cancel_delayed_work_sync for work hand_detect_work should not be locked since the amdgpu_userq_hang_detect_work also need the same mutex and when they run together it could be a deadlock.
we do not need to hold the mutex for cancel_delayed_work_sync(&queue->hang_detect_work). With this in place if cancel and worker thread run at same time they will not deadlock. Due to any failures if there is a hand detect and reset that there a deadlock scenarios between cancel and running the main thread. [ 243.118276] task:kworker/9:0 state:D stack:0 pid:73 tgid:73 ppid:2 task_flags:0x4208060 flags:0x00080000 [ 243.118283] Workqueue: events amdgpu_userq_hang_detect_work [amdgpu] [ 243.118636] Call Trace: [ 243.118639] <TASK> [ 243.118644] __schedule+0x581/0x1810 [ 243.118649] ? srso_return_thunk+0x5/0x5f [ 243.118656] ? srso_return_thunk+0x5/0x5f [ 243.118659] ? wake_up_process+0x15/0x20 [ 243.118665] schedule+0x64/0xe0 [ 243.118668] schedule_preempt_disabled+0x15/0x30 [ 243.118671] __mutex_lock+0x346/0x950 [ 243.118677] __mutex_lock_slowpath+0x13/0x20 [ 243.118681] mutex_lock+0x2c/0x40 [ 243.118684] amdgpu_userq_hang_detect_work+0x63/0x90 [amdgpu] [ 243.118888] process_scheduled_works+0x1f0/0x450 [ 243.118894] worker_thread+0x27f/0x370 [ 243.118899] kthread+0x1ed/0x210 [ 243.118903] ? __pfx_worker_thread+0x10/0x10 [ 243.118906] ? srso_return_thunk+0x5/0x5f [ 243.118909] ? __pfx_kthread+0x10/0x10 [ 243.118913] ret_from_fork+0x10f/0x1b0 [ 243.118916] ? __pfx_kthread+0x10/0x10 [ 243.118920] ret_from_fork_asm+0x1a/0x30 Signed-off-by: Sunil Khatri <[email protected]> --- drivers/gpu/drm/amd/amdgpu/amdgpu_userq.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_userq.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_userq.c index 32541f1bde6d..c5875e175918 100644 --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_userq.c +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_userq.c @@ -621,15 +621,22 @@ amdgpu_userq_destroy(struct amdgpu_userq_mgr *uq_mgr, struct amdgpu_usermode_que { struct amdgpu_device *adev = uq_mgr->adev; int r = 0; + bool hang_detect_fence = false; cancel_delayed_work_sync(&uq_mgr->resume_work); mutex_lock(&uq_mgr->userq_mutex); amdgpu_userq_wait_for_last_fence(queue); /* Cancel any pending hang detection work and cleanup */ if (queue->hang_detect_fence) { - cancel_delayed_work_sync(&queue->hang_detect_work); + hang_detect_fence = true; queue->hang_detect_fence = NULL; } + mutex_unlock(&uq_mgr->userq_mutex); + + if (hang_detect_fence) + cancel_delayed_work_sync(&queue->hang_detect_work); + + mutex_lock(&uq_mgr->userq_mutex); r = amdgpu_bo_reserve(queue->db_obj.obj, true); if (!r) { amdgpu_bo_unpin(queue->db_obj.obj); -- 2.34.1
