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Thu, 01 Oct 2026 06:42:24 -0700 (PDT) Received: from leonardi-redhat ([176.206.38.69]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4a01f984d89sm81821335e9.7.2026.10.01.06.42.22 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 01 Oct 2026 06:42:24 -0700 (PDT) Date: Thu, 1 Oct 2026 15:42:21 +0200 From: Luigi Leonardi To: Daehyeon Ko <4ncienth@gmail.com> Cc: Stefan Hajnoczi , Stefano Garzarella , "Michael S . Tsirkin" , Jason Wang , Eugenio =?utf-8?B?UMOpcmV6?= , Xuan Zhuo , "David S . Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , virtualization@lists.linux.dev, kvm@vger.kernel.org, netdev@vger.kernel.org, bpf@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH net] vsock: account only unread bytes in read_skb() Message-ID: References: <20261001121541.2983379-1-4ncienth@gmail.com> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: <20261001121541.2983379-1-4ncienth@gmail.com> Hi, what about using `vsock/virtio` instead of `vsock`? We are changing just the virtio parts of vsock. On Thu, Oct 01, 2026 at 09:15:41PM +0900, Daehyeon Ko wrote: >After a partial stream receive, rx_bytes tracks the unread suffix while >buf_used and peer credit still cover the whole packet. >virtio_transport_read_skb() dequeues that packet but passes pkt_len for >both counters, underflowing rx_bytes. > >On a connected CID_LOCAL stream with an SK_SKB verdict, a 40-byte read >from a 100-byte packet made SIOCINQ report -40, an empty recv return >ELOOP, and poll report the empty socket readable. After verdict detach, >receiving 40 bytes wrapped the counter to zero and hid those queued bytes >until one more byte arrived. The fixed run kept the counter balanced >and exposed all queued data immediately. > >Subtract only skb->len minus the VSOCK offset from rx_bytes. Retain the >full packet length for buf_used and peer credit. > >Fixes: 45ca7e9f0730 ("vsock/virtio: fix `rx_bytes` accounting for stream sockets") >Cc: stable@vger.kernel.org >Assisted-by: LLM >Signed-off-by: Daehyeon Ko <4ncienth@gmail.com> >--- > net/vmw_vsock/virtio_transport_common.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > >diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c >index f225f53ed4bab..1e762a480df49 100644 >--- a/net/vmw_vsock/virtio_transport_common.c >+++ b/net/vmw_vsock/virtio_transport_common.c >@@ -1927,6 +1927,7 @@ int virtio_transport_read_skb(struct vsock_sock *vsk, skb_read_actor_t recv_acto > struct sock *sk = sk_vsock(vsk); > struct virtio_vsock_hdr *hdr; > struct sk_buff *skb; >+ u32 bytes_read; > u32 pkt_len; > int off = 0; > int err; >@@ -1946,7 +1947,8 @@ int virtio_transport_read_skb(struct vsock_sock *vsk, skb_read_actor_t recv_acto > vvs->msg_count--; > > pkt_len = le32_to_cpu(hdr->len); >- virtio_transport_dec_rx_pkt(vvs, pkt_len, pkt_len); maybe it's worth adding a comment? not a strong opinion. >+ bytes_read = skb->len - VIRTIO_VSOCK_SKB_CB(skb)->offset; >+ virtio_transport_dec_rx_pkt(vvs, bytes_read, pkt_len); > spin_unlock_bh(&vvs->rx_lock); > > virtio_transport_send_credit_update(vsk); > >base-commit: e23a64eb244356ee47c0620f0722d51bd88db522 >-- >2.55.0 > code LGTM! Reviewed-by: Luigi Leonardi Thanks, Luigi