drm/i915/execlists: Only mark incomplete requests as -EIO on cancelling

Only the requests that have not completed do we want to change the
status of to signal the -EIO when cancelling the inflight set of requests
upon wedging.

Reported-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191011103345.26013-1-chris@chris-wilson.co.uk

drivers/gpu/drm/i915/gt/intel_lrc.c

@@ -247,8 +247,12 @@ static void __context_pin_release(struct intel_context *ce)
 
 static void mark_eio(struct i915_request *rq)
 {
-	if (!i915_request_signaled(rq))
-		dma_fence_set_error(&rq->fence, -EIO);
+	if (i915_request_completed(rq))
+		return;
+
+	GEM_BUG_ON(i915_request_signaled(rq));
+
+	dma_fence_set_error(&rq->fence, -EIO);
 	i915_request_mark_complete(rq);
 }