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4 daysmptcp: avoid pruning for OoW dataPaolo Abeni
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 <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/20260908-net-mptcp-misc-fixes-7-3-rc1-v2-15-df1de70348b6@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
4 daysmptcp: being below memory limit is a likely() conditionPaolo Abeni
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 <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/20260908-net-mptcp-misc-fixes-7-3-rc1-v2-14-df1de70348b6@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
4 daysmptcp: remove unneeded READ_ONCE() annotationPaolo Abeni
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 <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/20260908-net-mptcp-misc-fixes-7-3-rc1-v2-10-df1de70348b6@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
4 daysmptcp: prevent race between disconnect() and rtxPaolo Abeni
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 <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/20260908-net-mptcp-misc-fixes-7-3-rc1-v2-6-df1de70348b6@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
4 daysmptcp: do not reschedule the RTX timer for fallback socketsPaolo Abeni
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 <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/20260908-net-mptcp-misc-fixes-7-3-rc1-v2-1-df1de70348b6@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-08-28tcp: use GFP_ATOMIC in tcp_send_active_reset()Eric Dumazet
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 <edumazet@google.com> Acked-by: Matthieu Baerts (NGI0) <matttbe@kernel.org> Link: https://patch.msgid.link/20260827095936.551524-1-edumazet@google.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-08-17mptcp: add per-event MIB counters for MPTCP_RST_EMPTCP resetsShardul Bankar
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 <shardul.b@mpiricsoftware.com> Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org> Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org> Link: https://patch.msgid.link/20260812-net-next-mptcp-misc-feat-7-3-v1-5-1905a818f6cb@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-08-17mptcp: honour configured min/max RTO in retransmit pathsKalpan Jani
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 <kalpan.jani@mpiricsoftware.com> Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org> Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org> Link: https://patch.msgid.link/20260812-net-next-mptcp-misc-feat-7-3-v1-4-1905a818f6cb@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-08-11mptcp: implemented OoO queue pruningPaolo Abeni
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 <pabeni@redhat.com> Tested-by: Gang Yan <yangang@kylinos.cn> Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org> Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org> Link: https://patch.msgid.link/20260807-net-next-mptcp-oooq-pruning-v3-7-dbc1eb853cc3@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-08-11mptcp: avoid code duplication in __mptcp_move_skb()Paolo Abeni
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 <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/20260807-net-next-mptcp-oooq-pruning-v3-6-dbc1eb853cc3@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-08-11mptcp: enforce hard limit on backlog flushingPaolo Abeni
Currently a wild producer could keep the backlog flushing operation spinning for an unbound time. Since the previous patch, the amount of data present in the backlog is hard-limited. Move the backlog len update at the end of the flush loop to prevent it spinning forever. Also, no need to splice back the remaining skbs list into the backlog, as such list is always empty after each backlog processing loop. 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/20260807-net-next-mptcp-oooq-pruning-v3-5-dbc1eb853cc3@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-08-11mptcp: explicitly drop over memory limitsPaolo Abeni
Currently the enforcement of the rcvbuf constraint is implemented when moving the skbs into the msk receive or OoO queue, keeping the incoming skbs in the subflow queue when over limits. Under significant memory pressure the above can cause permanent data transfer stalls, as the skb needed to make forward progress can be stuck in a subflow queue. Over memory limits, drop the incoming skb, relying on MPTCP-level retransmissions. Note that fallback socket must perform the limit before the skb reaches the subflow-level queue, as dropping an in-sequence already acked skb would break the stream. This is not a complete fix for the stall issue, as the drop strategy needs refinements that will come in the next patches. 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/20260807-net-next-mptcp-oooq-pruning-v3-4-dbc1eb853cc3@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-08-11mptcp: let the retrans scheduler do its jobPaolo Abeni
Currently the MPTCP core enforces that when MPTCP-level retrans timer fires, at most a single dfrag is retransmitted. In some corner-cases, it may be necessary to retransmit multiple dfrags, and the MPTCP socket will need to wait multiple retrans timeout to accomplish that. Remove the mentioned constraint, allowing to transmit multiple dfrags per retrans period, as long as the scheduler keeps selecting subflows for retransmissions and pending data is available in the rtx queue. The default scheduler will transmit a dfrag per available subflow. Tested-by: Gang Yan <yangang@kylinos.cn> Tested-by: Geliang Tang <geliang@kernel.org> Acked-by: Geliang Tang <geliang@kernel.org> Signed-off-by: Paolo Abeni <pabeni@redhat.com> Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org> Link: https://patch.msgid.link/20260807-net-next-mptcp-oooq-pruning-v3-3-dbc1eb853cc3@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-08-11mptcp: move the stale logic out of retrans schedulerPaolo Abeni
