github-mirror/linux
1
0
Fork 0
mirror of https://github.com/torvalds/linux.git synced 2026-05-25 15:41:52 +02:00
Code Issues Actions Packages Projects Releases Wiki Activity Graph

mptcp: do not drop partial packets

Browse Source 
When a packet arrives with map_seq < ack_seq < end_seq, the beginning
of the packet has already been acknowledged but the end contains new
data. Currently the entire packet is dropped as "old data," forcing
the sender to retransmit.

Instead, skip the already-acked bytes by adjusting the skb offset and
enqueue only the new portion. Update bytes_received and ack_seq to
reflect the new data consumed.

A previous attempt at this fix has been sent by Paolo Abeni [1], but had
issues [2]: it also added a zero-window check and changed rcv_wnd_sent
initialization, which caused test regressions. This version addresses
only the partial packet handling without modifying receive window
accounting.

Fixes: ab174ad8ef ("mptcp: move ooo skbs into msk out of order queue.")
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/c9b426a4e163aa3c4fe8b80c79f1a610f47ae7d8.1763075056.git.pabeni@redhat.com [1]
Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/600 [2]
Signed-off-by: Shardul Bankar <shardul.b@mpiricsoftware.com>
[pabeni@redhat.com: update map]
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20260515-net-mptcp-misc-fixes-7-1-rc4-v2-1-701e96419f2f@kernel.org
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
This commit is contained in:
Shardul Bankar 2026-05-15 06:27:32 +02:00 committed by Paolo Abeni
parent 956aa1ec97
commit 50c2d91c5d
1 changed files with 19 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

24
net/mptcp/protocol.c
View File

@ -397,12 +397,26 @@ 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;
MPTCP_SKB_CB(skb)->map_seq += msk->ack_seq -
MPTCP_SKB_CB(skb)->map_seq;
msk->bytes_received += copy_len;
WRITE_ONCE(msk->ack_seq, msk->ack_seq + copy_len);
skb_set_owner_r(skb, sk);
__skb_queue_tail(&sk->sk_receive_queue, skb);
return true;
}
static void mptcp_stop_rtx_timer(struct sock *sk)