[PATCH] drm/amdgpu/userq: serialize queue map against GPU reset

[Jesse Zhang <Jesse.Zhang@amd.com>]

Creating a user queue can race with a GPU reset. While recovery holds
reset_domain->sem for write, MES is unresponsive, so the ADD_QUEUE from
amdgpu_userq_map_helper() times out (-110) and an otherwise valid queue
create fails:

  amdgpu: MES(0) failed to respond to msg=ADD_QUEUE
  [drm:mes_userq_map [amdgpu]] *ERROR* Failed to map queue in HW, err (-110)
  amdgpu: [drm] *ERROR* ... Failed to map Queue
  amdgpu: [drm] *ERROR* ... Failed to create usermode queue

Take reset_domain->sem for read around the map so it runs only once MES
is back up. This mirrors amdgpu_userq_cleanup() and honors the
userq_mutex -> reset_domain->sem order; the reset path never takes
userq_mutex, so there is no deadlock.

Signed-off-by: Jesse Zhang <Jesse.Zhang@amd.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_userq.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_userq.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_userq.c
index 652599f08990..770635ab5298 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_userq.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_userq.c
@@ -745,7 +745,12 @@ amdgpu_userq_create(struct drm_file *filp, union drm_amdgpu_userq *args)
 	if (!adev->userq_halt_for_enforce_isolation ||
 	    ((queue->queue_type != AMDGPU_HW_IP_GFX) &&
 	     (queue->queue_type != AMDGPU_HW_IP_COMPUTE))) {
+		/* Serialize the map against an in-progress GPU reset (MES is
+		 * unresponsive during recovery), matching amdgpu_userq_cleanup().
+		 */
+		down_read(&adev->reset_domain->sem);
 		r = amdgpu_userq_map_helper(queue);
+		up_read(&adev->reset_domain->sem);
 		if (r) {
 			drm_file_err(uq_mgr->file, "Failed to map Queue\n");
 			trace_amdgpu_userq_create_end(queue, r);
-- 
2.49.0