From: Nicolai Hähnle Date: Wed, 2 Dec 2015 16:35:12 +0000 (+0100) Subject: drm/amdgpu: fix race condition in amd_sched_entity_push_job X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=07df04dfcfe51a45239d056d43cbc09702262c82;p=GitHub%2Fmoto-9609%2Fandroid_kernel_motorola_exynos9610.git drm/amdgpu: fix race condition in amd_sched_entity_push_job As soon as we leave the spinlock after the job has been added to the job queue, we can no longer rely on the job's data to be available. I have seen a null-pointer dereference due to sched == NULL in amd_sched_wakeup via amd_sched_entity_push_job and amd_sched_ib_submit_kernel_helper. Since the latter initializes sched_job->sched with the address of the ring scheduler, which is guaranteed to be non-NULL, this race appears to be a likely culprit. Signed-off-by: Nicolai Hähnle Bugzilla: https://bugs.freedesktop.org/attachment.cgi?bugid=93079 Reviewed-by: Christian König --- diff --git a/drivers/gpu/drm/amd/scheduler/gpu_scheduler.c b/drivers/gpu/drm/amd/scheduler/gpu_scheduler.c index 651129f2ec1d..3a4820e863ec 100644 --- a/drivers/gpu/drm/amd/scheduler/gpu_scheduler.c +++ b/drivers/gpu/drm/amd/scheduler/gpu_scheduler.c @@ -288,6 +288,7 @@ amd_sched_entity_pop_job(struct amd_sched_entity *entity) */ static bool amd_sched_entity_in(struct amd_sched_job *sched_job) { + struct amd_gpu_scheduler *sched = sched_job->sched; struct amd_sched_entity *entity = sched_job->s_entity; bool added, first = false; @@ -302,7 +303,7 @@ static bool amd_sched_entity_in(struct amd_sched_job *sched_job) /* first job wakes up scheduler */ if (first) - amd_sched_wakeup(sched_job->sched); + amd_sched_wakeup(sched); return added; } @@ -318,9 +319,9 @@ void amd_sched_entity_push_job(struct amd_sched_job *sched_job) { struct amd_sched_entity *entity = sched_job->s_entity; + trace_amd_sched_job(sched_job); wait_event(entity->sched->job_scheduled, amd_sched_entity_in(sched_job)); - trace_amd_sched_job(sched_job); } /**