[PATCH V2] drm/amdgpu: Fix circular locking in userq creation

[Jesse.Zhang]

A circular locking dependency was detected between the global
`adev->userq_mutex` and per-file `userq_mgr->userq_mutex` when
creating user queues. The issue occurs because:

1. `amdgpu_userq_suspend()` and `amdgpu_userq_resume` take `adev->userq_mutex` first, then
   `userq_mgr->userq_mutex`
2. While `amdgpu_userq_create()` takes them in reverse order

This patch resolves the issue by:
1. Moving the `adev->userq_mutex` lock earlier in `amdgpu_userq_create()`
   to cover the `amdgpu_userq_ensure_ev_fence()` call
2. Releasing it after we're done with both queue creation and the
   scheduling halt check

v2: remove unused adev->userq_mutex lock (Prike)

Signed-off-by: Jesse Zhang <Jesse.Zhang at amd.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_userq.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_userq.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_userq.c
index 697dd3cbd114..2ee63b33724d 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_userq.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_userq.c
@@ -531,6 +531,7 @@ amdgpu_userq_create(struct drm_file *filp, union drm_amdgpu_userq *args)
 	 *
 	 * This will also make sure we have a valid eviction fence ready to be used.
 	 */
+	mutex_lock(&adev->userq_mutex);
 	amdgpu_userq_ensure_ev_fence(&fpriv->userq_mgr, &fpriv->evf_mgr);
 
 	uq_funcs = adev->userq_funcs[args->in.ip_type];
@@ -594,7 +595,6 @@ amdgpu_userq_create(struct drm_file *filp, union drm_amdgpu_userq *args)
 	}
 
 	/* don't map the queue if scheduling is halted */
-	mutex_lock(&adev->userq_mutex);
 	if (adev->userq_halt_for_enforce_isolation &&
 	    ((queue->queue_type == AMDGPU_HW_IP_GFX) ||
 	     (queue->queue_type == AMDGPU_HW_IP_COMPUTE)))
@@ -604,7 +604,6 @@ amdgpu_userq_create(struct drm_file *filp, union drm_amdgpu_userq *args)
 	if (!skip_map_queue) {
 		r = amdgpu_userq_map_helper(uq_mgr, queue);
 		if (r) {
-			mutex_unlock(&adev->userq_mutex);
 			drm_file_err(uq_mgr->file, "Failed to map Queue\n");
 			idr_remove(&uq_mgr->userq_idr, qid);
 			amdgpu_userq_fence_driver_free(queue);
@@ -613,13 +612,13 @@ amdgpu_userq_create(struct drm_file *filp, union drm_amdgpu_userq *args)
 			goto unlock;
 		}
 	}
-	mutex_unlock(&adev->userq_mutex);
 
 
 	args->out.queue_id = qid;
 
 unlock:
 	mutex_unlock(&uq_mgr->userq_mutex);
+	mutex_unlock(&adev->userq_mutex);
 
 	return r;
 }
-- 
2.49.0