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Message-ID: <20260103040903-mutt-send-email-mst@kernel.org>
Date: Sat, 3 Jan 2026 04:09:45 -0500
From: "Michael S. Tsirkin" <mst@...hat.com>
To: Bui Quang Minh <minhquangbui99@...il.com>
Cc: netdev@...r.kernel.org, Jason Wang <jasowang@...hat.com>,
Xuan Zhuo <xuanzhuo@...ux.alibaba.com>,
Eugenio Pérez <eperezma@...hat.com>,
Andrew Lunn <andrew+netdev@...n.ch>,
"David S. Miller" <davem@...emloft.net>,
Eric Dumazet <edumazet@...gle.com>,
Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
Alexei Starovoitov <ast@...nel.org>,
Daniel Borkmann <daniel@...earbox.net>,
Jesper Dangaard Brouer <hawk@...nel.org>,
John Fastabend <john.fastabend@...il.com>,
Stanislav Fomichev <sdf@...ichev.me>,
virtualization@...ts.linux.dev, linux-kernel@...r.kernel.org,
bpf@...r.kernel.org
Subject: Re: [PATCH net v2 2/3] virtio-net: remove unused delayed refill
worker
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@...il.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
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