kernel/git/stable/linux.git/net/mptcp/protocol.c, branch master

mptcp: avoid pruning for OoW data

2026-09-09T20:32:56+00:00

Pruning is expansive and destructive, do it only when we expect to accept the skb triggering the cleanup. Fixes: e468d371180d ("mptcp: implemented OoO queue pruning") Cc: stable@vger.kernel.org Signed-off-by: Paolo Abeni Reviewed-by: Matthieu Baerts (NGI0) Signed-off-by: Matthieu Baerts (NGI0) Link: https://patch.msgid.link/20260908-net-mptcp-misc-fixes-7-3-rc1-v2-15-df1de70348b6@kernel.org Signed-off-by: Jakub Kicinski

mptcp: being below memory limit is a likely() condition

2026-09-09T20:32:56+00:00

The current compiler hint annotation is wrong, due to inverted logic in the previous revision of the relevant code. Fixes: e468d371180d ("mptcp: implemented OoO queue pruning") Cc: stable@vger.kernel.org Signed-off-by: Paolo Abeni Reviewed-by: Matthieu Baerts (NGI0) Signed-off-by: Matthieu Baerts (NGI0) Link: https://patch.msgid.link/20260908-net-mptcp-misc-fixes-7-3-rc1-v2-14-df1de70348b6@kernel.org Signed-off-by: Jakub Kicinski

mptcp: remove unneeded READ_ONCE() annotation

2026-09-09T20:32:55+00:00

The subflow->fully_established flag is always written under the subflow socket lock. Reading such value under the same lock does not require any ONCE annotation. Fixes: 581c8cbfa934 ("mptcp: annotate data-races around subflow->fully_established") Signed-off-by: Paolo Abeni Reviewed-by: Matthieu Baerts (NGI0) Signed-off-by: Matthieu Baerts (NGI0) Link: https://patch.msgid.link/20260908-net-mptcp-misc-fixes-7-3-rc1-v2-10-df1de70348b6@kernel.org Signed-off-by: Jakub Kicinski

mptcp: prevent race between disconnect() and rtx

2026-09-09T20:32:55+00:00

Sashiko noted that the two event can race, leading to inconsistent status. Prevent the race using the synchronous timer stop operation. Cc: stable@vger.kernel.org Fixes: b29fcfb54cd7 ("mptcp: full disconnect implementation") Signed-off-by: Paolo Abeni Reviewed-by: Matthieu Baerts (NGI0) Signed-off-by: Matthieu Baerts (NGI0) Link: https://patch.msgid.link/20260908-net-mptcp-misc-fixes-7-3-rc1-v2-6-df1de70348b6@kernel.org Signed-off-by: Jakub Kicinski

mptcp: do not reschedule the RTX timer for fallback sockets

2026-09-09T20:32:54+00:00

On fallback socket the retrans timer is a quite convoluted no-op, but currently nothing prevents the MPTCP core to keep rescheduling it. Additionally gate RTX timer reset to the msk not being fallen back to TCP yet. To avoid adding multiple tests in fast-path, use a new flags bit for such condition. The RTX enable bit is clear at close time and set before the msk could start retransmitting, with a couple of caveats: - passive sockets inherit the bit from the listener msk; set the bit on such socket to avoid flipping it in the fast-path, even if the listener will obviously never retransmit. - while fastopening (MPTFO), mptcp_sendmsg_fastopen still ends-up calling mptcp_connect via tcp_sendmsg_fastopen -> __inet_stream_connect(ssk->sk_socket), and the first subflow's sk_socket points to the msk one. Fixes: b51f9b80c032 ("mptcp: introduce MPTCP retransmission timer") Cc: stable@vger.kernel.org Signed-off-by: Paolo Abeni Reviewed-by: Matthieu Baerts (NGI0) Signed-off-by: Matthieu Baerts (NGI0) Link: https://patch.msgid.link/20260908-net-mptcp-misc-fixes-7-3-rc1-v2-1-df1de70348b6@kernel.org Signed-off-by: Jakub Kicinski

tcp: use GFP_ATOMIC in tcp_send_active_reset()

2026-08-28T22:35:38+00:00

tcp_send_active_reset() can be called from contexts where gfp_any() (in tcp_disconnect()) or sk->sk_allocation (in __tcp_close() and mptcp_do_fastclose()) evaluates to GFP_KERNEL, which includes __GFP_FS and __GFP_DIRECT_RECLAIM. Allocating with GFP_KERNEL while holding the socket lock (sk_lock) creates a lockdep dependency: sk_lock -> fs_reclaim This causes false-positive lockdep circular locking warnings with storage subsystems (such as nvme-tcp) that acquire socket locks in block I/O paths and invoke tcp_disconnect() or close sockets upon teardown: set->srcu -> sk_lock -> fs_reclaim -> elevator_lock -> set->srcu Active resets are small RST packet headers that should never enter direct reclaim or block while holding socket locks. Use sk_gfp_mask(sk, GFP_ATOMIC | __GFP_NOWARN) inside tcp_send_active_reset() and remove its priority argument. This preserves __GFP_MEMALLOC access for SOCK_MEMALLOC sockets, suppresses allocation failure warnings, and aligns with other control packet allocations (e.g. tcp_send_fin(), __tcp_send_ack(), tcp_xmit_probe_skb()). Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Eric Dumazet Acked-by: Matthieu Baerts (NGI0) Link: https://patch.msgid.link/20260827095936.551524-1-edumazet@google.com Signed-off-by: Jakub Kicinski

