Blamed commit moved the TIME_WAIT-derived ISN from the skb control
block to a per-CPU variable, assuming the value would always be consumed
by tcp_conn_request() for the same packet that wrote it. That assumption
is violated by multiple drop paths between the producer
(__this_cpu_write(tcp_tw_isn, isn) in tcp_v{4,6}_rcv()) and the consumer
(tcp_conn_request()):
- min_ttl / min_hopcount check
- xfrm policy check
- tcp_inbound_hash() MD5/AO mismatch
- tcp_filter() eBPF/SO_ATTACH_FILTER drop
- th->syn && th->fin discard in tcp_rcv_state_process() TCP_LISTEN
- psp_sk_rx_policy_check() in tcp_v{4,6}_do_rcv()
- tcp_checksum_complete() in tcp_v{4,6}_do_rcv()
- tcp_v{4,6}_cookie_check() returning NULL
When a packet is dropped on any of these paths, tcp_tw_isn is left set.
The next SYN processed on the same CPU then consumes the non zero value in
tcp_conn_request(), receiving a potentially predictable ISN.
This patch moves back tcp_tw_isn to skb->cb[], getting rid of the per-cpu
variable.
Note that tcp_v{4,6}_fill_cb() do not set it.
Very litle impact on overall code size/complexity:
$ scripts/bloat-o-meter -t vmlinux.old vmlinux.new
add/remove: 0/0 grow/shrink: 2/1 up/down: 8/-15 (-7)
Function old new delta
tcp_v6_rcv 3038 3042 +4
tcp_v4_rcv 3035 3039 +4
tcp_conn_request 2938 2923 -15
Total: Before=24436060, After=24436053, chg -0.00%
Fixes: 41eecbd712 ("tcp: replace TCP_SKB_CB(skb)->tcp_tw_isn with a per-cpu field")
Reported-by: Chris Mason <clm@meta.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com>
Link: https://patch.msgid.link/20260519084611.2485277-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
tcp_get_timestamping_opt_stats() intentionally runs lockless, we must
add READ_ONCE(), WRITE_ONCE() data_race() annotations to keep KCSAN happy.
Fixes: bb7c19f960 ("tcp: add related fields into SCM_TIMESTAMPING_OPT_STATS")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20260416200319.3608680-4-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
tcp_get_timestamping_opt_stats() does not own the socket lock,
this is intentional.
It calls tcp_get_info_chrono_stats() while other threads could
change chrono fields in tcp_chrono_set().
I do not think we need coherent TCP socket state snapshot
in tcp_get_timestamping_opt_stats(), I chose to only
add annotations to keep KCSAN happy.
Fixes: 1c885808e4 ("tcp: SOF_TIMESTAMPING_OPT_STATS option for SO_TIMESTAMPING")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20260416200319.3608680-2-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Commit under Fixes moved recomputing the window clamp to
tcp_measure_rcv_mss() (when scaling_ratio changes).
I suspect it missed the fact that we don't recompute the clamp
when rcvbuf is set. Until scaling_ratio changes we are
stuck with the old window clamp which may be based on
the small initial buffer. scaling_ratio may never change.
Inspired by Eric's recent commit d1361840f8 ("tcp: fix
SO_RCVLOWAT and RCVBUF autotuning") plumb the user action
thru to TCP and have it update the clamp.
A smaller fix would be to just have tcp_rcvbuf_grow()
adjust the clamp even if SOCK_RCVBUF_LOCK is set.
But IIUC this is what we were trying to get away from
in the first place.
Fixes: a2cbb16039 ("tcp: Update window clamping condition")
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Eric Dumazet <edumaze@google.com>
Link: https://patch.msgid.link/20260408001438.129165-1-kuba@kernel.org
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
sk_filter_trim_cap() will soon return the reason by value,
do the same for tcp_filter().
Note:
tcp_filter() is no longer inlined. Following patch will inline it again.
