula <[email protected]>
Cc: Joonas Lahtinen <[email protected]>
Cc: Rodrigo Vivi <[email protected]>
Cc: Matt Roper <[email protected]>
Cc: Umesh Nerlige Ramappa <[email protected]>
Cc: Michael Cheng <[email protected]>
Cc: Lucas De Marchi <[email protected]>
Cc: Tejas Upadhyay <[email protected]>
Cc: Chris Wilson <[email protected]>
Cc: Bruce Chang <[email protected]>
Cc: Alan Previn <[email protected]>
Cc: Matthew Auld <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]
(cherry picked from commit d1c3717)
Signed-off-by: Rodrigo Vivi <[email protected]>

Author: johnharr-intel

drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c

@@ -4817,6 +4817,8 @@ 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;
 
@@ -4833,17 +4835,26 @@ 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... */
 			intel_context_put(ce);
 			xa_lock(&guc->context_lookup);
 			goto done;
 		}
+
 next:
 		intel_context_put(ce);
 		xa_lock(&guc->context_lookup);