@@ -176,16 +176,32 @@ static void drm_sched_entity_kill_jobs_cb(struct dma_fence *f,
{
struct drm_sched_job *job = container_of(cb, struct drm_sched_job,
finish_cb);
- int r;
+ unsigned long index;
dma_fence_put(f);
/* Wait for all dependencies to avoid data corruptions */
- while (!xa_empty(&job->dependencies)) {
- f = xa_erase(&job->dependencies, job->last_dependency++);
- r = dma_fence_add_callback(f, &job->finish_cb,
- drm_sched_entity_kill_jobs_cb);
- if (!r)
+ xa_for_each(&job->dependencies, index, f) {
+ struct drm_sched_fence *s_fence = to_drm_sched_fence(f);
+
+ if (s_fence && f == &s_fence->scheduled) {
+ /* The dependencies array had a reference on the scheduled
+ * fence, and the finished fence refcount might have
+ * dropped to zero. Use dma_fence_get_rcu() so we get
+ * a NULL fence in that case.
+ */
+ f = dma_fence_get_rcu(&s_fence->finished);
+
+ /* Now that we have a reference on the finished fence,
+ * we can release the reference the dependencies array
+ * had on the scheduled fence.
+ */
+ dma_fence_put(&s_fence->scheduled);
+ }
+
+ xa_erase(&job->dependencies, index);
+ if (f && !dma_fence_add_callback(f, &job->finish_cb,
+ drm_sched_entity_kill_jobs_cb))
return;
dma_fence_put(f);
@@ -415,8 +431,17 @@ static struct dma_fence *
drm_sched_job_dependency(struct drm_sched_job *job,
struct drm_sched_entity *entity)
{
- if (!xa_empty(&job->dependencies))
- return xa_erase(&job->dependencies, job->last_dependency++);
+ struct dma_fence *f;
+
+ /* We keep the fence around, so we can iterate over all dependencies
+ * in drm_sched_entity_kill_jobs_cb() to ensure all deps are signaled
+ * before killing the job.
+ */
+ f = xa_load(&job->dependencies, job->last_dependency);
+ if (f) {
+ job->last_dependency++;
+ return dma_fence_get(f);
+ }
if (job->sched->ops->prepare_job)
return job->sched->ops->prepare_job(job, entity);
drm_sched_entity_kill_jobs_cb() logic is omitting the last fence popped from the dependency array that was waited upon before drm_sched_entity_kill() was called (drm_sched_entity::dependency field), so we're basically waiting for all dependencies except one. In theory, this wait shouldn't be needed because resources should have their users registered to the dma_resv object, thus guaranteeing that future jobs wanting to access these resources wait on all the previous users (depending on the access type, of course). But we want to keep these explicit waits in the kill entity path just in case. Let's make sure we keep all dependencies in the array in drm_sched_job_dependency(), so we can iterate over the array and wait in drm_sched_entity_kill_jobs_cb(). We also make sure we wait on drm_sched_fence::finished if we were originally asked to wait on drm_sched_fence::scheduled. In that case, we assume the intent was to delegate the wait to the firmware/GPU or rely on the pipelining done at the entity/scheduler level, but when killing jobs, we really want to wait for completion not just scheduling. v4: - Fix commit message - Fix a use-after-free bug v3: - Always wait for drm_sched_fence::finished fences in drm_sched_entity_kill_jobs_cb() when we see a sched_fence v2: - Don't evict deps in drm_sched_job_dependency() Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com> Suggested-by: "Christian König" <christian.koenig@amd.com> Cc: Frank Binns <frank.binns@imgtec.com> Cc: Sarah Walker <sarah.walker@imgtec.com> Cc: Donald Robson <donald.robson@imgtec.com> Cc: Luben Tuikov <luben.tuikov@amd.com> Cc: David Airlie <airlied@gmail.com> Cc: Daniel Vetter <daniel@ffwll.ch> Cc: Sumit Semwal <sumit.semwal@linaro.org> Cc: "Christian König" <christian.koenig@amd.com> --- drivers/gpu/drm/scheduler/sched_entity.c | 41 +++++++++++++++++++----- 1 file changed, 33 insertions(+), 8 deletions(-)