This allow separating the stale logic invocation and the retrans scheduler, and will simplify the next patch. It's also a cleaner design as the retrans scheduler has currently too many side effects. As a possible downside, the retrans work will now traverse the subflows list additional times; that does not matter much, as this is slowpath. While at it, pick more accurate names for the involved helpers and explicitly note that the per subflow stale data is under msk socket lock protection. The scheduler and the stale logic may observe different subflow statues, as no subflow lock is acquired. This is intentional and not harmful, worst case leading to slower retransmissions. 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/20260807-net-next-mptcp-oooq-pruning-v3-2-dbc1eb853cc3@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-08-11mptcp: move the retrans loop to a separate helperPaolo Abeni
This is a cleanup in order to make the next patch simpler. No functional change intended. Tested-by: Gang Yan <yangang@kylinos.cn> Tested-by: Geliang Tang <geliang@kernel.org> Acked-by: Geliang Tang <geliang@kernel.org> Signed-off-by: Paolo Abeni <pabeni@redhat.com> Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org> Link: https://patch.msgid.link/20260807-net-next-mptcp-oooq-pruning-v3-1-dbc1eb853cc3@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-08-06mptcp: reclaim forward-allocated memory on RX path errorsPaolo Abeni
After commit 9db5b3cec4ec ("mptcp: borrow forward memory from subflow"), errors in the receive path prior to queueing skbs into the receive queue do not trigger forward-allocated memory reclaiming. Prevent forward memory from growing unboundedly in pathological drop scenarios by explicitly reclaiming memory when skbs are dropped. Fixes: 9db5b3cec4ec ("mptcp: borrow forward memory from subflow") Cc: stable@vger.kernel.org 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/20260803-net-mptcp-misc-fixes-7-2-rc6-v2-8-b8f496d71664@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-07-23mptcp: fix stale skb->sk reference on subflow closeKalpan Jani
The backlog list is updated by mptcp_data_ready() under mptcp_data_lock(). The cleanup of backlog references to a closing subflow, however, was performed in mptcp_close_ssk(), before __mptcp_close_ssk() acquires the ssk lock, and while holding neither the ssk lock nor mptcp_data_lock(). Because that traversal ran without mptcp_data_lock(), concurrent softirq RX processing on another CPU (subflow_data_ready() -> mptcp_data_ready() -> __mptcp_add_backlog(), under mptcp_data_lock()) could add a backlog entry referencing the ssk while the cleanup loop was in progress. Such an entry could be missed by the cleanup, or the concurrent list update could corrupt the traversal, leaving skb->sk pointing at the ssk after it is freed. A later mptcp_backlog_purge() then dereferences the stale pointer, triggering a warning in inet_sock_destruct() (ssk->sk_rmem_alloc != 0) followed by a use-after-free in mptcp_backlog_purge(). Fix this by moving the backlog cleanup into __mptcp_close_ssk(), after subflow->closing is set to 1 and while the ssk lock is still held, serialized under mptcp_data_lock(). The cleanup runs only on the push path (MPTCP_CF_PUSH), where backlog references accumulate; on other teardown paths the caller already handles cleanup. With subflow->closing set and mptcp_data_lock() held across the purge, any concurrent mptcp_data_ready() either completes its enqueue before the purge runs and is caught, or observes closing=1 and bails out. Once mptcp_data_unlock() is reached, no new skb referencing the ssk can be enqueued, so the cleanup is exhaustive. Remove the unprotected traversal from mptcp_close_ssk() entirely. Fixes: ee458a3f314e ("mptcp: introduce mptcp-level backlog") Cc: stable@vger.kernel.org Suggested-by: Paolo Abeni <pabeni@redhat.com> Reported-by: Matthieu Baerts (NGI0) <matttbe@kernel.org> Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/621 Signed-off-by: Kalpan Jani <kalpan.jani@mpiricsoftware.com> Acked-by: Paolo Abeni <pabeni@redhat.com> Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org> Link: https://patch.msgid.link/20260722-net-mptcp-misc-fixes-7-2-rc5-v1-3-6fb595bc86ef@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-07-23mptcp: decrement subflows counter on failed passive joinChenguang Zhao
mptcp_pm_allow_new_subflow() increments extra_subflows before __mptcp_finish_join() on the passive MP_JOIN path. In case of race conditions, the subflow is dropped without calling mptcp_close_ssk(), so the counter is not rolled back. Call mptcp_pm_close_subflow() when the join completion fails to decrement the subflows counter. Fixes: 10f6d46c943d ("mptcp: fix race between MP_JOIN and close") Cc: stable@vger.kernel.org Signed-off-by: Chenguang Zhao <zhaochenguang@kylinos.cn> Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org> Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org> Link: https://patch.msgid.link/20260722-net-mptcp-misc-fixes-7-2-rc5-v1-1-6fb595bc86ef@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-06-03mptcp: check desc->count in read_sockGang Yan
