drm/msm/gpu: Skip retired submits in recover worker

If we somehow raced with submit retiring, either while waiting for
worker to have a chance to run or acquiring the gpu lock, then the
recover worker should just bail.
Signed-off-by: Rob Clark <robdclark@chromium.org>
Patchwork: https://patchwork.freedesktop.org/patch/568034/

drivers/gpu/drm/msm/msm_gpu.c

@@ -365,7 +365,14 @@ static void recover_worker(struct kthread_work *work)
 	DRM_DEV_ERROR(dev->dev, "%s: hangcheck recover!\n", gpu->name);
 
 	submit = find_submit(cur_ring, cur_ring->memptrs->fence + 1);
-	if (submit) {
+
+	/*
+	 * If the submit retired while we were waiting for the worker to run,
+	 * or waiting to acquire the gpu lock, then nothing more to do.
+	 */
+	if (!submit)
+		goto out_unlock;
+
 	/* Increment the fault counts */
 	submit->queue->faults++;
 	if (submit->aspace)
@@ -380,15 +387,10 @@ static void recover_worker(struct kthread_work *work)
 		msm_rd_dump_submit(priv->hangrd, submit,
 				   "offending task: %s (%s)", comm, cmd);
 	} else {
+		DRM_DEV_ERROR(dev->dev, "%s: offending task: unknown\n", gpu->name);
+
 		msm_rd_dump_submit(priv->hangrd, submit, NULL);
 	}
-	} else {
-		/*
-		 * We couldn't attribute this fault to any particular context,
-		 * so increment the global fault count instead.
-		 */
-		gpu->global_faults++;
-	}
 
 	/* Record the crash state */
 	pm_runtime_get_sync(&gpu->pdev->dev);
@@ -440,6 +442,7 @@ static void recover_worker(struct kthread_work *work)
 
 	pm_runtime_put(&gpu->pdev->dev);
 
+out_unlock:
 	mutex_unlock(&gpu->lock);
 
 	msm_gpu_retire(gpu);