$ scripts/bloat-o-meter -t vmlinux.4 vmlinux.5
add/remove: 2/0 grow/shrink: 0/2 up/down: 186/-43 (143)
Function old new delta
tcp_filter - 154 +154
__pfx_tcp_filter - 32 +32
tcp_v4_rcv 3152 3143 -9
tcp_v6_rcv 3169 3135 -34
Total: Before=29722640, After=29722783, chg +0.00%
Signed-off-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20260409145625.2306224-5-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Small improvement in SYN processing, to directly call
tcp_v6_init_seq_and_ts_off() or tcp_v4_init_seq_and_ts_off().
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com>
Link: https://patch.msgid.link/20260410174950.745670-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Part of a stack canary removal from tcp_v{4,6}_rcv().
Return a drop_reason instead of a boolean, so that we no longer
have to pass the address of a local variable.
$ scripts/bloat-o-meter -t vmlinux.old vmlinux.new
add/remove: 0/0 grow/shrink: 0/3 up/down: 0/-37 (-37)
Function old new delta
tcp_v6_rcv 3133 3129 -4
tcp_v4_rcv 3206 3202 -4
tcp_add_backlog 1281 1252 -29
Total: Before=25567186, After=25567149, chg -0.00%
Signed-off-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20260409101147.1642967-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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>
(tcp_congestion_ops)->cwnd_event() is called very often, with
@event oscillating between CA_EVENT_TX_START and other values.
This is not branch prediction friendly.
Provide a new cwnd_event_tx_start pointer dedicated for CA_EVENT_TX_START.
Both BBR and CUBIC benefit from this change, since they only care
about CA_EVENT_TX_START.
No change in kernel size:
$ scripts/bloat-o-meter -t vmlinux.0 vmlinux
add/remove: 4/4 grow/shrink: 3/1 up/down: 564/-568 (-4)
Function old new delta
bbr_cwnd_event_tx_start - 450 +450
cubictcp_cwnd_event_tx_start - 70 +70
__pfx_cubictcp_cwnd_event_tx_start - 16 +16
__pfx_bbr_cwnd_event_tx_start - 16 +16
tcp_unregister_congestion_control 93 99 +6
tcp_update_congestion_control 518 521 +3
tcp_register_congestion_control 422 425 +3
__tcp_transmit_skb 3308 3306 -2
__pfx_cubictcp_cwnd_event 16 - -16
__pfx_bbr_cwnd_event 16 - -16
cubictcp_cwnd_event 80 - -80
bbr_cwnd_event 454 - -454
Total: Before=25240512, After=25240508, chg -0.00%
Signed-off-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20260323234920.1097858-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
By default, the Linux TCP implementation does not shrink the
advertised window (RFC 7323 calls this "window retraction") with the
following exceptions:
- When an incoming segment cannot be added due to the receive buffer
running out of memory. Since commit 8c670bdfa5 ("tcp: correct
handling of extreme memory squeeze") a zero window will be
advertised in this case. It turns out that reaching the required
memory pressure is easy when window scaling is in use. In the
simplest case, sending a sufficient number of segments smaller than
the scale factor to a receiver that does not read data is enough.
- Commit b650d953cd ("tcp: enforce receive buffer memory limits by
allowing the tcp window to shrink") addressed the "eating memory"
problem by introducing a sysctl knob that allows shrinking the
window before running out of memory.
However, RFC 7323 does not only state that shrinking the window is
necessary in some cases, it also formulates requirements for TCP
implementations when doing so (Section 2.4).
This commit addresses the receiver-side requirements: After retracting
the window, the peer may have a snd_nxt that lies within a previously
advertised window but is now beyond the retracted window. This means
that all incoming segments (including pure ACKs) will be rejected
until the application happens to read enough data to let the peer's
snd_nxt be in window again (which may be never).