__tcp_read_sock() checks desc->count after each skb is consumed and breaks the loop when it reaches 0. The MPTCP variant lacks this check. This is a functional bug, other subsystems also rely on this check: TLS strparser sets desc->count to 0 once a full TLS record is assembled and depends on this break to stop reading. Add the same desc->count check to __mptcp_read_sock(), mirroring __tcp_read_sock(). Fixes: 250d9766a984 ("mptcp: implement .read_sock") Cc: stable@vger.kernel.org Co-developed-by: Geliang Tang <geliang@kernel.org> Signed-off-by: Geliang Tang <geliang@kernel.org> Signed-off-by: Gang Yan <yangang@kylinos.cn> Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org> Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org> Link: https://patch.msgid.link/20260602-net-mptcp-misc-fixes-7-1-rc7-v2-9-856831229976@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-06-03mptcp: fix retransmission loop when csum is enabledPaolo Abeni
Sashiko noted that retransmission with csum enabled can actually transmit new data, but currently the relevant code does not update accordingly snd_nxt. The may cause incoming ack drop and an endless retransmission loop. Address the issue incrementing snd_nxt as needed. Fixes: 4e14867d5e91 ("mptcp: tune re-injections for csum enabled mode") Cc: stable@vger.kernel.org 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/20260602-net-mptcp-misc-fixes-7-1-rc7-v2-2-856831229976@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-06-03mptcp: fix missing wakeups in edge scenariosPaolo Abeni
The mptcp_recvmsg() can fill MPTCP socket receive queue via mptcp_move_skbs(), but currently does not try to wakeup any listener, because the same process is going to check the receive queue soon. When multiple threads are reading from the same fd, the above can cause stall. Add the missing wakeup. Fixes: 6771bfd9ee24 ("mptcp: update mptcp ack sequence from work queue") Cc: stable@vger.kernel.org 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/20260602-net-mptcp-misc-fixes-7-1-rc7-v2-1-856831229976@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-05-19mptcp: reset rcv wnd on disconnectPaolo Abeni
If the MPTCP socket fallback to TCP before the MP handshake completion, the IASN remain 0, and the rcv_wnd_sent field is not explicitly initialized, just incremented over time with the data transfer. At disconnect time such value is not cleared. If the next connection falls back to TCP before the MP handshake completion, the data transfer will keep incrementing the receive window end sequence starting from the last value used in the previous connection: the announced window will be unrelated from the actual receiver buffer size and likely too big. Address the issue zeroing the field at disconnect time. Fixes: b29fcfb54cd7 ("mptcp: full disconnect implementation") Cc: stable@vger.kernel.org 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-v2-4-701e96419f2f@kernel.org Signed-off-by: Paolo Abeni <pabeni@redhat.com>
2026-05-19mptcp: do not drop partial packetsShardul Bankar
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: ab174ad8ef76 ("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>
2026-04-28mptcp: fastclose msk when linger time is 0Matthieu Baerts (NGI0)
The SO_LINGER socket option has been supported for a while with MPTCP sockets [1], but it didn't cause the equivalent of a TCP reset as expected when enabled and its time was set to 0. This was causing some behavioural differences with TCP where some connections were not promptly stopped as expected. To fix that, an extra condition is checked at close() time before sending an MP_FASTCLOSE, the MPTCP equivalent of a TCP reset. Note that backporting up to [1] will be difficult as more changes are needed to be able to send MP_FASTCLOSE. It seems better to stop at [2], which was supposed to already imitate TCP. Validated with MPTCP packetdrill tests [3]. Fixes: 268b12387460 ("mptcp: setsockopt: support SO_LINGER") [1] Fixes: d21f83485518 ("mptcp: use fastclose on more edge scenarios") [2] Cc: stable@vger.kernel.org Reported-by: Lance Tuller <lance@lance0.com> Closes: https://github.com/lance0/xfr/pull/67 Link: https://github.com/multipath-tcp/packetdrill/pull/196 [3] Reviewed-by: Mat Martineau <martineau@kernel.org> Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org> Link: https://patch.msgid.link/20260427-net-mptcp-misc-fixes-7-1-rc2-v1-3-7432b7f279fa@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-04-23mptcp: sync the msk->sndbuf at accept() timeGang Yan
On passive MPTCP connections, the msk sndbuf is not updated correctly. The root cause is an order issue in the accept path: - tcp_check_req() -> subflow_syn_recv_sock() -> mptcp_sk_clone_init() calls __mptcp_propagate_sndbuf() to copy the ssk sndbuf into msk - Later, tcp_child_process() -> tcp_init_transfer() -> tcp_sndbuf_expand() grows the ssk sndbuf. So __mptcp_propagate_sndbuf() runs before the ssk sndbuf has been expanded and the msk ends up with a much smaller sndbuf than the subflow: MPTCP: msk->sndbuf:20480, msk->first->sndbuf:2626560 Fix this by moving the __mptcp_propagate_sndbuf() call from mptcp_sk_clone_init() -- the ssk sndbuf is not yet finalized there -- to __mptcp_propagate_sndbuf() at accept() time, when the ssk sndbuf has been fully expanded by tcp_sndbuf_expand(). Fixes: 8005184fd1ca ("mptcp: refactor sndbuf auto-tuning") Cc: stable@vger.kernel.org Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/602 Signed-off-by: Gang Yan <yangang@kylinos.cn> Acked-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/20260420-net-mptcp-sync-sndbuf-accept-v1-1-e3523e3aeb44@kernel.org Signed-off-by: Paolo Abeni <pabeni@redhat.com>
2026-04-09Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/netJakub Kicinski
Cross-merge networking fixes after downstream PR (net-7.0-rc8). Conflicts: net/ipv6/seg6_iptunnel.c c3812651b522f ("seg6: separate dst_cache for input and output paths in seg6 lwtunnel") 78723a62b969a ("seg6: add per-route tunnel source address") https://lore.kernel.org/adZhwtOYfo-0ImSa@sirena.org.uk net/ipv4/icmp.c fde29fd934932 ("ipv4: icmp: fix null-ptr-deref in icmp_build_probe()") d98adfbdd5c01 ("ipv4: drop ipv6_stub usage and use direct function calls") https://lore.kernel.org/adO3dccqnr6j-BL9@sirena.org.uk Adjacent changes: drivers/net/ethernet/stmicro/stmmac/chain_mode.c 51f4e090b9f8 ("net: stmmac: fix integer underflow in chain mode") 6b4286e05508 ("net: stmmac: rename STMMAC_GET_ENTRY() -> STMMAC_NEXT_ENTRY()") Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-04-08mptcp: add receive queue awareness in tcp_rcv_space_adjust()Paolo Abeni
