drm/msm: Fix a fence leak in submit error path

In error paths, we could unref the submit without calling
drm_sched_entity_push_job(), so msm_job_free() will never get
called.  Since drm_sched_job_cleanup() will NULL out the
s_fence, we can use that to detect this case.

Signed-off-by: Rob Clark <robdclark@chromium.org>
Patchwork: https://patchwork.freedesktop.org/patch/653584/
Signed-off-by: Rob Clark <robin.clark@oss.qualcomm.com>

Author: robclark

drivers/gpu/drm/msm/msm_gem_submit.c

@@ -85,6 +85,15 @@ void __msm_gem_submit_destroy(struct kref *kref)
 			container_of(kref, struct msm_gem_submit, ref);
 	unsigned i;
 
+	/*
+	 * In error paths, we could unref the submit without calling
+	 * drm_sched_entity_push_job(), so msm_job_free() will never
+	 * get called.  Since drm_sched_job_cleanup() will NULL out
+	 * s_fence, we can use that to detect this case.
+	 */
+	if (submit->base.s_fence)
+		drm_sched_job_cleanup(&submit->base);
+
 	if (submit->fence_id) {
 		spin_lock(&submit->queue->idr_lock);
 		idr_remove(&submit->queue->fence_idr, submit->fence_id);