* [PATCH 6.12.y 1/2] tcp: introduce icsk->icsk_keepalive_timer
2026-09-16 16:34 FAILED: patch "[PATCH] mptcp: prevent race between disconnect() and rtx" failed to apply to 6.12-stable tree gregkh
@ 2026-09-17 3:53 ` Sasha Levin
2026-09-17 3:53 ` [PATCH 6.12.y 2/2] mptcp: prevent race between disconnect() and rtx Sasha Levin
0 siblings, 1 reply; 3+ messages in thread
From: Sasha Levin @ 2026-09-17 3:53 UTC (permalink / raw)
To: stable; +Cc: Eric Dumazet, Kuniyuki Iwashima, Jakub Kicinski, Sasha Levin
From: Eric Dumazet <edumazet@google.com>
[ Upstream commit 08dfe370239e53494453cee1e2ded2cdaa1efd12 ]
sk->sk_timer has been used for TCP keepalives.
Keepalive timers are not in fast path, we want to use sk->sk_timer
storage for retransmit timers, for better cache locality.
Create icsk->icsk_keepalive_timer and change keepalive
code to no longer use sk->sk_timer.
Added space is reclaimed in the following patch.
This includes changes to MPTCP, which was also using sk_timer.
Alias icsk->mptcp_tout_timer and icsk->icsk_keepalive_timer
for inet_sk_diag_fill() sake.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com>
Link: https://patch.msgid.link/20251124175013.1473655-4-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
[6.12 dependency adaptation for 85c580b0d859:
Keep the 6.12 from_timer(), icsk_timeout and existing inet_csk keepalive
helpers. Move those helpers and the DCCP keepalive callback to the new
timer as well; DCCP still shares inet_csk_init_xmit_timers() in this tree.
Preserve the stable cacheline documentation format and retransmit fields.
Include only the MPTCP retransmit-timer migration from 9a5e5334adc03:
alias sk_timer as mptcp_retransmit_timer and update its initialization,
callback, pending checks, reset and stop operations. TCP and DCCP keep
their existing icsk_retransmit_timer.
Use the existing mptcp_pm_connection_closed() helper for close events,
following 5add80bfdc46f, so the target's disconnect hunk applies unchanged.
Initialize MPTCP's icsk_rto_min to the stable TCP_RTO_MIN default, since
the target reads it but MPTCP does not call tcp_init_sock().
No functions are added. The synchronous-stop fix remains in the target.]
Stable-dep-of: 85c580b0d859 ("mptcp: prevent race between disconnect() and rtx")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
.../net_cachelines/inet_connection_sock.rst | 1 +
include/net/inet_connection_sock.h | 11 +++++--
include/net/sock.h | 6 +++-
net/dccp/timer.c | 4 ++-
net/ipv4/inet_connection_sock.c | 10 +++---
net/ipv4/inet_diag.c | 4 +--
net/ipv4/tcp_ipv4.c | 4 +--
net/ipv4/tcp_timer.c | 5 +--
net/ipv6/tcp_ipv6.c | 4 +--
net/mptcp/pm.c | 3 ++
net/mptcp/protocol.c | 33 ++++++++-----------
net/mptcp/protocol.h | 2 +-
.../selftests/bpf/progs/bpf_iter_tcp4.c | 4 +--
.../selftests/bpf/progs/bpf_iter_tcp6.c | 4 +--
14 files changed, 54 insertions(+), 41 deletions(-)
diff --git a/Documentation/networking/net_cachelines/inet_connection_sock.rst b/Documentation/networking/net_cachelines/inet_connection_sock.rst
index 7a911dc95652e..9a5289462f1e4 100644
--- a/Documentation/networking/net_cachelines/inet_connection_sock.rst
+++ b/Documentation/networking/net_cachelines/inet_connection_sock.rst
@@ -14,6 +14,7 @@ struct_inet_bind2_bucket icsk_bind2_hash read_mostly -
unsigned_long icsk_timeout read_mostly - inet_csk_reset_xmit_timer,tcp_connect
struct_timer_list icsk_retransmit_timer read_mostly - inet_csk_reset_xmit_timer,tcp_connect
