drm/amdgpu: fix error handling in amdgpu_cs_process_fence_dep

We always need to drop the ctx reference and should check
for errors first and then dereference the fence pointer.
Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Chunming Zhou <david1.zhou@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c

@@ -1044,30 +1044,28 @@ static int amdgpu_cs_process_fence_dep(struct amdgpu_cs_parser *p,
 			return r;
 		}
 
-		fence = amdgpu_ctx_get_fence(ctx, entity,
-					     deps[i].handle);
+		fence = amdgpu_ctx_get_fence(ctx, entity, deps[i].handle);
+		amdgpu_ctx_put(ctx);
+
+		if (IS_ERR(fence))
+			return PTR_ERR(fence);
+		else if (!fence)
+			continue;
 
 		if (chunk->chunk_id == AMDGPU_CHUNK_ID_SCHEDULED_DEPENDENCIES) {
-			struct drm_sched_fence *s_fence = to_drm_sched_fence(fence);
+			struct drm_sched_fence *s_fence;
 			struct dma_fence *old = fence;
 
+			s_fence = to_drm_sched_fence(fence);
 			fence = dma_fence_get(&s_fence->scheduled);
 			dma_fence_put(old);
 		}
 
-		if (IS_ERR(fence)) {
-			r = PTR_ERR(fence);
-			amdgpu_ctx_put(ctx);
-			return r;
-		} else if (fence) {
-			r = amdgpu_sync_fence(p->adev, &p->job->sync, fence,
-					true);
+		r = amdgpu_sync_fence(p->adev, &p->job->sync, fence, true);
 		dma_fence_put(fence);
-			amdgpu_ctx_put(ctx);
 		if (r)
 			return r;
 	}
-	}
 	return 0;
 }