[PATCH net v4 3/4] virtio/vsock: don't drop skbuff on copy failure

[Arseniy Krasnov <avkrasnov@sberdevices.ru>]

This returns behaviour of SOCK_STREAM read as before skbuff usage. When
copying to user fails current skbuff won't be dropped, but returned to
sockets's queue. Technically instead of 'skb_dequeue()', 'skb_peek()' is
called and when skbuff becomes empty, it is removed from queue by
'__skb_unlink()'.

Fixes: 71dc9ec9ac7d ("virtio/vsock: replace virtio_vsock_pkt with sk_buff")
Signed-off-by: Arseniy Krasnov <AVKrasnov@sberdevices.ru>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
---
 net/vmw_vsock/virtio_transport_common.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c
index 9a411475e201..6564192e7f20 100644
--- a/net/vmw_vsock/virtio_transport_common.c
+++ b/net/vmw_vsock/virtio_transport_common.c
@@ -364,7 +364,7 @@ virtio_transport_stream_do_dequeue(struct vsock_sock *vsk,
 
 	spin_lock_bh(&vvs->rx_lock);
 	while (total < len && !skb_queue_empty(&vvs->rx_queue)) {
-		skb = __skb_dequeue(&vvs->rx_queue);
+		skb = skb_peek(&vvs->rx_queue);
 
 		bytes = len - total;
 		if (bytes > skb->len)
@@ -388,9 +388,8 @@ virtio_transport_stream_do_dequeue(struct vsock_sock *vsk,
 			u32 pkt_len = le32_to_cpu(virtio_vsock_hdr(skb)->len);
 
 			virtio_transport_dec_rx_pkt(vvs, pkt_len);
+			__skb_unlink(skb, &vvs->rx_queue);
 			consume_skb(skb);
-		} else {
-			__skb_queue_head(&vvs->rx_queue, skb);
 		}
 	}
 
-- 
2.25.1