struct_timer_list icsk_delack_timer read_mostly - inet_csk_reset_xmit_timer,tcp_connect
+struct_timer_list icsk_keepalive_timer - -
u32 icsk_rto read_write - tcp_cwnd_validate,tcp_schedule_loss_probe,tcp_connect_init,tcp_connect,tcp_write_xmit,tcp_push_one
u32 icsk_rto_min - -
u32 icsk_delack_max - -
diff --git a/include/net/inet_connection_sock.h b/include/net/inet_connection_sock.h
index 41354036b0c87..e898cee3dff6e 100644
--- a/include/net/inet_connection_sock.h
+++ b/include/net/inet_connection_sock.h
@@ -62,6 +62,9 @@ struct inet_connection_sock_af_ops {
* @icsk_bind2_hash: Bind node in the bhash2 table
* @icsk_timeout: Timeout
* @icsk_retransmit_timer: Resend (no ack)
+ * @icsk_delack_timer: Delayed ACK timer
+ * @icsk_keepalive_timer: Keepalive timer
+ * @mptcp_tout_timer: MPTCP timeout timer
* @icsk_rto: Retransmit timeout
* @icsk_pmtu_cookie Last pmtu seen by socket
* @icsk_ca_ops Pluggable congestion control hook
@@ -88,8 +91,12 @@ struct inet_connection_sock {
struct inet_bind_bucket *icsk_bind_hash;
struct inet_bind2_bucket *icsk_bind2_hash;
unsigned long icsk_timeout;
- struct timer_list icsk_retransmit_timer;
- struct timer_list icsk_delack_timer;
+ struct timer_list icsk_retransmit_timer;
+ struct timer_list icsk_delack_timer;
+ union {
+ struct timer_list icsk_keepalive_timer;
+ struct timer_list mptcp_tout_timer;
+ };
__u32 icsk_rto;
__u32 icsk_rto_min;
__u32 icsk_delack_max;
diff --git a/include/net/sock.h b/include/net/sock.h
index dffbaaa7fe493..416d96f443246 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -300,6 +300,7 @@ struct sk_filter;
* @sk_txrehash: enable TX hash rethink
* @sk_filter: socket filtering instructions
* @sk_timer: sock cleanup timer
+ * @mptcp_retransmit_timer: MPTCP retransmit timer
* @sk_stamp: time stamp of last packet received
* @sk_stamp_seq: lock for accessing sk_stamp on 32 bit architectures only
* @sk_tsflags: SO_TIMESTAMPING flags
@@ -465,7 +466,10 @@ struct sock {
u32 sk_dst_pending_confirm;
u32 sk_pacing_status; /* see enum sk_pacing */
struct page_frag sk_frag;
- struct timer_list sk_timer;
+ union {
+ struct timer_list sk_timer;
+ struct timer_list mptcp_retransmit_timer;
+ };
unsigned long sk_pacing_rate; /* bytes per second */
atomic_t sk_zckey;
diff --git a/net/dccp/timer.c b/net/dccp/timer.c
index a4cfb47b60e52..fc1d88d6bc3fb 100644
--- a/net/dccp/timer.c
+++ b/net/dccp/timer.c
@@ -160,7 +160,9 @@ static void dccp_write_timer(struct timer_list *t)
static void dccp_keepalive_timer(struct timer_list *t)
{
- struct sock *sk = from_timer(sk, t, sk_timer);
+ struct inet_connection_sock *icsk =
+ from_timer(icsk, t, icsk_keepalive_timer);
+ struct sock *sk = &icsk->icsk_inet.sk;
pr_err("dccp should not use a keepalive timer !\n");
sock_put(sk);
diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c
index 117a424d1fee3..18e95dd367843 100644
--- a/net/ipv4/inet_connection_sock.c
+++ b/net/ipv4/inet_connection_sock.c
@@ -750,7 +750,7 @@ void inet_csk_init_xmit_timers(struct sock *sk,
timer_setup(&icsk->icsk_retransmit_timer, retransmit_handler, 0);
timer_setup(&icsk->icsk_delack_timer, delack_handler, 0);
- timer_setup(&sk->sk_timer, keepalive_handler, 0);
+ timer_setup(&icsk->icsk_keepalive_timer, keepalive_handler, 0);
icsk->icsk_pending = icsk->icsk_ack.pending = 0;
}
EXPORT_SYMBOL(inet_csk_init_xmit_timers);
@@ -763,7 +763,7 @@ void inet_csk_clear_xmit_timers(struct sock *sk)
sk_stop_timer(sk, &icsk->icsk_retransmit_timer);
sk_stop_timer(sk, &icsk->icsk_delack_timer);
- sk_stop_timer(sk, &sk->sk_timer);