mptcp: add per-event MIB counters for MPTCP_RST_EMPTCP resets

2026-08-18T00:25:49+00:00

MPTCP_RST_EMPTCP (reset reason 1) is used as a catch-all for several distinct error conditions across subflow setup, authentication, and data-path validation. The existing MPRstTx/MPRstRx counters only track aggregate reset volume, making it difficult to diagnose which code path is triggering subflow resets in production. Add per-event MIB counters covering each MPTCP_RST_EMPTCP use site that is not already covered by an existing counter, named after the underlying event or condition rather than the reset action: MD5SigReset MD5SIG enabled on listener (incompatible) MPJoinSynAckNoMPJoin SYN/ACK missing MP_JOIN option MPJoinAckNoMPJoin server-side ACK missing MP_JOIN option (fallback path, MPJoin required) MPJoinAckNoCtx server-side ACK with no subflow context MPJoinNoIdFound MP_JOIN with a valid token but no PM local ID DssReset data mapping invalid (also fires on MAPPING_NODSS / EMIDDLEBOX path) MPJoinNotEstablished JOIN attempted on a not-fully-established msk MPJoinNoIdFound covers the second half of the no-msk MP_JOIN reset: the existing MPJoinNoTokenFound (MPTCP_MIB_JOINNOTOKEN) only counts the missing-token case in subflow_token_join_request(), while a JOIN that carries a valid token but for which the path manager returns no local id reaches the same MPTCP_RST_EMPTCP in subflow_check_req() uncounted. The aggregate MPRstTx/MPRstRx counters are unchanged. Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/511 Signed-off-by: Shardul Bankar Reviewed-by: Matthieu Baerts (NGI0) Signed-off-by: Matthieu Baerts (NGI0) Link: https://patch.msgid.link/20260812-net-next-mptcp-misc-feat-7-3-v1-5-1905a818f6cb@kernel.org Signed-off-by: Jakub Kicinski

mptcp: honour configured min/max RTO in retransmit paths

2026-08-18T00:25:49+00:00

The MPTCP-level retransmit timers (DATA_FIN retransmissions and the fallback timeout) used the hard-coded TCP_RTO_MIN / TCP_RTO_MAX constants, ignoring the tcp_rto_min_us and tcp_rto_max_ms sysctls. Make them follow the sysctls instead: seed icsk_rto_min / icsk_rto_max on the MPTCP socket from the per-netns sysctls in __mptcp_init_sock() -- the msk does not go through tcp_init_sock(), so these fields would otherwise stay zero -- and read them directly where the constants were used: - mptcp_set_datafin_timeout(): both the backoff cap computation and the resulting timer_ival. The two sysctls are validated independently, so rto_min > rto_max is a valid configuration; keep a max_t() guard so ilog2() is never called with 0. - __mptcp_set_timeout(): the fallback when no subflow timeout is available. The icsk fields are read directly instead of using the tcp_rto_min()/tcp_rto_max() helpers: the MPTCP socket does not perform routing lookups in these paths, so the rto_min route metric checked by tcp_rto_min() can never apply here. The TCP_RTO_MIN_US / TCP_RTO_MAX_MS socket options are not supported by MPTCP setsockopt() either; this can be revisited if they get supported on MPTCP sockets. The remaining uses of TCP_RTO_MAX in net/mptcp/ctrl.c (default add_addr_timeout) and net/mptcp/subflow.c (MP_FAIL timeout) are intentionally left unchanged: they use the constant as a default duration, not as an RTO bound on a retransmit timer. Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/618 Signed-off-by: Kalpan Jani Reviewed-by: Matthieu Baerts (NGI0) Signed-off-by: Matthieu Baerts (NGI0) Link: https://patch.msgid.link/20260812-net-next-mptcp-misc-feat-7-3-v1-4-1905a818f6cb@kernel.org Signed-off-by: Jakub Kicinski

mptcp: implemented OoO queue pruning

2026-08-12T01:35:38+00:00

When moving incoming skbs in the msk receive queue and the latter is above limits, prune it as needed quite alike what TCP is doing at the subflow level. The main difference relies in the stop condition: since MPTCP does not perform collapsing, it's better off dropping the bare minimum to fit the (newer) incoming packet. Signed-off-by: Paolo Abeni Tested-by: Gang Yan Reviewed-by: Matthieu Baerts (NGI0) Signed-off-by: Matthieu Baerts (NGI0) Link: https://patch.msgid.link/20260807-net-next-mptcp-oooq-pruning-v3-7-dbc1eb853cc3@kernel.org Signed-off-by: Jakub Kicinski

mptcp: avoid code duplication in __mptcp_move_skb()

2026-08-12T01:35:38+00:00

Alike TCP, MPTCP handles in-sequence packets and partially overlapping ones in a very similar way: we can use the same path to handle both, avoiding some code duplication. This will also make the next patch simpler. Signed-off-by: Paolo Abeni Reviewed-by: Matthieu Baerts (NGI0) Signed-off-by: Matthieu Baerts (NGI0) Link: https://patch.msgid.link/20260807-net-next-mptcp-oooq-pruning-v3-6-dbc1eb853cc3@kernel.org Signed-off-by: Jakub Kicinski