To comply with RFC 7323, the receiver MUST honor any segment that
would have been in window for any ACK sent by the receiver and, when
window scaling is in effect, SHOULD track the maximum window sequence
number it has advertised. This patch tracks that maximum window
sequence number rcv_mwnd_seq throughout the connection and uses it in
tcp_sequence() when deciding whether a segment is acceptable.
rcv_mwnd_seq is updated together with rcv_wup and rcv_wnd in
tcp_select_window(). If we count tcp_sequence() as fast path, it is
read in the fast path. Therefore, rcv_mwnd_seq is put into rcv_wnd's
cacheline group.
The logic for handling received data in tcp_data_queue() is already
sufficient and does not need to be updated.
Signed-off-by: Simon Baatz <gmbnomis@gmail.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20260309-tcp_rfc7323_retract_wnd_rfc-v3-1-4c7f96b1ec69@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Majority of tcp_release_cb() calls do nothing at all.
Provide tcp_release_cb_cond() helper so that release_sock()
can avoid these calls.
Also hint the compiler that __release_sock() and wake_up()
are rarely called.
$ scripts/bloat-o-meter -t vmlinux.old vmlinux.new
add/remove: 0/0 grow/shrink: 0/1 up/down: 0/-77 (-77)
Function old new delta
release_sock 258 181 -77
Total: Before=25235790, After=25235713, chg -0.00%
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com>
Link: https://patch.msgid.link/20260310124451.2280968-1-edumazet@google.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
tcp_chrono_start() is small enough, and used in TCP sendmsg()
fast path (from tcp_skb_entail()).
Note clang is already inlining it from functions in tcp_output.c.
Inlining it improves performance and reduces bloat :
$ scripts/bloat-o-meter -t vmlinux.old vmlinux.new
add/remove: 0/2 grow/shrink: 1/0 up/down: 1/-84 (-83)
Function old new delta
tcp_skb_entail 280 281 +1
__pfx_tcp_chrono_start 16 - -16
tcp_chrono_start 68 - -68
Total: Before=25192434, After=25192351, chg -0.00%
Note that tcp_chrono_stop() is too big.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Neal Cardwell <ncardwell@google.com>
Link: https://patch.msgid.link/20260308123549.2924460-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
tcp_v4_early_demux() has a single caller : ip_rcv_finish_core().
Move it to net/ipv4/ip_input.c and mark it static, for possible
compiler/linker optimizations.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com>
Link: https://patch.msgid.link/20260306131130.654991-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
tcp_v6_early_demux() has a single caller : ip6_rcv_finish_core().
Move it to net/ipv6/ip6_input.c and mark it static, for possible
compiler/linker optimizations.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20260304022706.1062459-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Cross-merge networking fixes after downstream PR (net-7.0-rc3).
No conflicts.
Adjacent changes:
net/netfilter/nft_set_rbtree.c
fb7fb40163 ("netfilter: nf_tables: clone set on flush only")
3aea466a43 ("netfilter: nft_set_rbtree: don't disable bh when acquiring tree lock")
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Instead of using struct timespec64 in scm_timestamping_internal,
use ktime_t, saving 24 bytes in kernel stack.
This makes tcp_update_recv_tstamps() small enough to be inlined.
The ktime_t -> timespec64 conversions happen after socket lock
has been released in tcp_recvmsg(), and only if the application
requested them.
$ scripts/bloat-o-meter -t vmlinux.0 vmlinux
add/remove: 0/2 grow/shrink: 5/4 up/down: 146/-277 (-131)
Function old new delta
tcp_zerocopy_receive 2383 2425 +42
mptcp_recvmsg 1565 1607 +42
tcp_recvmsg_locked 3797 3823 +26
put_cmsg_scm_timestamping64 131 149 +18
put_cmsg_scm_timestamping 131 149 +18
__pfx_tcp_update_recv_tstamps 16 - -16
do_tcp_getsockopt 4024 4006 -18
tcp_recv_timestamp 474 430 -44
tcp_zc_handle_leftover 417 371 -46
__sock_recv_timestamp 1087 1031 -56
tcp_update_recv_tstamps 97 - -97
Total: Before=25223788, After=25223657, chg -0.00%
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Reviewed-by: Jason Xing <kerneljasonxing@gmail.com>
Link: https://patch.msgid.link/20260304012747.881644-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This reverts 28ee1b746f ("secure_seq: downgrade to per-host timestamp offsets")
tcp_tw_recycle went away in 2017.