This is the MPTCP counter-part of commit ea33537d8292 ("tcp: add receive queue awareness in tcp_rcv_space_adjust()"). Prior to this commit: ESTAB 33165568 0 192.168.255.2:5201 192.168.255.1:53380 \ skmem:(r33076416,rb33554432,t0,tb91136,f448,w0,o0,bl0,d0) After: ESTAB 3279168 0 192.168.255.2:5201 192.168.255.1]:53042 \ skmem:(r3190912,rb3719956,t0,tb91136,f1536,w0,o0,bl0,d0) Same throughput. Reviewed-by: Mat Martineau <martineau@kernel.org> Signed-off-by: Paolo Abeni <pabeni@redhat.com> Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org> Link: https://patch.msgid.link/20260407-net-next-mptcp-reduce-rbuf-v2-2-0d1d135bf6f6@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-04-08mptcp: better mptcp-level RTT estimatorPaolo Abeni
The current MPTCP-level RTT estimator has several issues. On high speed links, the MPTCP-level receive buffer auto-tuning happens with a frequency well above the TCP-level's one. That in turn can cause excessive/unneeded receive buffer increase. On such links, the initial rtt_us value is considerably higher than the actual delay, and the current mptcp_rcv_space_adjust() updates msk->rcvq_space.rtt_us with a period equal to the such field previous value. If the initial rtt_us is 40ms, its first update will happen after 40ms, even if the subflows see actual RTT orders of magnitude lower. Additionally: - setting the msk RTT to the maximum among all the subflows RTTs makes DRS constantly overshooting the rcvbuf size when a subflow has considerable higher latency than the other(s). - during unidirectional bulk transfers with multiple active subflows, the TCP-level RTT estimator occasionally sees considerably higher value than the real link delay, i.e. when the packet scheduler reacts to an incoming ACK on given subflow pushing data on a different subflow. - currently inactive but still open subflows (i.e. switched to backup mode) are always considered when computing the msk-level RTT. Address the all the issues above with a more accurate RTT estimation strategy: the MPTCP-level RTT is set to the minimum of all the subflows actually feeding data into the MPTCP receive buffer, using a small sliding window. While at it, also use EWMA to compute the msk-level scaling_ratio, to that MPTCP can avoid traversing the subflow list is mptcp_rcv_space_adjust(). Use some care to avoid updating msk and ssk level fields too often. Fixes: a6b118febbab ("mptcp: add receive buffer auto-tuning") Signed-off-by: Paolo Abeni <pabeni@redhat.com> Reviewed-by: Mat Martineau <martineau@kernel.org> Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org> Link: https://patch.msgid.link/20260407-net-next-mptcp-reduce-rbuf-v2-1-0d1d135bf6f6@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-04-08mptcp: fix slab-use-after-free in __inet_lookup_establishedJiayuan Chen
The ehash table lookups are lockless and rely on SLAB_TYPESAFE_BY_RCU to guarantee socket memory stability during RCU read-side critical sections. Both tcp_prot and tcpv6_prot have their slab caches created with this flag via proto_register(). However, MPTCP's mptcp_subflow_init() copies tcpv6_prot into tcpv6_prot_override during inet_init() (fs_initcall, level 5), before inet6_init() (module_init/device_initcall, level 6) has called proto_register(&tcpv6_prot). At that point, tcpv6_prot.slab is still NULL, so tcpv6_prot_override.slab remains NULL permanently. This causes MPTCP v6 subflow child sockets to be allocated via kmalloc (falling into kmalloc-4k) instead of the TCPv6 slab cache. The kmalloc-4k cache lacks SLAB_TYPESAFE_BY_RCU, so when these sockets are freed without SOCK_RCU_FREE (which is cleared for child sockets by design), the memory can be immediately reused. Concurrent ehash lookups under rcu_read_lock can then access freed memory, triggering a slab-use-after-free in __inet_lookup_established. Fix this by splitting the IPv6-specific initialization out of mptcp_subflow_init() into a new mptcp_subflow_v6_init(), called from mptcp_proto_v6_init() before protocol registration. This ensures tcpv6_prot_override.slab correctly inherits the SLAB_TYPESAFE_BY_RCU slab cache. Fixes: b19bc2945b40 ("mptcp: implement delegated actions") Cc: stable@vger.kernel.org Signed-off-by: Jiayuan Chen <jiayuan.chen@linux.dev> Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org> Link: https://patch.msgid.link/20260406031512.189159-1-jiayuan.chen@linux.dev Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-04-06tcp: add recv_should_stop helperGeliang Tang
Factor out a new helper tcp_recv_should_stop() from tcp_recvmsg_locked() and tcp_splice_read() to check whether to stop receiving. And use this helper in mptcp_recvmsg() and mptcp_splice_read() to reduce redundant code. Suggested-by: Paolo Abeni <pabeni@redhat.com> Acked-by: Mat Martineau <martineau@kernel.org> Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn> Acked-by: Matthieu Baerts (NGI0) <matttbe@kernel.org> Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org> Link: https://patch.msgid.link/20260403-net-next-mptcp-msg_eor-misc-v1-3-b0b33bea3fed@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-04-06mptcp: preserve MSG_EOR semantics in sendmsg pathGang Yan
Extend MPTCP's sendmsg handling to recognize and honor the MSG_EOR flag, which marks the end of a record for application-level message boundaries. Data fragments tagged with MSG_EOR are explicitly marked in the mptcp_data_frag structure and skb context to prevent unintended coalescing with subsequent data chunks. This ensures the intent of applications using MSG_EOR is preserved across MPTCP subflows, maintaining consistent message segmentation behavior. Signed-off-by: Gang Yan <yangang@kylinos.cn> Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org> Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org> Link: https://patch.msgid.link/20260403-net-next-mptcp-msg_eor-misc-v1-2-b0b33bea3fed@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-04-06mptcp: reduce 'overhead' from u16 to u8Gang Yan
