5.4-stable review patch. If anyone has any objections, please let me know.
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From: "Lin.Cao" lincao12@amd.com
[ Upstream commit 15f77764e90a713ee3916ca424757688e4f565b9 ]
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 Signed-off-by: Philipp Stanner phasta@kernel.org Link: https://lore.kernel.org/r/20250717084453.921097-1-lincao12@amd.com [ adjusted context ] Signed-off-by: Sasha Levin sashal@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/gpu/drm/scheduler/sched_entity.c | 23 ++--------------------- 1 file changed, 2 insertions(+), 21 deletions(-)
--- a/drivers/gpu/drm/scheduler/sched_entity.c +++ b/drivers/gpu/drm/scheduler/sched_entity.c @@ -328,19 +328,6 @@ void drm_sched_entity_destroy(struct drm 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_clear_dep - callback to clear the entities dependency and * wake up scheduler */ @@ -350,7 +337,8 @@ static void drm_sched_entity_wakeup(stru 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); }
@@ -426,13 +414,6 @@ static bool drm_sched_entity_add_depende 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,