Lin I explicitly pointed out that you should *not* send it to stable@vger.kernel.org.
Greg and other stable maintainers please ignore this mail, the bug fix is going upstream through the normal DRM channels.
Regards, Christian.
On 17.07.25 10:34, Lin.Cao wrote:
When application A submits jobs and application B submits a job with a dependency on A's fence, the normal flow wakes up the scheduler after processing each job. However, the optimization in drm_sched_entity_add_dependency_cb() uses a callback that only clears dependencies without waking up the scheduler.
When application A is killed before its jobs can run, the callback gets triggered but only clears the dependency without waking up the scheduler, causing the scheduler to enter sleep state and application B to hang.
Remove the optimization by deleting drm_sched_entity_clear_dep() and its usage, ensuring the scheduler is always woken up when dependencies are cleared.
Fixes: 777dbd458c89 ("drm/amdgpu: drop a dummy wakeup scheduler") Cc: stable@vger.kernel.org # v4.6+
Signed-off-by: Lin.Cao lincao12@amd.com Reviewed-by: Christian König christian.koenig@amd.com
drivers/gpu/drm/scheduler/sched_entity.c | 21 ++------------------- 1 file changed, 2 insertions(+), 19 deletions(-)
diff --git a/drivers/gpu/drm/scheduler/sched_entity.c b/drivers/gpu/drm/scheduler/sched_entity.c index e671aa241720..ac678de7fe5e 100644 --- a/drivers/gpu/drm/scheduler/sched_entity.c +++ b/drivers/gpu/drm/scheduler/sched_entity.c @@ -355,17 +355,6 @@ void drm_sched_entity_destroy(struct drm_sched_entity *entity) } EXPORT_SYMBOL(drm_sched_entity_destroy); -/* drm_sched_entity_clear_dep - callback to clear the entities dependency */ -static void drm_sched_entity_clear_dep(struct dma_fence *f,
struct dma_fence_cb *cb)-{
- struct drm_sched_entity *entity =
container_of(cb, struct drm_sched_entity, cb);- entity->dependency = NULL;
- dma_fence_put(f);
-}
/*
- drm_sched_entity_wakeup - callback to clear the entity's dependency and
- wake up the scheduler
@@ -376,7 +365,8 @@ static void drm_sched_entity_wakeup(struct dma_fence *f, struct drm_sched_entity *entity = container_of(cb, struct drm_sched_entity, cb);
- drm_sched_entity_clear_dep(f, cb);
- entity->dependency = NULL;
- dma_fence_put(f); drm_sched_wakeup(entity->rq->sched);
} @@ -429,13 +419,6 @@ static bool drm_sched_entity_add_dependency_cb(struct drm_sched_entity *entity) fence = dma_fence_get(&s_fence->scheduled); dma_fence_put(entity->dependency); entity->dependency = fence;
if (!dma_fence_add_callback(fence, &entity->cb,drm_sched_entity_clear_dep))return true;/* Ignore it when it is already scheduled */dma_fence_put(fence);return false;if (!dma_fence_add_callback(entity->dependency, &entity->cb,