The 'overhead' in struct mptcp_data_frag can safely use u8, as it represents 'alignment + sizeof(mptcp_data_frag)'. With a maximum alignment of 7('ALIGN(1, sizeof(long)) - 1'), the overhead is at most 47, well below U8_MAX and validated with BUILD_BUG_ON(). This patch also adds a field named 'unused' for further extensions. Signed-off-by: Gang Yan <yangang@kylinos.cn> Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org> Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org> Link: https://patch.msgid.link/20260403-net-next-mptcp-msg_eor-misc-v1-1-b0b33bea3fed@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-04-02Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/netJakub Kicinski
Cross-merge networking fixes after downstream PR (net-7.0-rc7). Conflicts: net/vmw_vsock/af_vsock.c b18c83388874 ("vsock: initialize child_ns_mode_locked in vsock_net_init()") 0de607dc4fd8 ("vsock: add G2H fallback for CIDs not owned by H2G transport") Adjacent changes: drivers/net/ethernet/broadcom/bnxt/bnxt_ethtool.c ceee35e5674a ("bnxt_en: Refactor some basic ring setup and adjustment logic") 57cdfe0dc70b ("bnxt_en: Resize RSS contexts on channel count change") drivers/net/wireless/intel/iwlwifi/mld/mac80211.c 4d56037a02bd ("wifi: iwlwifi: mld: block EMLSR during TDLS connections") 687a95d204e7 ("wifi: iwlwifi: mld: correctly set wifi generation data") drivers/net/wireless/intel/iwlwifi/mld/scan.h b6045c899e37 ("wifi: iwlwifi: mld: Refactor scan command handling") ec66ec6a5a8f ("wifi: iwlwifi: mld: Fix MLO scan timing") drivers/net/wireless/intel/iwlwifi/mvm/fw.c 078df640ef05 ("wifi: iwlwifi: mld: add support for iwl_mcc_allowed_ap_type_cmd v 2") 323156c3541e ("wifi: iwlwifi: mvm: don't send a 6E related command when not supported") Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-03-31mptcp: fix soft lockup in mptcp_recvmsg()Li Xiasong
syzbot reported a soft lockup in mptcp_recvmsg() [0]. When receiving data with MSG_PEEK | MSG_WAITALL flags, the skb is not removed from the sk_receive_queue. This causes sk_wait_data() to always find available data and never perform actual waiting, leading to a soft lockup. Fix this by adding a 'last' parameter to track the last peeked skb. This allows sk_wait_data() to make informed waiting decisions and prevent infinite loops when MSG_PEEK is used. [0]: watchdog: BUG: soft lockup - CPU#2 stuck for 156s! [server:1963] Modules linked in: CPU: 2 UID: 0 PID: 1963 Comm: server Not tainted 6.19.0-rc8 #61 PREEMPT(none) Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014 RIP: 0010:sk_wait_data+0x15/0x190 Code: 80 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 41 56 41 55 41 54 49 89 f4 55 48 89 d5 53 48 89 fb <48> 83 ec 30 65 48 8b 05 17 a4 6b 01 48 89 44 24 28 31 c0 65 48 8b RSP: 0018:ffffc90000603ca0 EFLAGS: 00000246 RAX: 0000000000000000 RBX: ffff888102bf0800 RCX: 0000000000000001 RDX: 0000000000000000 RSI: ffffc90000603d18 RDI: ffff888102bf0800 RBP: 0000000000000000 R08: 0000000000000002 R09: 0000000000000101 R10: 0000000000000000 R11: 0000000000000075 R12: ffffc90000603d18 R13: ffff888102bf0800 R14: ffff888102bf0800 R15: 0000000000000000 FS: 00007f6e38b8c4c0(0000) GS:ffff8881b877e000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000055aa7bff1680 CR3: 0000000105cbe000 CR4: 00000000000006f0 Call Trace: <TASK> mptcp_recvmsg+0x547/0x8c0 net/mptcp/protocol.c:2329 inet_recvmsg+0x11f/0x130 net/ipv4/af_inet.c:891 sock_recvmsg+0x94/0xc0 net/socket.c:1100 __sys_recvfrom+0xb2/0x130 net/socket.c:2256 __x64_sys_recvfrom+0x1f/0x30 net/socket.c:2267 do_syscall_64+0x59/0x2d0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x76/0x7e arch/x86/entry/entry_64.S:131 RIP: 0033:0x7f6e386a4a1d Code: 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 8d 05 f1 de 2c 00 41 89 ca 8b 00 85 c0 75 20 45 31 c9 45 31 c0 b8 2d 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 6b f3 c3 66 0f 1f 84 00 00 00 00 00 41 56 41 RSP: 002b:00007ffc3c4bb078 EFLAGS: 00000246 ORIG_RAX: 000000000000002d RAX: ffffffffffffffda RBX: 000000000000861e RCX: 00007f6e386a4a1d RDX: 00000000000003ff RSI: 00007ffc3c4bb150 RDI: 0000000000000004 RBP: 00007ffc3c4bb570 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000103 R11: 0000000000000246 R12: 00005605dbc00be0 R13: 00007ffc3c4bb650 R14: 0000000000000000 R15: 0000000000000000 </TASK> Fixes: 8e04ce45a8db ("mptcp: fix MSG_PEEK stream corruption") Signed-off-by: Li Xiasong <lixiasong1@huawei.com> Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org> Link: https://patch.msgid.link/20260330120335.659027-1-lixiasong1@huawei.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-03-02net: remove addr_len argument of recvmsg() handlersEric Dumazet
Use msg->msg_namelen as a place holder instead of a temporary variable, notably in inet[6]_recvmsg(). This removes stack canaries and allows tail-calls. $ scripts/bloat-o-meter -t vmlinux.old vmlinux add/remove: 0/0 grow/shrink: 2/19 up/down: 26/-532 (-506) Function old new delta rawv6_recvmsg 744 767 +23 vsock_dgram_recvmsg 55 58 +3 vsock_connectible_recvmsg 50 47 -3 unix_stream_recvmsg 161 158 -3 unix_seqpacket_recvmsg 62 59 -3 unix_dgram_recvmsg 42 39 -3 tcp_recvmsg 546 543 -3 mptcp_recvmsg 1568 1565 -3 ping_recvmsg 806 800 -6 tcp_bpf_recvmsg_parser 983 974 -9 ip_recv_error 588 576 -12 ipv6_recv_rxpmtu 442 428 -14 udp_recvmsg 1243 1224 -19 ipv6_recv_error 1046 1024 -22 udpv6_recvmsg 1487 1461 -26 raw_recvmsg 465 437 -28 udp_bpf_recvmsg 1027 984 -43 sock_common_recvmsg 103 27 -76 inet_recvmsg 257 175 -82 inet6_recvmsg 257 175 -82 tcp_bpf_recvmsg 663 568 -95 Total: Before=25143834, After=25143328, chg -0.00% Signed-off-by: Eric Dumazet <edumazet@google.com> Reviewed-by: Willem de Bruijn <willemb@google.com> Link: https://patch.msgid.link/20260227151120.1346573-1-edumazet@google.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-02-10mptcp: allow overridden write_space to be invokedGeliang Tang
