Commit 3543152f authored by Michal Luczaj's avatar Michal Luczaj Committed by Daniel Borkmann
Browse files

vsock: Update rx_bytes on read_skb() 



Make sure virtio_transport_inc_rx_pkt() and virtio_transport_dec_rx_pkt()
calls are balanced (i.e. virtio_vsock_sock::rx_bytes doesn't lie) after
vsock_transport::read_skb().

While here, also inform the peer that we've freed up space and it has more
credit.

Failing to update rx_bytes after packet is dequeued leads to a warning on
SOCK_STREAM recv():

[  233.396654] rx_queue is empty, but rx_bytes is non-zero
[  233.396702] WARNING: CPU: 11 PID: 40601 at net/vmw_vsock/virtio_transport_common.c:589

Fixes: 634f1a71 ("vsock: support sockmap")
Suggested-by: default avatarStefano Garzarella <sgarzare@redhat.com>
Signed-off-by: default avatarMichal Luczaj <mhal@rbox.co>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Reviewed-by: default avatarStefano Garzarella <sgarzare@redhat.com>
Acked-by: default avatarJohn Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20241013-vsock-fixes-for-redir-v2-2-d6577bbfe742@rbox.co
parent 9c5bd93e

net/vmw_vsock/virtio_transport_common.c

+9 −2
Original line number Diff line number Diff line
@@ -1707,6 +1707,7 @@ int virtio_transport_read_skb(struct vsock_sock *vsk, skb_read_actor_t recv_acto 
{

	struct virtio_vsock_sock *vvs = vsk->trans;

	struct sock *sk = sk_vsock(vsk);

	struct virtio_vsock_hdr *hdr;

	struct sk_buff *skb;

	int off = 0;

	int err;
@@ -1716,10 +1717,16 @@ int virtio_transport_read_skb(struct vsock_sock *vsk, skb_read_actor_t recv_acto 
	 * works for types other than dgrams.

	 */

	skb = __skb_recv_datagram(sk, &vvs->rx_queue, MSG_DONTWAIT, &off, &err);

	if (!skb) {

		spin_unlock_bh(&vvs->rx_lock);



	if (!skb)

		return err;

	}



	hdr = virtio_vsock_hdr(skb);

	virtio_transport_dec_rx_pkt(vvs, le32_to_cpu(hdr->len));

	spin_unlock_bh(&vvs->rx_lock);



	virtio_transport_send_credit_update(vsk);



	return recv_actor(sk, skb);

}