Zhouyan Deng reported off-path TCP source port leakage via
SYN cookie side-channel that can be fixed in multiple ways.
One of them is to bring back TCP ports in TS offset randomization.
As a bonus, we perform a single siphash() computation
to provide both an ISN and a TS offset.
Fixes: 28ee1b746f ("secure_seq: downgrade to per-host timestamp offsets")
Reported-by: Zhouyan Deng <dengzhouyan_nwpu@163.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com>
Acked-by: Florian Westphal <fw@strlen.de>
Link: https://patch.msgid.link/20260302205527.1982836-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Cross-merge networking fixes after downstream PR (net-7.0-rc2).
Conflicts:
tools/testing/selftests/drivers/net/hw/rss_ctx.py
19c3a2a81d ("selftests: drv-net: rss: Generate unique ports for RSS context tests")
ce5a0f4612 ("selftests: drv-net: rss_ctx: test RSS contexts persist after ifdown/up")
include/net/inet_connection_sock.h
858d2a4f67 ("tcp: fix potential race in tcp_v6_syn_recv_sock()")
fcd3d039fa ("tcp: make tcp_v{4,6}_send_check() static")
https://lore.kernel.org/aZ8PSFLzBrEU3I89@sirena.org.uk
drivers/net/ethernet/mellanox/mlx5/core/en/xsk/setup.c
drivers/net/ethernet/mellanox/mlx5/core/en/xsk/pool.c
69050f8d6d ("treewide: Replace kmalloc with kmalloc_obj for non-scalar types")
bf4afc53b7 ("Convert 'alloc_obj' family to use the new default GFP_KERNEL argument")
8a96b9144f ("net/mlx5e: Alloc xsk channel param out of mlx5e_open_xsk()")
Adjacent changes:
net/netfilter/ipvs/ip_vs_ctl.c
c59bd9e62e ("ipvs: use more counters to avoid service lookups")
bf4afc53b7 ("Convert 'alloc_obj' family to use the new default GFP_KERNEL argument")
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
tcp_v{4,6}_send_check() are only called from tcp_output.c
and should be made static so that the compiler does not need
to put an out of line copy of them.
Remove (struct inet_connection_sock_af_ops) send_check field
and use instead @net_header_len.
Move @net_header_len close to @queue_xmit for data locality
as both are used in TCP tx fast path.
$ scripts/bloat-o-meter -t vmlinux.2 vmlinux.3
add/remove: 0/2 grow/shrink: 0/3 up/down: 0/-172 (-172)
Function old new delta
__tcp_transmit_skb 3426 3423 -3
tcp_v4_send_check 136 132 -4
mptcp_subflow_init 777 763 -14
__pfx_tcp_v6_send_check 16 - -16
tcp_v6_send_check 135 - -135
Total: Before=25143196, After=25143024, chg -0.00%
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com>
Link: https://patch.msgid.link/20260223100729.3761597-4-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Inline __tcp_v4_send_check(), like __tcp_v6_send_check().
Move tcp_v4_send_check() to tcp_output.c close to
its fast path caller (__tcp_transmit_skb()).
Note __tcp_v4_send_check() is still out-of-line for tcp4_gso_segment()
because it is called in an unlikely() section.