+ sk_stop_timer(sk, &icsk->icsk_keepalive_timer);
}
EXPORT_SYMBOL(inet_csk_clear_xmit_timers);
@@ -778,18 +778,18 @@ void inet_csk_clear_xmit_timers_sync(struct sock *sk)
sk_stop_timer_sync(sk, &icsk->icsk_retransmit_timer);
sk_stop_timer_sync(sk, &icsk->icsk_delack_timer);
- sk_stop_timer_sync(sk, &sk->sk_timer);
+ sk_stop_timer_sync(sk, &icsk->icsk_keepalive_timer);
}
void inet_csk_delete_keepalive_timer(struct sock *sk)
{
- sk_stop_timer(sk, &sk->sk_timer);
+ sk_stop_timer(sk, &inet_csk(sk)->icsk_keepalive_timer);
}
EXPORT_SYMBOL(inet_csk_delete_keepalive_timer);
void inet_csk_reset_keepalive_timer(struct sock *sk, unsigned long len)
{
- sk_reset_timer(sk, &sk->sk_timer, jiffies + len);
+ sk_reset_timer(sk, &inet_csk(sk)->icsk_keepalive_timer, jiffies + len);
}
EXPORT_SYMBOL(inet_csk_reset_keepalive_timer);
diff --git a/net/ipv4/inet_diag.c b/net/ipv4/inet_diag.c
index f2de2f2962595..01b6b50ae11d4 100644
--- a/net/ipv4/inet_diag.c
+++ b/net/ipv4/inet_diag.c
@@ -319,11 +319,11 @@ int inet_sk_diag_fill(struct sock *sk, struct inet_connection_sock *icsk,
r->idiag_retrans = icsk->icsk_probes_out;
r->idiag_expires =
jiffies_delta_to_msecs(icsk->icsk_timeout - jiffies);
- } else if (timer_pending(&sk->sk_timer)) {
+ } else if (timer_pending(&icsk->icsk_keepalive_timer)) {
r->idiag_timer = 2;
r->idiag_retrans = icsk->icsk_probes_out;
r->idiag_expires =
- jiffies_delta_to_msecs(sk->sk_timer.expires - jiffies);
+ jiffies_delta_to_msecs(icsk->icsk_keepalive_timer.expires - jiffies);
}
if ((ext & (1 << (INET_DIAG_INFO - 1))) && handler->idiag_info_size) {
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 2b7c580e37281..36862681731f2 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -2919,9 +2919,9 @@ static void get_tcp4_sock(struct sock *sk, struct seq_file *f, int i)
} else if (icsk->icsk_pending == ICSK_TIME_PROBE0) {
timer_active = 4;
timer_expires = icsk->icsk_timeout;
- } else if (timer_pending(&sk->sk_timer)) {
+ } else if (timer_pending(&icsk->icsk_keepalive_timer)) {
timer_active = 2;
- timer_expires = sk->sk_timer.expires;
+ timer_expires = icsk->icsk_keepalive_timer.expires;
} else {
timer_active = 0;
timer_expires = jiffies;
diff --git a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c
index a58094b0acd4f..566e4bf1b5eff 100644
--- a/net/ipv4/tcp_timer.c
+++ b/net/ipv4/tcp_timer.c
@@ -755,8 +755,9 @@ EXPORT_IPV6_MOD_GPL(tcp_set_keepalive);
static void tcp_keepalive_timer (struct timer_list *t)
{
- struct sock *sk = from_timer(sk, t, sk_timer);
- struct inet_connection_sock *icsk = inet_csk(sk);
+ struct inet_connection_sock *icsk =
+ from_timer(icsk, t, icsk_keepalive_timer);
+ struct sock *sk = &icsk->icsk_inet.sk;
struct tcp_sock *tp = tcp_sk(sk);
u32 elapsed;
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 84efaf846f07f..c8c6b7625e6d4 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -2177,9 +2177,9 @@ static void get_tcp6_sock(struct seq_file *seq, struct sock *sp, int i)
} else if (icsk->icsk_pending == ICSK_TIME_PROBE0) {
timer_active = 4;
timer_expires = icsk->icsk_timeout;
- } else if (timer_pending(&sp->sk_timer)) {
+ } else if (timer_pending(&icsk->icsk_keepalive_timer)) {
timer_active = 2;
- timer_expires = sp->sk_timer.expires;
+ timer_expires = icsk->icsk_keepalive_timer.expires;
} else {
timer_active = 0;
timer_expires = jiffies;
diff --git a/net/mptcp/pm.c b/net/mptcp/pm.c
index 009020ee1e041..f6968833f83d0 100644
--- a/net/mptcp/pm.c
+++ b/net/mptcp/pm.c
