Commit b8ef4809 authored by Xuan Zhuo's avatar Xuan Zhuo Committed by Jakub Kicinski
Browse files

virtio_net: separate the logic of checking whether sq is full 



Separate the logic of checking whether sq is full. The subsequent patch
will reuse this func.

Signed-off-by: default avatarXuan Zhuo <xuanzhuo@linux.alibaba.com>
Reviewed-by: default avatarAlexander Duyck <alexanderduyck@fb.com>
Acked-by: default avatarMichael S. Tsirkin <mst@redhat.com>
Acked-by: default avatarJason Wang <jasowang@redhat.com>
Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent 25074a44

drivers/net/virtio_net.c

+36 −24
Original line number Diff line number Diff line
@@ -591,6 +591,41 @@ static bool is_xdp_raw_buffer_queue(struct virtnet_info *vi, int q) 
		return false;

}



static void check_sq_full_and_disable(struct virtnet_info *vi,

				      struct net_device *dev,

				      struct send_queue *sq)

{

	bool use_napi = sq->napi.weight;

	int qnum;



	qnum = sq - vi->sq;



	/* If running out of space, stop queue to avoid getting packets that we

	 * are then unable to transmit.

	 * An alternative would be to force queuing layer to requeue the skb by

	 * returning NETDEV_TX_BUSY. However, NETDEV_TX_BUSY should not be

	 * returned in a normal path of operation: it means that driver is not

	 * maintaining the TX queue stop/start state properly, and causes

	 * the stack to do a non-trivial amount of useless work.

	 * Since most packets only take 1 or 2 ring slots, stopping the queue

	 * early means 16 slots are typically wasted.

	 */

	if (sq->vq->num_free < 2+MAX_SKB_FRAGS) {

		netif_stop_subqueue(dev, qnum);

		if (use_napi) {

			if (unlikely(!virtqueue_enable_cb_delayed(sq->vq)))

				virtqueue_napi_schedule(&sq->napi, sq->vq);

		} else if (unlikely(!virtqueue_enable_cb_delayed(sq->vq))) {

			/* More just got used, free them then recheck. */

			free_old_xmit_skbs(sq, false);

			if (sq->vq->num_free >= 2+MAX_SKB_FRAGS) {

				netif_start_subqueue(dev, qnum);

				virtqueue_disable_cb(sq->vq);

			}

		}

	}

}



static int __virtnet_xdp_xmit_one(struct virtnet_info *vi,

				   struct send_queue *sq,

				   struct xdp_frame *xdpf)
@@ -1989,30 +2024,7 @@ static netdev_tx_t start_xmit(struct sk_buff *skb, struct net_device *dev) 
		nf_reset_ct(skb);

	}



	/* If running out of space, stop queue to avoid getting packets that we

	 * are then unable to transmit.

	 * An alternative would be to force queuing layer to requeue the skb by

	 * returning NETDEV_TX_BUSY. However, NETDEV_TX_BUSY should not be

	 * returned in a normal path of operation: it means that driver is not

	 * maintaining the TX queue stop/start state properly, and causes

	 * the stack to do a non-trivial amount of useless work.

	 * Since most packets only take 1 or 2 ring slots, stopping the queue

	 * early means 16 slots are typically wasted.

	 */

	if (sq->vq->num_free < 2+MAX_SKB_FRAGS) {

		netif_stop_subqueue(dev, qnum);

		if (use_napi) {

			if (unlikely(!virtqueue_enable_cb_delayed(sq->vq)))

				virtqueue_napi_schedule(&sq->napi, sq->vq);

		} else if (unlikely(!virtqueue_enable_cb_delayed(sq->vq))) {

			/* More just got used, free them then recheck. */

			free_old_xmit_skbs(sq, false);

			if (sq->vq->num_free >= 2+MAX_SKB_FRAGS) {

				netif_start_subqueue(dev, qnum);

				virtqueue_disable_cb(sq->vq);

			}

		}

	}

	check_sq_full_and_disable(vi, dev, sq);



	if (kick || netif_xmit_stopped(txq)) {

		if (virtqueue_kick_prepare(sq->vq) && virtqueue_notify(sq->vq)) {