$ scripts/bloat-o-meter -t vmlinux.0 vmlinux.1
add/remove: 0/0 grow/shrink: 0/1 up/down: 0/-9 (-9)
Function old new delta
__tcp_v4_send_check 130 121 -9
Total: Before=25143100, After=25143091, chg -0.00%
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com>
Link: https://patch.msgid.link/20260223100729.3761597-2-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Code in tcp_v6_syn_recv_sock() after the call to tcp_v4_syn_recv_sock()
is done too late.
After tcp_v4_syn_recv_sock(), the child socket is already visible
from TCP ehash table and other cpus might use it.
Since newinet->pinet6 is still pointing to the listener ipv6_pinfo
bad things can happen as syzbot found.
Move the problematic code in tcp_v6_mapped_child_init()
and call this new helper from tcp_v4_syn_recv_sock() before
the ehash insertion.
This allows the removal of one tcp_sync_mss(), since
tcp_v4_syn_recv_sock() will call it with the correct
context.
Fixes: 1da177e4c3 ("Linux-2.6.12-rc2")
Reported-by: syzbot+937b5bbb6a815b3e5d0b@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/netdev/69949275.050a0220.2eeac1.0145.GAE@google.com/
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com>
Link: https://patch.msgid.link/20260217161205.2079883-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This helper is already (auto)inlined from IPv4 TCP stack.
Make it an inline function to benefit IPv6 as well.
$ scripts/bloat-o-meter -t vmlinux.old vmlinux.new
add/remove: 0/2 grow/shrink: 1/0 up/down: 30/-49 (-19)
Function old new delta
tcp_v6_rcv 3448 3478 +30
__pfx_tcp_filter 16 - -16
tcp_filter 33 - -33
Total: Before=24891904, After=24891885, chg -0.00%
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com>
Link: https://patch.msgid.link/20260205164329.3401481-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Before this patch, retransmitted SYN/ACK did not have a specific
synack_type; however, the upcoming patch needs to distinguish between
retransmitted and non-retransmitted SYN/ACK for AccECN negotiation to
transmit the fallback SYN/ACK during AccECN negotiation. Therefore, this
patch introduces a new synack_type (TCP_SYNACK_RETRANS).
Signed-off-by: Chia-Yu Chang <chia-yu.chang@nokia-bell-labs.com>
Acked-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20260131222515.8485-9-chia-yu.chang@nokia-bell-labs.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
When AccECN is not successfully negociated for a TCP flow, it defaults
fallback to classic ECN (RFC3168). However, L4S service will fallback
to non-ECN.
This patch enables congestion control module to control whether it
should not fallback to classic ECN after unsuccessful AccECN negotiation.
A new CA module flag (TCP_CONG_NO_FALLBACK_RFC3168) identifies this
behavior expected by the CA.
Signed-off-by: Chia-Yu Chang <chia-yu.chang@nokia-bell-labs.com>
Acked-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20260131222515.8485-6-chia-yu.chang@nokia-bell-labs.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Two flags for congestion control (CC) module are added in this patch
related to AccECN negotiation. First, a new flag (TCP_CONG_NEEDS_ACCECN)
defines that the CC expects to negotiate AccECN functionality using the
ECE, CWR and AE flags in the TCP header.
Second, during ECN negotiation, ECT(0) in the IP header is used. This
patch enables CC to control whether ECT(0) or ECT(1) should be used on
a per-segment basis. A new flag (TCP_CONG_ECT_1_NEGOTIATION) defines the
expected ECT value in the IP header by the CA when not-yet initialized
for the connection.
The detailed AccECN negotiaotn can be found in IETF RFC9768.
Co-developed-by: Olivier Tilmans <olivier.tilmans@nokia.com>
Signed-off-by: Olivier Tilmans <olivier.tilmans@nokia.com>
Signed-off-by: Ilpo Järvinen <ij@kernel.org>
Signed-off-by: Chia-Yu Chang <chia-yu.chang@nokia-bell-labs.com>
Acked-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20260131222515.8485-5-chia-yu.chang@nokia-bell-labs.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Export struct tcp_splice_state and tcp_splice_data_recv() in net/tcp.h
so that they can be used by MPTCP in the next patch.