Future extensions with psock will override their own sk->sk_write_space callback. This patch ensures that the overridden sk_write_space can be invoked by MPTCP. INDIRECT_CALL is used to keep the default path optimised. Note that sk->sk_write_space was never called directly with MPTCP sockets, so changing it to sk_stream_write_space in the init, and using it from mptcp_write_space() is not supposed to change the current behaviour. This patch is shared early to ease discussions around future RFC and avoid confusions with this "fix" that is needed for different future extensions. Suggested-by: Paolo Abeni <pabeni@redhat.com> Co-developed-by: Gang Yan <yangang@kylinos.cn> Signed-off-by: Gang Yan <yangang@kylinos.cn> Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn> Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org> Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org> Link: https://patch.msgid.link/20260206-net-next-mptcp-write_space-override-v2-1-e0b12be818c6@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-02-04mptcp: Change some dubious min_t(int, ...) to min()David Laight
There are two: min_t(int, xxx, mptcp_wnd_end(msk) - msk->snd_nxt); Both mptcp_wnd_end(msk) and msk->snd_nxt are u64, their difference (aka the window size) might be limited to 32 bits - but that isn't knowable from this code. So checks being added to min_t() detect the potential discard of significant bits. Provided the 'avail_size' and return of mptcp_check_allowed_size() are changed to an unsigned type (size_t matches the type the caller uses) both min_t() can be changed to min(). Signed-off-by: David Laight <david.laight.linux@gmail.com> Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org> [ wrapped too long lines when declaring mptcp_check_allowed_size() ] Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org> Link: https://patch.msgid.link/20260203-net-next-mptcp-misc-feat-6-20-v1-6-31ec8bfc56d1@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-02-04trace: mptcp: add mptcp_rcvbuf_grow tracepointPaolo Abeni
Similar to tcp, provide a new tracepoint to better understand mptcp_rcv_space_adjust() behavior, which presents many artifacts. Note that the used format string is so long that I preferred wrap it, contrary to guidance for quoted strings. Reviewed-by: Mat Martineau <martineau@kernel.org> Signed-off-by: Paolo Abeni <pabeni@redhat.com> Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org> Link: https://patch.msgid.link/20260203-net-next-mptcp-misc-feat-6-20-v1-4-31ec8bfc56d1@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-02-04mptcp: consolidate rcv space initPaolo Abeni
MPTCP uses several calls of the mptcp_rcv_space_init() helper to initialize the receive space, with a catch-up call in mptcp_rcv_space_adjust(). Drop all the other strictly not needed invocations and move constant fields initialization at socket init/reset time. This removes a bit of complexity from mptcp DRS code. No functional changes intended. Reviewed-by: Mat Martineau <martineau@kernel.org> Signed-off-by: Paolo Abeni <pabeni@redhat.com> Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org> Link: https://patch.msgid.link/20260203-net-next-mptcp-misc-feat-6-20-v1-3-31ec8bfc56d1@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-02-04mptcp: fix receive space timestamp initializationPaolo Abeni
MPTCP initialize the receive buffer stamp in mptcp_rcv_space_init(), using the provided subflow stamp. Such helper is invoked in several places; for passive sockets, space init happened at clone time. In such scenario, MPTCP ends-up accesses the subflow stamp before its initialization, leading to quite randomic timing for the first receive buffer auto-tune event, as the timestamp for newly created subflow is not refreshed there. Fix the issue moving the stamp initialization out of the mentioned helper, at the data transfer start, and always using a fresh timestamp. Fixes: 013e3179dbd2 ("mptcp: fix rcv space initialization") Reviewed-by: Mat Martineau <martineau@kernel.org> Signed-off-by: Paolo Abeni <pabeni@redhat.com> Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org> Link: https://patch.msgid.link/20260203-net-next-mptcp-misc-feat-6-20-v1-2-31ec8bfc56d1@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-02-04mptcp: do not account for OoO in mptcp_rcvbuf_grow()Paolo Abeni
MPTCP-level OoOs are physiological when multiple subflows are active concurrently and will not cause retransmissions nor are caused by drops. Accounting for them in mptcp_rcvbuf_grow() causes the rcvbuf slowly drifting towards tcp_rmem[2]. Remove such accounting. Note that subflows will still account for TCP-level OoO when the MPTCP-level rcvbuf is propagated. This also closes a subtle and very unlikely race condition with rcvspace init; active sockets with user-space holding the msk-level socket lock, could complete such initialization in the receive callback, after that the first OoO data reaches the rcvbuf and potentially triggering a divide by zero Oops. Fixes: e118cdc34dd1 ("mptcp: rcvbuf auto-tuning improvement") Signed-off-by: Paolo Abeni <pabeni@redhat.com> Reviewed-by: Mat Martineau <martineau@kernel.org> Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org> Link: https://patch.msgid.link/20260203-net-next-mptcp-misc-feat-6-20-v1-1-31ec8bfc56d1@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-02-02mptcp: implement .splice_readGeliang Tang
