Re: [PATCH v2 1/2] drm/amdgpu/userq: avoid uneccessary locking in amdgpu_userq_create

["Christian König" <christian.koenig@amd.com>]

On 4/8/26 11:38, Sunil Khatri wrote:
> Reorganise code to avoid holding mutex userq_mutex while
> also trying to grab exec lock ww_mutex where its not needed
> for function amdgpu_userq_input_va_validate
> 
> Signed-off-by: Sunil Khatri <sunil.khatri@amd.com>

Reviewed-by: Christian König <christian.koenig@amd.com>

> ---
>  drivers/gpu/drm/amd/amdgpu/amdgpu_userq.c | 28 ++++++++++-------------
>  1 file changed, 12 insertions(+), 16 deletions(-)
> 
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_userq.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_userq.c
> index 3a6e7a569c78..c19d993fe8c3 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_userq.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_userq.c
> @@ -737,28 +737,17 @@ amdgpu_userq_create(struct drm_file *filp, union drm_amdgpu_userq *args)
>  		return r;
>  	}
>  
> -	/*
> -	 * There could be a situation that we are creating a new queue while
> -	 * the other queues under this UQ_mgr are suspended. So if there is any
> -	 * resume work pending, wait for it to get done.
> -	 *
> -	 * This will also make sure we have a valid eviction fence ready to be used.
> -	 */
> -	amdgpu_userq_ensure_ev_fence(&fpriv->userq_mgr, &fpriv->evf_mgr);
> -
>  	uq_funcs = adev->userq_funcs[args->in.ip_type];
>  	if (!uq_funcs) {
>  		drm_file_err(uq_mgr->file, "Usermode queue is not supported for this IP (%u)\n",
>  			     args->in.ip_type);
> -		r = -EINVAL;
> -		goto unlock;
> +		return -EINVAL;
>  	}
>  
>  	queue = kzalloc(sizeof(struct amdgpu_usermode_queue), GFP_KERNEL);
>  	if (!queue) {
>  		drm_file_err(uq_mgr->file, "Failed to allocate memory for queue\n");
> -		r = -ENOMEM;
> -		goto unlock;
> +		return -ENOMEM;
>  	}
>  
>  	INIT_LIST_HEAD(&queue->userq_va_list);
> @@ -797,6 +786,15 @@ amdgpu_userq_create(struct drm_file *filp, union drm_amdgpu_userq *args)
>  		goto free_queue;
>  	}
>  
> +	/*
> +	 * There could be a situation that we are creating a new queue while
> +	 * the other queues under this UQ_mgr are suspended. So if there is any
> +	 * resume work pending, wait for it to get done.
> +	 *
> +	 * This will also make sure we have a valid eviction fence ready to be used.
> +	 */
> +	amdgpu_userq_ensure_ev_fence(&fpriv->userq_mgr, &fpriv->evf_mgr);
> +
>  	r = uq_funcs->mqd_create(queue, &args->in);
>  	if (r) {
>  		drm_file_err(uq_mgr->file, "Failed to create Queue\n");
> @@ -858,11 +856,9 @@ amdgpu_userq_create(struct drm_file *filp, union drm_amdgpu_userq *args)
>  	up_read(&adev->reset_domain->sem);
>  clean_fence_driver:
>  	amdgpu_userq_fence_driver_free(queue);
> +	mutex_unlock(&uq_mgr->userq_mutex);
>  free_queue:
>  	kfree(queue);
> -unlock:
> -	mutex_unlock(&uq_mgr->userq_mutex);
> -
>  	return r;
>  }
>