Suggested-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>
Acked-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-v2-3-31332ba70d7f@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
tcp_rack_advance() is called from tcp_ack() and tcp_sacktag_one().
Moving it to tcp_input.c allows the compiler to inline it and save
both space and cpu cycles in TCP fast path.
$ scripts/bloat-o-meter -t vmlinux.1 vmlinux.2
add/remove: 0/2 grow/shrink: 1/1 up/down: 98/-132 (-34)
Function old new delta
tcp_ack 5741 5839 +98
tcp_sacktag_one 407 395 -12
__pfx_tcp_rack_advance 16 - -16
tcp_rack_advance 104 - -104
Total: Before=22572680, After=22572646, chg -0.00%
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com>
Link: https://patch.msgid.link/20260127032147.3498272-4-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
tcp_rack_update_reo_wnd() is called only once from tcp_ack()
Move it to tcp_input.c so that it can be inlined by the compiler
to save space and cpu cycles.
$ scripts/bloat-o-meter -t vmlinux.old vmlinux.new
add/remove: 0/2 grow/shrink: 1/0 up/down: 110/-153 (-43)
Function old new delta
tcp_ack 5631 5741 +110
__pfx_tcp_rack_update_reo_wnd 16 - -16
tcp_rack_update_reo_wnd 137 - -137
Total: Before=22572723, After=22572680, chg -0.00%
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com>
Link: https://patch.msgid.link/20260127032147.3498272-3-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
tcp_rate_check_app_limited() is used from tcp_sendmsg_locked()
fast path and from other callers.
Move it to tcp.c so that it can be inlined in tcp_sendmsg_locked().
Small increase of code, for better TCP performance.
$ scripts/bloat-o-meter -t vmlinux.old vmlinux.new
add/remove: 0/0 grow/shrink: 1/0 up/down: 87/0 (87)
Function old new delta
tcp_sendmsg_locked 4217 4304 +87
Total: Before=22566462, After=22566549, chg +0.00%
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Neal Cardwell <ncardwell@google.com>
Link: https://patch.msgid.link/20260121095923.3134639-3-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This function is called from one caller only, in TCP fast path.
Move it to tcp_input.c so that compiler can inline it.
$ scripts/bloat-o-meter -t vmlinux.old vmlinux.new
add/remove: 0/2 grow/shrink: 1/0 up/down: 226/-300 (-74)
Function old new delta
tcp_ack 5405 5631 +226
__pfx_tcp_rate_gen 16 - -16
tcp_rate_gen 284 - -284
Total: Before=22566536, After=22566462, chg -0.00%
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Neal Cardwell <ncardwell@google.com>
Link: https://patch.msgid.link/20260121095923.3134639-2-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
FDO/LTO are unable to inline tcp6_gro_receive() from ipv6_gro_receive()
Make sure tcp6_check_fraglist_gro() is only called only when needed,
so that compiler can leave it out-of-line.
$ scripts/bloat-o-meter -t vmlinux.1 vmlinux.2
add/remove: 2/0 grow/shrink: 3/1 up/down: 1123/-253 (870)
Function old new delta
ipv6_gro_receive 1069 1846 +777
tcp6_check_fraglist_gro - 272 +272
ipv6_offload_init 218 274 +56
__pfx_tcp6_check_fraglist_gro - 16 +16
ipv6_gro_complete 433 435 +2
tcp6_gro_receive 959 706 -253
Total: Before=22592662, After=22593532, chg +0.00%
Signed-off-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20260120164903.1912995-3-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
tcp_rate_skb_delivered() is only called from tcp_input.c.
Move it there and make it static.
Both gcc and clang are (auto)inlining it, TCP performance
is increased at a small space cost.