This patch implements .splice_read interface of mptcp struct proto_ops as mptcp_splice_read() with reference to tcp_splice_read(). Corresponding to __tcp_splice_read(), __mptcp_splice_read() is defined, invoking mptcp_read_sock() instead of tcp_read_sock(). mptcp_splice_read() is almost the same as tcp_splice_read(), except for sock_rps_record_flow(). Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn> Reviewed-by: Mat Martineau <martineau@kernel.org> Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org> Link: https://patch.msgid.link/20260130-net-next-mptcp-splice-v2-4-31332ba70d7f@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-02-02mptcp: implement .read_sockGeliang Tang
Current in-kernel TCP sockets -- i.e. from nvme_tcp_try_recv() -- need to call .read_sock interface of struct proto_ops, but it's not implemented in MPTCP. This patch implements it with reference to __tcp_read_sock() and __mptcp_recvmsg_mskq(). Corresponding to tcp_recv_skb(), a new helper for MPTCP named mptcp_recv_skb() is added to peek a skb from sk->sk_receive_queue. Compared with __mptcp_recvmsg_mskq(), mptcp_read_sock() uses sk->sk_rcvbuf as the max read length. The LISTEN status is checked before the while loop, and mptcp_recv_skb() and mptcp_cleanup_rbuf() are invoked after the loop. In the loop, all flags checks for __mptcp_recvmsg_mskq() are removed. Reviewed-by: Hannes Reinecke <hare@kernel.org> Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn> Reviewed-by: Mat Martineau <martineau@kernel.org> Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org> Link: https://patch.msgid.link/20260130-net-next-mptcp-splice-v2-2-31332ba70d7f@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-02-02mptcp: add eat_recv_skb helperGeliang Tang
This patch extracts the free skb related code in __mptcp_recvmsg_mskq() into a new helper mptcp_eat_recv_skb(). This new helper will be used in the next patch. Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn> Reviewed-by: Mat Martineau <martineau@kernel.org> Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org> Reviewed-by: Eric Dumazet <edumazet@google.com> Link: https://patch.msgid.link/20260130-net-next-mptcp-splice-v2-1-31332ba70d7f@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-01-28mptcp: only reset subflow errors when propagatedMatthieu Baerts (NGI0)
Some subflow socket errors need to be reported to the MPTCP socket: the initial subflow connect (MP_CAPABLE), and the ones from the fallback sockets. The others are not propagated. The issue is that sock_error() was used to retrieve the error, which was also resetting the sk_err field. Because of that, when notifying the userspace about subflow close events later on from the MPTCP worker, the ssk->sk_err field was always 0. Now, the error (sk_err) is only reset when propagating it to the msk. Fixes: 15cc10453398 ("mptcp: deliver ssk errors to msk") Cc: stable@vger.kernel.org Reviewed-by: Geliang Tang <geliang@kernel.org> Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org> Link: https://patch.msgid.link/20260127-net-mptcp-dup-nl-events-v1-3-7f71e1bc4feb@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-01-28mptcp: avoid dup SUB_CLOSED events after disconnectMatthieu Baerts (NGI0)
In case of subflow disconnect(), which can also happen with the first subflow in case of errors like timeout or reset, mptcp_subflow_ctx_reset will reset most fields from the mptcp_subflow_context structure, including close_event_done. Then, when another subflow is closed, yet another SUB_CLOSED event for the disconnected initial subflow is sent. Because of the previous reset, there are no source address and destination port. A solution is then to also check the subflow's local id: it shouldn't be negative anyway. Another solution would be not to reset subflow->close_event_done at disconnect time, but when reused. But then, probably the whole reset could be done when being reused. Let's not change this logic, similar to TCP with tcp_disconnect(). Fixes: d82809b6c5f2 ("mptcp: avoid duplicated SUB_CLOSED events") Cc: stable@vger.kernel.org Reported-by: Marco Angaroni <marco.angaroni@italtel.com> Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/603 Reviewed-by: Geliang Tang <geliang@kernel.org> Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org> Link: https://patch.msgid.link/20260127-net-mptcp-dup-nl-events-v1-1-7f71e1bc4feb@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2025-12-23mptcp: ensure context reset on disconnect()Paolo Abeni
After the blamed commit below, if the MPC subflow is already in TCP_CLOSE status or has fallback to TCP at mptcp_disconnect() time, mptcp_do_fastclose() skips setting the `send_fastclose flag` and the later __mptcp_close_ssk() does not reset anymore the related subflow context. Any later connection will be created with both the `request_mptcp` flag and the msk-level fallback status off (it is unconditionally cleared at MPTCP disconnect time), leading to a warning in subflow_data_ready(): WARNING: CPU: 26 PID: 8996 at net/mptcp/subflow.c:1519 subflow_data_ready (net/mptcp/subflow.c:1519 (discriminator 13)) Modules linked in: CPU: 26 UID: 0 PID: 8996 Comm: syz.22.39 Not tainted 6.18.0-rc7-05427-g11fc074f6c36 #1 PREEMPT(voluntary) Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 RIP: 0010:subflow_data_ready (net/mptcp/subflow.c:1519 (discriminator 13)) Code: 90 0f 0b 90 90 e9 04 fe ff ff e8 b7 1e f5 fe 89 ee bf 07 00 00 00 e8 db 19 f5 fe 83 fd 07 0f 84 35 ff ff ff e8 9d 1e f5 fe 90 <0f> 0b 90 e9 27 ff ff ff e8 8f 1e f5 fe 4c 89 e7 48 89 de e8 14 09 RSP: 0018:ffffc9002646fb30 EFLAGS: 00010293 RAX: 0000000000000000 RBX: ffff88813b218000 RCX: ffffffff825c8435 RDX: ffff8881300b3580 RSI: ffffffff825c8443 RDI: 0000000000000005 RBP: 000000000000000b R08: ffffffff825c8435 R09: 000000000000000b R10: 