Re: [PATCH v2 2/2] drm/amdgpu: Add CHANGE_ID option for USERQ ioctl

On 11/08/2026 15:12, David Francis wrote:
> Add a new option to the USERQ ioctl, which is called with
> the queue_id of an existing user queue and an unused queue_id,
> and changes that queue's id to the new value.
> 
> Calling with an invalid new handle will fail. Calling with new_handle
> =handle will succeed if that queue exists but not do anything.
> 
> This operation holds userq_mutex and the userq_xa xa_lock for its
> entire duration.
> 
> Performing this operation on a queue with signals or waits
> outstanding is fine, as those hold not the queue_id but a
> direct reference to the queue object.
> 
> Signed-off-by: David Francis <[email protected]>
> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu_userq.c | 43 +++++++++++++++++++++++
>   include/uapi/drm/amdgpu_drm.h             | 17 +++++++--
>   2 files changed, 57 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_userq.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_userq.c
> index 3c930425c1bb..b532ba0f4cef 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_userq.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_userq.c
> @@ -852,6 +852,11 @@ static int amdgpu_userq_input_args_validate(struct drm_device *dev,
>   		break;
>   	case AMDGPU_USERQ_OP_LIST:
>   		break;
> +	case AMDGPU_USERQ_OP_CHANGE_ID:
> +		if (!args->change_in.new_queue_id ||
> +		    args->change_in.new_queue_id > AMDGPU_MAX_USERQ_COUNT)
> +			return -EINVAL;
> +		break;
>   	default:
>   		return -EINVAL;
>   	}
> @@ -1012,6 +1017,41 @@ amdgpu_userq_list(struct drm_file *filp, union drm_amdgpu_userq *args)
>   	return ret;
>   }
>   
> +static int amdgpu_userq_change_id(struct drm_file *filp, union drm_amdgpu_userq *args)
> +{
> +	struct amdgpu_fpriv *fpriv = filp->driver_priv;
> +	struct amdgpu_userq_mgr *uq_mgr = &fpriv->userq_mgr;
> +	struct amdgpu_usermode_queue *queue;
> +	int ret = 0;
> +
> +	mutex_lock(&uq_mgr->userq_mutex);
> +	xa_lock(&uq_mgr->userq_xa);
> +
> +	queue = xa_load(&uq_mgr->userq_xa, args->change_in.queue_id);
> +	if (!queue) {
> +		ret = -ENOENT;
> +		goto unlock;
> +	}
> +
> +	if (args->change_in.new_queue_id == args->change_in.queue_id) {

I would move this outside the lock or even consider returning -EINVAL. 
Or you have a reason why returning success is handy? Probing what 
exists? Why?

> +		ret = 0;
> +		goto unlock;
> +	}
> +
> +	ret = __xa_insert(&uq_mgr->userq_xa, args->change_in.new_queue_id, queue, GFP_KERNEL);

Same as for the list ioctl, GFP_KERNEL under the xa_lock will not work.

You can have a look on how I've done it in "drm/amdgpu: Add context 
handle renaming operation" and see if you can punch some holes in my 
logic there?

If that works question will be do you really need both the userq_mutext 
and xa_lock or perhaps xa_lock would be enough throughout the series.

Regards,

Tvrtko

> +	if (ret) {
> +		ret = -EINVAL;
> +		goto unlock;
> +	}
> +
> +	__xa_erase(&uq_mgr->userq_xa, args->change_in.queue_id);
> +
> +unlock:
> +	xa_unlock(&uq_mgr->userq_xa);
> +	mutex_unlock(&uq_mgr->userq_mutex);
> +	return ret;
> +}
> +
>   bool amdgpu_userq_enabled(struct drm_device *dev)
>   {
>   	struct amdgpu_device *adev = drm_to_adev(dev);
> @@ -1058,6 +1098,9 @@ int amdgpu_userq_ioctl(struct drm_device *dev, void *data,
>   	case AMDGPU_USERQ_OP_LIST:
>   		r = amdgpu_userq_list(filp, args);
>   		break;
> +	case AMDGPU_USERQ_OP_CHANGE_ID:
> +		r = amdgpu_userq_change_id(filp, args);
> +		break;
>   	default:
>   		drm_dbg_driver(dev, "Invalid user queue op specified: %d\n", args->in.op);
>   		return -EINVAL;
> diff --git a/include/uapi/drm/amdgpu_drm.h b/include/uapi/drm/amdgpu_drm.h
> index 678f3d531df7..de9ae1296819 100644
> --- a/include/uapi/drm/amdgpu_drm.h
> +++ b/include/uapi/drm/amdgpu_drm.h
> @@ -330,9 +330,10 @@ union drm_amdgpu_ctx {
>   };
>   
>   /* user queue IOCTL operations */
> -#define AMDGPU_USERQ_OP_CREATE	1
> -#define AMDGPU_USERQ_OP_FREE	2
> -#define AMDGPU_USERQ_OP_LIST	3
> +#define AMDGPU_USERQ_OP_CREATE		1
> +#define AMDGPU_USERQ_OP_FREE		2
> +#define AMDGPU_USERQ_OP_LIST		3
> +#define AMDGPU_USERQ_OP_CHANGE_ID	4
>   
>   /* queue priority levels */
>   /* low < normal low < normal high < high */
> @@ -463,10 +464,20 @@ struct drm_amdgpu_userq_list_in_out {
>   	__u64   entries;
>   };
>   
> +struct drm_amdgpu_userq_change_id_in {
> +	/** AMDGPU_USERQ_OP_CHANGE_ID */
> +	__u32   op;
> +	/** Queue id of some queue */
> +	__u32   queue_id;
> +	/** Queue id to change that queue to */
> +	__u32   new_queue_id;
> +};
> +
>   union drm_amdgpu_userq {
>   	struct drm_amdgpu_userq_in in;
>   	struct drm_amdgpu_userq_out out;
>   	struct drm_amdgpu_userq_list_in_out list_in_out;
> +	struct drm_amdgpu_userq_change_id_in change_in;
>   };
>   
>   /* GFX V11 IP specific MQD parameters */