$ scripts/bloat-o-meter -t vmlinux.old vmlinux.new
add/remove: 0/2 grow/shrink: 3/0 up/down: 509/-187 (322)
Function old new delta
tcp_sacktag_walk 1682 1867 +185
tcp_ack 5230 5405 +175
tcp_shifted_skb 437 586 +149
__pfx_tcp_rate_skb_delivered 16 - -16
tcp_rate_skb_delivered 171 - -171
Total: Before=22566192, After=22566514, chg +0.00%
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Neal Cardwell <ncardwell@google.com>
Link: https://patch.msgid.link/20260118123204.2315993-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
It is only called from __tcp_transmit_skb() and __tcp_retransmit_skb().
Move it in tcp_output.c and make it static.
clang compiler is now able to inline it from __tcp_transmit_skb().
gcc compiler inlines it in the two callers, which is also fine.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Neal Cardwell <ncardwell@google.com>
Link: https://patch.msgid.link/20260114165109.1747722-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
The optional and required hints in the tcp_congestion_ops are information
for the user of this interface to signalize its importance when
implementing these functions.
However, cong_avoid comment incorrectly tells that it is required,
in reality congestion control must provide one of either cong_avoid or
cong_control.
In addition, min_tso_segs has not had any comment optional/required
hints. So mark it as optional since it is used only in BBR.
Co-developed-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Daniel Sedlak <daniel.sedlak@cdn77.com>
Link: https://patch.msgid.link/20260105115533.1151442-1-daniel.sedlak@cdn77.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Since commit 54a378f434 ("tcp: add the ability to control
max RTO"), TFO SYN+ACK RTO is capped by the TFO full sk's
inet_csk(sk)->icsk_rto_max.
The value is inherited from the parent listener.
Let's apply the same cap to non-TFO SYN+ACK.
Note that req->rsk_listener is always non-NULL when we call
tcp_reqsk_timeout() in reqsk_timer_handler() or tcp_check_req().
It could be NULL for SYN cookie req, but we do not use
req->timeout then.
Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20251106003357.273403-6-kuniyu@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
reqsk_timeout() is always called with @timeout being TCP_RTO_MAX.
Let's remove the arg.
As a prep for the next patch, reqsk_timeout() is moved to tcp.h
and renamed to tcp_reqsk_timeout().
Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20251106003357.273403-5-kuniyu@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Convert struct proto pre_connect(), connect(), bind(), and bind_add()
callback function prototypes from struct sockaddr to struct sockaddr_unsized.
This does not change per-implementation use of sockaddr for passing around
an arbitrarily sized sockaddr struct. Those will be addressed in future
patches.
Additionally removes the no longer referenced struct sockaddr from
include/net/inet_common.h.
No binary changes expected.
Signed-off-by: Kees Cook <kees@kernel.org>
Link: https://patch.msgid.link/20251104002617.2752303-5-kees@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This patch has no functional change, and prepares the following one.
tcp_rcvbuf_grow() will need to have access to tp->rcvq_space.space
old and new values.
Change mptcp_rcvbuf_grow() in a similar way.
Signed-off-by: Eric Dumazet <edumazet@google.com>
[ Moved 'oldval' declaration to the next patch to avoid warnings at
build time. ]
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Reviewed-by: Neal Cardwell <ncardwell@google.com>
Link: https://patch.msgid.link/20251028-net-tcp-recv-autotune-v3-3-74b43ba4c84c@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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Merge tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next
Martin KaFai Lau says:
====================
pull-request: bpf-next 2025-10-16
We've added 6 non-merge commits during the last 1 day(s) which contain
a total of 18 files changed, 577 insertions(+), 38 deletions(-).
The main changes are:
1) Bypass the global per-protocol memory accounting either by setting
a netns sysctl or using bpf_setsockopt in a bpf program,
from Kuniyuki Iwashima.
* tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next:
selftests/bpf: Add test for sk->sk_bypass_prot_mem.
bpf: Introduce SK_BPF_BYPASS_PROT_MEM.
bpf: Support bpf_setsockopt() for BPF_CGROUP_INET_SOCK_CREATE.
net: Introduce net.core.bypass_prot_mem sysctl.
net: Allow opt-out from global protocol memory accounting.
tcp: Save lock_sock() for memcg in inet_csk_accept().
