Addressing comments reported by Clashiko [1], but not detected before
with the AI review tools using a different model version.
Note: the last comment from the 3rd patch has not been addressed, as it
is not clear to me whether this comment is valid:
---------------------------------- 8< ----------------------------------
> diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
> index 72b1fa3ca71c..5f7d8340a3d9 100644
> --- a/net/mptcp/protocol.c
> +++ b/net/mptcp/protocol.c
[ ... ]
> @@ -682,6 +693,16 @@ static void __mptcp_add_backlog(struct sock *sk,
> return;
> }
>
> + /* Similar additional allowance as plain TCP. */
> + limit = READ_ONCE(sk->sk_rcvbuf);
> + limit += (limit >> 1) + 64 * 1024;
> + limit = min_t(u64, limit, UINT_MAX);
> + if (msk->backlog_len > limit && !__mptcp_check_fallback(msk)) {
> + __MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_BACKLOGDROP);
> + kfree_skb_reason(skb, SKB_DROP_REASON_SOCKET_BACKLOG);
> + return;
> + }
> +
[Low]
The check compares the current backlog_len against limit before the
incoming skb's truesize is added (the truesize is folded in at the
account: label further down). Was that intentional?
TCP's sk_add_backlog() analog compares queue_size + skb->truesize
against the limit, so a single skb can push msk->backlog_len past
limit here and the drop only fires on the next admission. The overshoot
is bounded by one skb's truesize and the commit message already notes
"This is not a complete fix for the stall issue, as the drop strategy
needs refinements that will come in the next patches.", so perhaps this
is one of the follow-up items?
---------------------------------- 8< ----------------------------------
Link: https://netdev-ai.bots.linux.dev/sashiko/#/patchset/20260724-net-next-mptcp-oooq-pruning-v1-0-5dd4dec63a54%40kernel.org
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
---
Matthieu Baerts (NGI0) (2):
Squash to "mptcp: explicitly drop over memory limits"
Squash to "mptcp: implemented OoO queue pruning"
net/mptcp/mib.c | 2 +-
net/mptcp/mib.h | 4 ++--
net/mptcp/options.c | 6 +++++-
net/mptcp/protocol.c | 2 +-
4 files changed, 9 insertions(+), 5 deletions(-)
---
base-commit: 23c7cb4262d954b810468b0e661d48af82b418d5
change-id: 20260730-mptcp-squash-ooo-pruning-53d668d4c2aa
Best regards,
--
Matthieu Baerts (NGI0) <matttbe@kernel.org>