From: Paolo Abeni <pabeni@redhat.com>
To: Shardul Bankar <shardulsb08@gmail.com>,
matttbe@kernel.org, martineau@kernel.org
Cc: geliang@kernel.org, davem@davemloft.net, edumazet@google.com,
kuba@kernel.org, horms@kernel.org, netdev@vger.kernel.org,
mptcp@lists.linux.dev, linux-kernel@vger.kernel.org,
janak@mpiric.us, kalpan.jani@mpiricsoftware.com,
Shardul Bankar <shardul.b@mpiricsoftware.com>
Subject: Re: [PATCH] mptcp: do not drop partial packets
Date: Wed, 22 Apr 2026 15:51:54 +0200 [thread overview]
Message-ID: <fc2ca10a-1fa8-48f8-b140-6c59595fc08b@redhat.com> (raw)
In-Reply-To: <20260422120954.8877-1-shardul.b@mpiricsoftware.com>
On 4/22/26 2:09 PM, Shardul Bankar wrote:
> diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
> index 614c3f583ca0..6858e6e283e3 100644
> --- a/net/mptcp/protocol.c
> +++ b/net/mptcp/protocol.c
> @@ -397,12 +397,27 @@ static bool __mptcp_move_skb(struct sock *sk, struct sk_buff *skb)
> return false;
> }
>
> - /* old data, keep it simple and drop the whole pkt, sender
> - * will retransmit as needed, if needed.
> + /* Completely old data? */
> + if (!after64(MPTCP_SKB_CB(skb)->end_seq, msk->ack_seq)) {
> + MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_DUPDATA);
> + mptcp_drop(sk, skb);
> + return false;
> + }
> +
> + /* Partial packet: map_seq < ack_seq < end_seq.
> + * Skip the already-acked bytes and enqueue the new data.
> */
> - MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_DUPDATA);
> - mptcp_drop(sk, skb);
> - return false;
> + copy_len = MPTCP_SKB_CB(skb)->end_seq - msk->ack_seq;
> + MPTCP_SKB_CB(skb)->offset += msk->ack_seq - MPTCP_SKB_CB(skb)->map_seq;
here MPTCP_SKB_CB(skb)->offset is always != 0 ...
> + msk->bytes_received += copy_len;
> + WRITE_ONCE(msk->ack_seq, msk->ack_seq + copy_len);
> + tail = skb_peek_tail(&sk->sk_receive_queue);
> + if (tail && mptcp_try_coalesce(sk, tail, skb))
... so mptcp_try_coalesce() will always fail.
/P
next prev parent reply other threads:[~2026-04-22 13:52 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-04-22 12:09 [PATCH] mptcp: do not drop partial packets Shardul Bankar
2026-04-22 13:51 ` Paolo Abeni [this message]
2026-04-22 14:40 ` Shardul Bankar
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