[PATCH] drm/amdgpu: Fix the null pointer issue for tdr

[Emily Deng]

When the job is already signaled, the s_fence is freed. Then it will has
null pointer in amdgpu_device_gpu_recover.

Signed-off-by: Emily Deng <Emily.Deng at amd.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_device.c |  2 +-
 drivers/gpu/drm/scheduler/sched_main.c     | 11 ++++++-----
 2 files changed, 7 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
index e6ce949..5a8f08e 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
@@ -4075,7 +4075,7 @@ int amdgpu_device_gpu_recover(struct amdgpu_device *adev,
 	 *
 	 * job->base holds a reference to parent fence
 	 */
-	if (job && job->base.s_fence->parent &&
+	if (job && job->base.s_fence && job->base.s_fence->parent &&
 	    dma_fence_is_signaled(job->base.s_fence->parent))
 		job_signaled = true;
 
diff --git a/drivers/gpu/drm/scheduler/sched_main.c b/drivers/gpu/drm/scheduler/sched_main.c
index 31809ca..56cc10e 100644
--- a/drivers/gpu/drm/scheduler/sched_main.c
+++ b/drivers/gpu/drm/scheduler/sched_main.c
@@ -334,8 +334,8 @@ void drm_sched_increase_karma(struct drm_sched_job *bad)
 
 			spin_lock(&rq->lock);
 			list_for_each_entry_safe(entity, tmp, &rq->entities, list) {
-				if (bad->s_fence->scheduled.context ==
-				    entity->fence_context) {
+				if (bad->s_fence && (bad->s_fence->scheduled.context ==
+				    entity->fence_context)) {
 					if (atomic_read(&bad->karma) >
 					    bad->sched->hang_limit)
 						if (entity->guilty)
@@ -376,7 +376,7 @@ void drm_sched_stop(struct drm_gpu_scheduler *sched, struct drm_sched_job *bad)
 	 * This iteration is thread safe as sched thread is stopped.
 	 */
 	list_for_each_entry_safe_reverse(s_job, tmp, &sched->ring_mirror_list, node) {
-		if (s_job->s_fence->parent &&
+		if (s_job->s_fence && s_job->s_fence->parent &&
 		    dma_fence_remove_callback(s_job->s_fence->parent,
 					      &s_job->cb)) {
 			atomic_dec(&sched->hw_rq_count);
@@ -395,7 +395,8 @@ void drm_sched_stop(struct drm_gpu_scheduler *sched, struct drm_sched_job *bad)
 			 *
 			 * Job is still alive so fence refcount at least 1
 			 */
-			dma_fence_wait(&s_job->s_fence->finished, false);
+			if (s_job->s_fence)
+				dma_fence_wait(&s_job->s_fence->finished, false);
 
 			/*
 			 * We must keep bad job alive for later use during
@@ -438,7 +439,7 @@ void drm_sched_start(struct drm_gpu_scheduler *sched, bool full_recovery)
 	 * GPU recovers can't run in parallel.
 	 */
 	list_for_each_entry_safe(s_job, tmp, &sched->ring_mirror_list, node) {
-		struct dma_fence *fence = s_job->s_fence->parent;
+		struct dma_fence *fence = s_job->s_fence ? s_job->s_fence->parent : NULL;
 
 		atomic_inc(&sched->hw_rq_count);
 
-- 
2.7.4