This series lets MPTCP applications use poll(EPOLLERR) and recvmsg(MSG_ERRQUEUE) on the MPTCP socket to drain TX timestamps through the standard inet ABI, the same way they would on a plain TCP socket. ICMP-derived errors stay on the subflow queue: the legacy RECVERR ABI cannot convey their per-subflow peer identity, and they are intended for a future MPTCP_RECERR channel.
- Patch 1 splices subflow err-skbs onto the MPTCP's sk_error_queue at error-report time. All forwarded events go through sock_queue_err_skb, which re-homes skb->sk onto the MPTCP and charges sk_rmem_alloc, so the MPTCP's error queue stays bounded by sk_rcvbuf and is dropped under rmem pressure, matching tcp's tx-timestamp path and ip_icmp_error() / ipv6_icmp_error(). mptcp_recvmsg(MSG_ERRQUEUE) forwards directly to inet_recv_error(), and mptcp_poll() advertises EPOLLERR purely on the MPTCP's sk_err / sk_error_queue, matching tcp_poll(). - Patch 2 factors the existing inet_flags subflow-propagation hard-coded list into a mask, so the next patch can extend it without churn. - Patch 3 makes IP_RECVERR / IPV6_RECVERR (and the RFC4884 variants) propagate to the subflows. The MPTCP stores the bit so MPTCP-aware helpers can branch on it. - Patch 4 is a selftest covering the propagation path. Signed-off-by: Matthieu Baerts (NGI0) <[email protected]> --- David Carlier (4): mptcp: support MSG_ERRQUEUE on the parent socket mptcp: sockopt: factor inet_flags propagation into a mask mptcp: propagate RECVERR sockopts to subflows selftests: mptcp: cover IP_RECVERR sockopt propagation net/mptcp/protocol.c | 55 ++++++-- net/mptcp/sockopt.c | 155 ++++++++++++++++++---- tools/testing/selftests/net/mptcp/mptcp_sockopt.c | 70 ++++++++++ 3 files changed, 246 insertions(+), 34 deletions(-) --- base-commit: 4bb9710c6a68d35207f123aef55dcd50e7195ec5 change-id: 20260918-net-next-mptcp-msg_errqueue-0e2049a30061 Best regards, -- Matthieu Baerts (NGI0) <[email protected]>