0000000000000005 R11: 0000000000000007 R12: ffff888131ac0000 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 FS: 00007f88330af6c0(0000) GS:ffff888a93dd2000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f88330aefe8 CR3: 000000010ff59000 CR4: 0000000000350ef0 Call Trace: <TASK> tcp_data_ready (net/ipv4/tcp_input.c:5356) tcp_data_queue (net/ipv4/tcp_input.c:5445) tcp_rcv_state_process (net/ipv4/tcp_input.c:7165) tcp_v4_do_rcv (net/ipv4/tcp_ipv4.c:1955) __release_sock (include/net/sock.h:1158 (discriminator 6) net/core/sock.c:3180 (discriminator 6)) release_sock (net/core/sock.c:3737) mptcp_sendmsg (net/mptcp/protocol.c:1763 net/mptcp/protocol.c:1857) inet_sendmsg (net/ipv4/af_inet.c:853 (discriminator 7)) __sys_sendto (net/socket.c:727 (discriminator 15) net/socket.c:742 (discriminator 15) net/socket.c:2244 (discriminator 15)) __x64_sys_sendto (net/socket.c:2247) do_syscall_64 (arch/x86/entry/syscall_64.c:63 (discriminator 1) arch/x86/entry/syscall_64.c:94 (discriminator 1)) entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130) RIP: 0033:0x7f883326702d Address the issue setting an explicit `fastclosing` flag at fastclose time, and checking such flag after mptcp_do_fastclose(). Fixes: ae155060247b ("mptcp: fix duplicate reset on fastclose") Cc: stable@vger.kernel.org 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/20251212-net-mptcp-subflow_data_ready-warn-v1-2-d1f9fd1c36c8@kernel.org Signed-off-by: Paolo Abeni <pabeni@redhat.com>
2025-12-08mptcp: avoid deadlock on fallback while reinjectingPaolo Abeni
Jakub reported an MPTCP deadlock at fallback time: WARNING: possible recursive locking detected 6.18.0-rc7-virtme #1 Not tainted -------------------------------------------- mptcp_connect/20858 is trying to acquire lock: ff1100001da18b60 (&msk->fallback_lock){+.-.}-{3:3}, at: __mptcp_try_fallback+0xd8/0x280 but task is already holding lock: ff1100001da18b60 (&msk->fallback_lock){+.-.}-{3:3}, at: __mptcp_retrans+0x352/0xaa0 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(&msk->fallback_lock); lock(&msk->fallback_lock); *** DEADLOCK *** May be due to missing lock nesting notation 3 locks held by mptcp_connect/20858: #0: ff1100001da18290 (sk_lock-AF_INET){+.+.}-{0:0}, at: mptcp_sendmsg+0x114/0x1bc0 #1: ff1100001db40fd0 (k-sk_lock-AF_INET#2){+.+.}-{0:0}, at: __mptcp_retrans+0x2cb/0xaa0 #2: ff1100001da18b60 (&msk->fallback_lock){+.-.}-{3:3}, at: __mptcp_retrans+0x352/0xaa0 stack backtrace: CPU: 0 UID: 0 PID: 20858 Comm: mptcp_connect Not tainted 6.18.0-rc7-virtme #1 PREEMPT(full) Hardware name: Bochs, BIOS Bochs 01/01/2011 Call Trace: <TASK> dump_stack_lvl+0x6f/0xa0 print_deadlock_bug.cold+0xc0/0xcd validate_chain+0x2ff/0x5f0 __lock_acquire+0x34c/0x740 lock_acquire.part.0+0xbc/0x260 _raw_spin_lock_bh+0x38/0x50 __mptcp_try_fallback+0xd8/0x280 mptcp_sendmsg_frag+0x16c2/0x3050 __mptcp_retrans+0x421/0xaa0 mptcp_release_cb+0x5aa/0xa70 release_sock+0xab/0x1d0 mptcp_sendmsg+0xd5b/0x1bc0 sock_write_iter+0x281/0x4d0 new_sync_write+0x3c5/0x6f0 vfs_write+0x65e/0xbb0 ksys_write+0x17e/0x200 do_syscall_64+0xbb/0xfd0 entry_SYSCALL_64_after_hwframe+0x4b/0x53 RIP: 0033:0x7fa5627cbc5e Code: 4d 89 d8 e8 14 bd 00 00 4c 8b 5d f8 41 8b 93 08 03 00 00 59 5e 48 83 f8 fc 74 11 c9 c3 0f 1f 80 00 00 00 00 48 8b 45 10 0f 05 <c9> c3 83 e2 39 83 fa 08 75 e7 e8 13 ff ff ff 0f 1f 00 f3 0f 1e fa RSP: 002b:00007fff1fe14700 EFLAGS: 00000202 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 00007fa5627cbc5e RDX: 0000000000001f9c RSI: 00007fff1fe16984 RDI: 0000000000000005 RBP: 00007fff1fe14710 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000202 R12: 00007fff1fe16920 R13: 0000000000002000 R14: 0000000000001f9c R15: 0000000000001f9c The packet scheduler could attempt a reinjection after receiving an MP_FAIL and before the infinite map has been transmitted, causing a deadlock since MPTCP needs to do the reinjection atomically from WRT fallback. Address the issue explicitly avoiding the reinjection in the critical scenario. Note that this is the only fallback critical section that could potentially send packets and hit the double-lock. Reported-by: Jakub Kicinski <kuba@kernel.org> Closes: https://netdev-ctrl.bots.linux.dev/logs/vmksft/mptcp-dbg/results/412720/1-mptcp-join-sh/stderr Fixes: f8a1d9b18c5e ("mptcp: make fallback action and fallback decision atomic") Cc: stable@vger.kernel.org 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/20251205-net-mptcp-misc-fixes-6-19-rc1-v1-4-9e4781a6c1b8@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2025-12-08mptcp: schedule rtx timer only after pushing dataPaolo Abeni
The MPTCP protocol usually schedule the retransmission timer only when there is some chances for such retransmissions to happen. With a notable exception: __mptcp_push_pending() currently schedule such timer unconditionally, potentially leading to unnecessary rtx timer expiration. The issue is present since the blamed commit below but become easily reproducible after commit 27b0e701d387 ("mptcp: drop bogus optimization in __mptcp_check_push()") Fixes: 33d41c9cd74c ("mptcp: more accurate timeout") Cc: stable@vger.kernel.org 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/20251205-net-mptcp-misc-fixes-6-19-rc1-v1-3-9e4781a6c1b8@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2025-11-27Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/netJakub Kicinski
Conflicts: net/xdp/xsk.c 0ebc27a4c67d ("xsk: avoid data corruption on cq descriptor number") 8da7bea7db69 ("xsk: add indirect call for xsk_destruct_skb") 30ed05adca4a ("xsk: use a smaller new lock for shared pool case") https://lore.kernel.org/20251127105450.4a1665ec@canb.auug.org.au https://lore.kernel.org/eb4eee14-7e24-4d1b-b312-e9ea738fefee@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
generated by cgit v1.2.3 (git 2.39.1) at 2026-09-13 20:43:47 +0000