Re: [PATCH net v2 2/3] virtio-net: remove unused delayed refill worker

["Michael S. Tsirkin" <mst@redhat.com>]

On Fri, Jan 02, 2026 at 10:20:22PM +0700, Bui Quang Minh wrote:
> Since we change to retry refilling receive buffer in NAPI poll instead

change->switched

> of delayed worker, remove all unused delayed refill worker code.

unused -> now unused

> 
> Signed-off-by: Bui Quang Minh <minhquangbui99@gmail.com>
> ---
>  drivers/net/virtio_net.c | 86 ----------------------------------------
>  1 file changed, 86 deletions(-)
> 
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index ac514c9383ae..7e77a05b5662 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -441,9 +441,6 @@ struct virtnet_info {
>  	/* Packet virtio header size */
>  	u8 hdr_len;
>  
> -	/* Work struct for delayed refilling if we run low on memory. */
> -	struct delayed_work refill;
> -
>  	/* UDP tunnel support */
>  	bool tx_tnl;
>  
> @@ -451,12 +448,6 @@ struct virtnet_info {
>  
>  	bool rx_tnl_csum;
>  
> -	/* Is delayed refill enabled? */
> -	bool refill_enabled;
> -
> -	/* The lock to synchronize the access to refill_enabled */
> -	spinlock_t refill_lock;
> -
>  	/* Work struct for config space updates */
>  	struct work_struct config_work;
>  
> @@ -720,20 +711,6 @@ static void virtnet_rq_free_buf(struct virtnet_info *vi,
>  		put_page(virt_to_head_page(buf));
>  }
>  
> -static void enable_delayed_refill(struct virtnet_info *vi)
> -{
> -	spin_lock_bh(&vi->refill_lock);
> -	vi->refill_enabled = true;
> -	spin_unlock_bh(&vi->refill_lock);
> -}
> -
> -static void disable_delayed_refill(struct virtnet_info *vi)
> -{
> -	spin_lock_bh(&vi->refill_lock);
> -	vi->refill_enabled = false;
> -	spin_unlock_bh(&vi->refill_lock);
> -}
> -
>  static void enable_rx_mode_work(struct virtnet_info *vi)
>  {
>  	rtnl_lock();
> @@ -2948,42 +2925,6 @@ static void virtnet_napi_disable(struct receive_queue *rq)
>  	napi_disable(napi);
>  }
>  
> -static void refill_work(struct work_struct *work)
> -{
> -	struct virtnet_info *vi =
> -		container_of(work, struct virtnet_info, refill.work);
> -	bool still_empty;
> -	int i;
> -
> -	for (i = 0; i < vi->curr_queue_pairs; i++) {
> -		struct receive_queue *rq = &vi->rq[i];
> -
> -		/*
> -		 * When queue API support is added in the future and the call
> -		 * below becomes napi_disable_locked, this driver will need to
> -		 * be refactored.
> -		 *
> -		 * One possible solution would be to:
> -		 *   - cancel refill_work with cancel_delayed_work (note:
> -		 *     non-sync)
> -		 *   - cancel refill_work with cancel_delayed_work_sync in
> -		 *     virtnet_remove after the netdev is unregistered
> -		 *   - wrap all of the work in a lock (perhaps the netdev
> -		 *     instance lock)
> -		 *   - check netif_running() and return early to avoid a race
> -		 */
> -		napi_disable(&rq->napi);
> -		still_empty = !try_fill_recv(vi, rq, GFP_KERNEL);
> -		virtnet_napi_do_enable(rq->vq, &rq->napi);
> -
> -		/* In theory, this can happen: if we don't get any buffers in
> -		 * we will *never* try to fill again.
> -		 */
> -		if (still_empty)
> -			schedule_delayed_work(&vi->refill, HZ/2);
> -	}
> -}
> -
>  static int virtnet_receive_xsk_bufs(struct virtnet_info *vi,
>  				    struct receive_queue *rq,
>  				    int budget,
> @@ -3222,8 +3163,6 @@ static int virtnet_open(struct net_device *dev)
