Re: [PATCH net-next] virtio-net: xsk: Support wakeup on RX side

[Bui Quang Minh <minhquangbui99@gmail.com>]

Hi Jason,

On 2/28/26 10:49, Jason Xing wrote:
> Hi Bui,
>
> On Fri, Feb 27, 2026 at 11:20 PM Bui Quang Minh
> <minhquangbui99@gmail.com> wrote:
>> When XDP_USE_NEED_WAKEUP is used and the fill ring is empty so no buffer
>> is allocated on RX side, allow RX NAPI to be descheduled. This avoids
>> wasting CPU cycles on polling. Users will be notified and they need to
>> make a wakeup call after refilling the ring.
>>
>> Signed-off-by: Bui Quang Minh <minhquangbui99@gmail.com>
>> ---
>>   drivers/net/virtio_net.c | 38 ++++++++++++++++++++++++++++++--------
>>   1 file changed, 30 insertions(+), 8 deletions(-)
>>
>> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
>> index db88dcaefb20..494acc904b2c 100644
>> --- a/drivers/net/virtio_net.c
>> +++ b/drivers/net/virtio_net.c
>> @@ -1454,8 +1454,19 @@ static int virtnet_add_recvbuf_xsk(struct virtnet_info *vi, struct receive_queue
>>          xsk_buffs = rq->xsk_buffs;
>>
>>          num = xsk_buff_alloc_batch(pool, xsk_buffs, rq->vq->num_free);
>> -       if (!num)
>> +       if (!num) {
>> +               if (xsk_uses_need_wakeup(pool)) {
>> +                       xsk_set_rx_need_wakeup(pool);
>> +                       /* Return 0 instead of -ENOMEM so that NAPI is
>> +                        * descheduled.
>> +                        */
>> +                       return 0;
>> +               }
>> +
>>                  return -ENOMEM;
>> +       } else {
>> +               xsk_clear_rx_need_wakeup(pool);
>> +       }
>>
>>          len = xsk_pool_get_rx_frame_size(pool) + vi->hdr_len;
>>
>> @@ -1588,20 +1599,21 @@ static bool virtnet_xsk_xmit(struct send_queue *sq, struct xsk_buff_pool *pool,
>>          return sent;
>>   }
>>
>> -static void xsk_wakeup(struct send_queue *sq)
>> +static void xsk_wakeup(struct napi_struct *napi, struct virtqueue *vq)
>>   {
>> -       if (napi_if_scheduled_mark_missed(&sq->napi))
>> +       if (napi_if_scheduled_mark_missed(napi))
>>                  return;
>>
>>          local_bh_disable();
>> -       virtqueue_napi_schedule(&sq->napi, sq->vq);
>> +       virtqueue_napi_schedule(napi, vq);
>>          local_bh_enable();
>>   }
>>
>>   static int virtnet_xsk_wakeup(struct net_device *dev, u32 qid, u32 flag)
>>   {
>>          struct virtnet_info *vi = netdev_priv(dev);
>> -       struct send_queue *sq;
>> +       struct napi_struct *napi;
>> +       struct virtqueue *vq;
>>
>>          if (!netif_running(dev))
>>                  return -ENETDOWN;
>> @@ -1609,9 +1621,19 @@ static int virtnet_xsk_wakeup(struct net_device *dev, u32 qid, u32 flag)
>>          if (qid >= vi->curr_queue_pairs)
>>                  return -EINVAL;
>>
>> -       sq = &vi->sq[qid];
>> +       if (flag == XDP_WAKEUP_TX) {
> Better use &?

Sorry, I don't get your point. Can you elaborate more?

Thanks,
Quang Minh.