====================
Link: https://patch.msgid.link/20251016204539.773707-1-martin.lau@linux.dev
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Make tcp-md5 use the MD5 library API (added in 6.18) instead of the
crypto_ahash API. This is much simpler and also more efficient:
- The library API just operates on struct md5_ctx. Just allocate this
struct on the stack instead of using a pool of pre-allocated
crypto_ahash and ahash_request objects.
- The library API accepts standard pointers and doesn't require
scatterlists. So, for hashing the headers just use an on-stack buffer
instead of a pool of pre-allocated kmalloc'ed scratch buffers.
- The library API never fails. Therefore, checking for MD5 hashing
errors is no longer necessary. Update tcp_v4_md5_hash_skb(),
tcp_v6_md5_hash_skb(), tcp_v4_md5_hash_hdr(), tcp_v6_md5_hash_hdr(),
tcp_md5_hash_key(), tcp_sock_af_ops::calc_md5_hash, and
tcp_request_sock_ops::calc_md5_hash to return void instead of int.
- The library API provides direct access to the MD5 code, eliminating
unnecessary overhead such as indirect function calls and scatterlist
management. Microbenchmarks of tcp_v4_md5_hash_skb() on x86_64 show a
speedup from 7518 to 7041 cycles (6% fewer) with skb->len == 1440, or
from 1020 to 678 cycles (33% fewer) with skb->len == 140.
Since tcp_sigpool_hash_skb_data() can no longer be used, add a function
tcp_md5_hash_skb_data() which is specialized to MD5. Of course, to the
extent that this duplicates any code, it's well worth it.
To preserve the existing behavior of TCP-MD5 support being disabled when
the kernel is booted with "fips=1", make tcp_md5_do_add() check
fips_enabled itself. Previously it relied on the error from
crypto_alloc_ahash("md5") being bubbled up. I don't know for sure that
this is actually needed, but this preserves the existing behavior.
Tested with bidirectional TCP-MD5, both IPv4 and IPv6, between a kernel
that includes this commit and a kernel that doesn't include this commit.
(Side note: please don't use TCP-MD5! It's cryptographically weak. But
as long as Linux supports it, it might as well be implemented properly.)
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Link: https://patch.msgid.link/20251014215836.115616-1-ebiggers@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Some protocols (e.g., TCP, UDP) implement memory accounting for socket
buffers and charge memory to per-protocol global counters pointed to by
sk->sk_proto->memory_allocated.
Sometimes, system processes do not want that limitation. For a similar
purpose, there is SO_RESERVE_MEM for sockets under memcg.
Also, by opting out of the per-protocol accounting, sockets under memcg
can avoid paying costs for two orthogonal memory accounting mechanisms.
A microbenchmark result is in the subsequent bpf patch.
Let's allow opt-out from the per-protocol memory accounting if
sk->sk_bypass_prot_mem is true.
sk->sk_bypass_prot_mem and sk->sk_prot are placed in the same cache
line, and sk_has_account() always fetches sk->sk_prot before accessing
sk->sk_bypass_prot_mem, so there is no extra cache miss for this patch.
The following patches will set sk->sk_bypass_prot_mem to true, and
then, the per-protocol memory accounting will be skipped.
Note that this does NOT disable memcg, but rather the per-protocol one.
Another option not to use the hole in struct sock_common is create
sk_prot variants like tcp_prot_bypass, but this would complicate
SOCKMAP logic, tcp_bpf_prots etc.
Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Reviewed-by: Shakeel Butt <shakeel.butt@linux.dev>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Acked-by: Roman Gushchin <roman.gushchin@linux.dev>
Link: https://patch.msgid.link/20251014235604.3057003-3-kuniyu@google.com
