Date:   Wed, 8 Mar 2023 15:16:45 +0000
From:   Bobby Eshleman <bobbyeshleman@gmail.com>
To:     Arseniy Krasnov <avkrasnov@sberdevices.ru>
Cc:     Stefan Hajnoczi <stefanha@redhat.com>,
        Stefano Garzarella <sgarzare@redhat.com>,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>,
        Bobby Eshleman <bobby.eshleman@bytedance.com>,
        kvm@vger.kernel.org, virtualization@lists.linux-foundation.org,
        netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
        kernel@sberdevices.ru, oxffffaa@gmail.com
Subject: Re: [PATCH RESEND net v4 3/4] virtio/vsock: don't drop skbuff on
 copy failure
Message-ID: <ZAim3WjwQ24lpjZi@bullseye>
References: <1bfcb7fd-bce3-30cf-8a58-8baa57b7345c@sberdevices.ru>
 <3f8fcfb1-6d5e-93db-f2d6-651e22dba9ce@sberdevices.ru>
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In-Reply-To: <3f8fcfb1-6d5e-93db-f2d6-651e22dba9ce@sberdevices.ru>
Precedence: bulk

On Tue, Mar 14, 2023 at 02:08:20PM +0300, Arseniy Krasnov wrote:
> 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

Acked-by: Bobby Eshleman <bobby.eshleman@bytedance.com>