>  	struct virtnet_info *vi = netdev_priv(dev);
>  	int i, err;
>  
> -	enable_delayed_refill(vi);
> -
>  	for (i = 0; i < vi->max_queue_pairs; i++) {
>  		if (i < vi->curr_queue_pairs)
>  			/* If this fails, we will retry later in
> @@ -3249,9 +3188,6 @@ static int virtnet_open(struct net_device *dev)
>  	return 0;
>  
>  err_enable_qp:
> -	disable_delayed_refill(vi);
> -	cancel_delayed_work_sync(&vi->refill);
> -
>  	for (i--; i >= 0; i--) {
>  		virtnet_disable_queue_pair(vi, i);
>  		virtnet_cancel_dim(vi, &vi->rq[i].dim);
> @@ -3445,24 +3381,12 @@ static void virtnet_rx_pause_all(struct virtnet_info *vi)
>  {
>  	int i;
>  
> -	/*
> -	 * Make sure refill_work does not run concurrently to
> -	 * avoid napi_disable race which leads to deadlock.
> -	 */
> -	disable_delayed_refill(vi);
> -	cancel_delayed_work_sync(&vi->refill);
>  	for (i = 0; i < vi->max_queue_pairs; i++)
>  		__virtnet_rx_pause(vi, &vi->rq[i]);
>  }
>  
>  static void virtnet_rx_pause(struct virtnet_info *vi, struct receive_queue *rq)
>  {
> -	/*
> -	 * Make sure refill_work does not run concurrently to
> -	 * avoid napi_disable race which leads to deadlock.
> -	 */
> -	disable_delayed_refill(vi);
> -	cancel_delayed_work_sync(&vi->refill);
>  	__virtnet_rx_pause(vi, rq);
>  }
>  
> @@ -3486,7 +3410,6 @@ static void virtnet_rx_resume_all(struct virtnet_info *vi)
>  {
>  	int i;
>  
> -	enable_delayed_refill(vi);
>  	for (i = 0; i < vi->max_queue_pairs; i++) {
>  		if (i < vi->curr_queue_pairs)
>  			__virtnet_rx_resume(vi, &vi->rq[i], true);
> @@ -3497,7 +3420,6 @@ static void virtnet_rx_resume_all(struct virtnet_info *vi)
>  
>  static void virtnet_rx_resume(struct virtnet_info *vi, struct receive_queue *rq)
>  {
> -	enable_delayed_refill(vi);
>  	__virtnet_rx_resume(vi, rq, true);
>  }
>  
> @@ -3848,10 +3770,6 @@ static int virtnet_close(struct net_device *dev)
>  	struct virtnet_info *vi = netdev_priv(dev);
>  	int i;
>  
> -	/* Make sure NAPI doesn't schedule refill work */
> -	disable_delayed_refill(vi);
> -	/* Make sure refill_work doesn't re-enable napi! */
> -	cancel_delayed_work_sync(&vi->refill);
>  	/* Prevent the config change callback from changing carrier
>  	 * after close
>  	 */
> @@ -5807,7 +5725,6 @@ static int virtnet_restore_up(struct virtio_device *vdev)
>  
>  	virtio_device_ready(vdev);
>  
> -	enable_delayed_refill(vi);
>  	enable_rx_mode_work(vi);
>  
>  	if (netif_running(vi->dev)) {
> @@ -6564,7 +6481,6 @@ static int virtnet_alloc_queues(struct virtnet_info *vi)
>  	if (!vi->rq)
>  		goto err_rq;
>  
> -	INIT_DELAYED_WORK(&vi->refill, refill_work);
>  	for (i = 0; i < vi->max_queue_pairs; i++) {
>  		vi->rq[i].pages = NULL;
>  		netif_napi_add_config(vi->dev, &vi->rq[i].napi, virtnet_poll,
> @@ -6906,7 +6822,6 @@ static int virtnet_probe(struct virtio_device *vdev)
>  
>  	INIT_WORK(&vi->config_work, virtnet_config_changed_work);
>  	INIT_WORK(&vi->rx_mode_work, virtnet_rx_mode_work);
> -	spin_lock_init(&vi->refill_lock);
>  
>  	if (virtio_has_feature(vdev, VIRTIO_NET_F_MRG_RXBUF)) {
>  		vi->mergeable_rx_bufs = true;
> @@ -7170,7 +7085,6 @@ static int virtnet_probe(struct virtio_device *vdev)
>  	net_failover_destroy(vi->failover);
>  free_vqs:
>  	virtio_reset_device(vdev);
> -	cancel_delayed_work_sync(&vi->refill);
>  	free_receive_page_frags(vi);
>  	virtnet_del_vqs(vi);
>  free:
> -- 
> 2.43.0