On Wed, Jun 10, 2026 at 10:17 AM Menglong Dong <[email protected]> wrote: > > For now, XDP_RING_NEED_WAKEUP is not supported properly by the virtio-net. > Take the tx path for example, we set xsk_set_tx_need_wakeup() in > virtnet_xsk_xmit(), but we didn't call xsk_clear_tx_need_wakeup() > anywhere, which means the user will call send() for every packet. > > For the tx path, we will call xsk_set_tx_need_wakeup() after > virtnet_xsk_xmit_batch() if sq->vq is empty, as we can't be wakeup by the > skb_xmit_done() in this case. Otherwise, we will clear the wakeup flag. > > For the rx path, we will call xsk_set_rx_need_wakeup() if we have free > buffers in rq->vq. > > Race condition is considered for both rx and tx path. >
I didn't review the code itself, but the patch message lacks a Fixes: tag. And the From and Signed-off-by emails don't match, which I'm not sure is valid. > Signed-off-by: Menglong Dong <[email protected]> > --- > drivers/net/virtio_net.c | 52 ++++++++++++++++++++++++++++++++++------ > 1 file changed, 45 insertions(+), 7 deletions(-) > > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c > index 9b3da9f9786c..25e895b849a6 100644 > --- a/drivers/net/virtio_net.c > +++ b/drivers/net/virtio_net.c > @@ -1323,16 +1323,27 @@ static int virtnet_add_recvbuf_xsk(struct > virtnet_info *vi, struct receive_queue > struct xsk_buff_pool *pool, gfp_t gfp) > { > struct xdp_buff **xsk_buffs; > + bool need_wakeup; > dma_addr_t addr; > int err = 0; > u32 len, i; > int num; > > + need_wakeup = xsk_uses_need_wakeup(pool); > xsk_buffs = rq->xsk_buffs; > > + /* If both rq->vq and fill ring are empty, and then the user submit > + * all the chunks to the fill ring and check the wake up flag > + * after xsk_buff_alloc_batch() and before xsk_set_rx_need_wakeup(), > + * we will lose the chance to wake up the rx napi, so we have to > + * set the need_wakeup flag here. > + */ > + if (need_wakeup && virtqueue_get_vring_size(rq->vq) == > rq->vq->num_free) > + xsk_set_rx_need_wakeup(pool); > + > num = xsk_buff_alloc_batch(pool, xsk_buffs, rq->vq->num_free); > if (!num) { > - if (xsk_uses_need_wakeup(pool)) { > + if (need_wakeup) { > xsk_set_rx_need_wakeup(pool); > /* Return 0 instead of -ENOMEM so that NAPI is > * descheduled. > @@ -1341,8 +1352,6 @@ static int virtnet_add_recvbuf_xsk(struct virtnet_info > *vi, struct receive_queue > } > > return -ENOMEM; > - } else { > - xsk_clear_rx_need_wakeup(pool); > } > > len = xsk_pool_get_rx_frame_size(pool) + vi->hdr_len; > @@ -1363,6 +1372,16 @@ static int virtnet_add_recvbuf_xsk(struct virtnet_info > *vi, struct receive_queue > goto err; > } > > + if (need_wakeup) { > + if (rq->vq->num_free) > + /* We have free buffers, so we'd better wake up the > + * rx napi as soon as possible. > + */ > + xsk_set_rx_need_wakeup(pool); > + else > + xsk_clear_rx_need_wakeup(pool); > + } > + > return num; > > err: > @@ -1440,8 +1459,9 @@ static bool virtnet_xsk_xmit(struct send_queue *sq, > struct xsk_buff_pool *pool, > struct virtnet_info *vi = sq->vq->vdev->priv; > struct virtnet_sq_free_stats stats = {}; > struct net_device *dev = vi->dev; > + int sent, vring_size; > + bool need_wakeup; > u64 kicks = 0; > - int sent; > > /* Avoid to wakeup napi meanless, so call __free_old_xmit instead of > * free_old_xmit(). > @@ -1451,8 +1471,29 @@ static bool virtnet_xsk_xmit(struct send_queue *sq, > struct xsk_buff_pool *pool, > if (stats.xsk) > xsk_tx_completed(sq->xsk_pool, stats.xsk); > > + vring_size = virtqueue_get_vring_size(sq->vq); > + need_wakeup = xsk_uses_need_wakeup(pool); > + /* If the sq->vq is empty, and the tx ring is empty, and the user > + * submit an entry to the tx ring after virtnet_xsk_xmit_batch() and > + * before xsk_set_tx_need_wakeup(), we will lose the chance to wake > + * up the tx napi, so we have to set the need_wakeup flag here. > + */ > + if (need_wakeup && vring_size == sq->vq->num_free) > + xsk_set_tx_need_wakeup(pool); > + > sent = virtnet_xsk_xmit_batch(sq, pool, budget, &kicks); > > + if (need_wakeup) { > + if (vring_size == sq->vq->num_free) > + /* we can't wake up by ourself, and it should be done > + * by the user. > + */ > + xsk_set_tx_need_wakeup(pool); > + else > + /* we can wake up from skb_xmit_done() */ > + xsk_clear_tx_need_wakeup(pool); > + } > + > if (!is_xdp_raw_buffer_queue(vi, sq - vi->sq)) > check_sq_full_and_disable(vi, vi->dev, sq); > > @@ -1470,9 +1511,6 @@ static bool virtnet_xsk_xmit(struct send_queue *sq, > struct xsk_buff_pool *pool, > u64_stats_add(&sq->stats.xdp_tx, sent); > u64_stats_update_end(&sq->stats.syncp); > > - if (xsk_uses_need_wakeup(pool)) > - xsk_set_tx_need_wakeup(pool); > - > return sent; > } > > -- > 2.54.0 >