@@ -154,6 +154,9 @@ void mptcp_pm_fully_established(struct mptcp_sock *msk, const struct sock *ssk)
void mptcp_pm_connection_closed(struct mptcp_sock *msk)
{
pr_debug("msk=%p\n", msk);
+
+ if (msk->token)
+ mptcp_event(MPTCP_EVENT_CLOSED, msk, NULL, GFP_KERNEL);
}
void mptcp_pm_subflow_established(struct mptcp_sock *msk)
diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index 8b61fe656ec66..a84b635d8ccbf 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -414,9 +414,7 @@ static bool __mptcp_move_skb(struct sock *sk, struct sk_buff *skb)
static void mptcp_stop_rtx_timer(struct sock *sk)
{
- struct inet_connection_sock *icsk = inet_csk(sk);
-
- sk_stop_timer(sk, &icsk->icsk_retransmit_timer);
+ sk_stop_timer(sk, &sk->mptcp_retransmit_timer);
mptcp_sk(sk)->timer_ival = 0;
}
@@ -973,12 +971,11 @@ static void __mptcp_flush_join_list(struct sock *sk, struct list_head *join_list
static bool mptcp_rtx_timer_pending(struct sock *sk)
{
- return timer_pending(&inet_csk(sk)->icsk_retransmit_timer);
+ return timer_pending(&sk->mptcp_retransmit_timer);
}
static void mptcp_reset_rtx_timer(struct sock *sk)
{
- struct inet_connection_sock *icsk = inet_csk(sk);
unsigned long tout;
/* prevent rescheduling on close */
@@ -986,7 +983,7 @@ static void mptcp_reset_rtx_timer(struct sock *sk)
return;
tout = mptcp_sk(sk)->timer_ival;
- sk_reset_timer(sk, &icsk->icsk_retransmit_timer, jiffies + tout);
+ sk_reset_timer(sk, &sk->mptcp_retransmit_timer, jiffies + tout);
}
bool mptcp_schedule_work(struct sock *sk)
@@ -2390,9 +2387,7 @@ static int mptcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
static void mptcp_retransmit_timer(struct timer_list *t)
{
- struct inet_connection_sock *icsk = from_timer(icsk, t,
- icsk_retransmit_timer);
- struct sock *sk = &icsk->icsk_inet.sk;
+ struct sock *sk = from_timer(sk, t, mptcp_retransmit_timer);
struct mptcp_sock *msk = mptcp_sk(sk);
bh_lock_sock(sk);
@@ -2410,7 +2405,9 @@ static void mptcp_retransmit_timer(struct timer_list *t)
static void mptcp_tout_timer(struct timer_list *t)
{
- struct sock *sk = from_timer(sk, t, sk_timer);
+ struct inet_connection_sock *icsk =
+ from_timer(icsk, t, mptcp_tout_timer);
+ struct sock *sk = &icsk->icsk_inet.sk;
mptcp_schedule_work(sk);
sock_put(sk);
@@ -2853,7 +2850,7 @@ void mptcp_reset_tout_timer(struct mptcp_sock *msk, unsigned long fail_tout)
*/
timeout = inet_csk(sk)->icsk_mtup.probe_timestamp ? close_timeout : fail_tout;
- sk_reset_timer(sk, &sk->sk_timer, timeout);
+ sk_reset_timer(sk, &inet_csk(sk)->mptcp_tout_timer, timeout);
}
static void mptcp_mp_fail_no_response(struct mptcp_sock *msk)
@@ -2969,6 +2966,7 @@ static void __mptcp_init_sock(struct sock *sk)
msk->first_pending = NULL;
WRITE_ONCE(msk->rmem_fwd_alloc, 0);
WRITE_ONCE(msk->rmem_released, 0);
+ inet_csk(sk)->icsk_rto_min = TCP_RTO_MIN;
msk->timer_ival = TCP_RTO_MIN;
msk->scaling_ratio = TCP_DEFAULT_SCALING_RATIO;
@@ -2986,9 +2984,8 @@ static void __mptcp_init_sock(struct sock *sk)
mptcp_pm_data_init(msk);
spin_lock_init(&msk->fallback_lock);
- /* re-use the csk retrans timer for MPTCP-level retrans */
- timer_setup(&msk->sk.icsk_retransmit_timer, mptcp_retransmit_timer, 0);
- timer_setup(&sk->sk_timer, mptcp_tout_timer, 0);
+ timer_setup(&sk->mptcp_retransmit_timer, mptcp_retransmit_timer, 0);
+ timer_setup(&msk->sk.mptcp_tout_timer, mptcp_tout_timer, 0);
}
static void mptcp_ca_reset(struct sock *sk)
@@ -3190,7 +3187,7 @@ static void __mptcp_destroy_sock(struct sock *sk)
might_sleep();
mptcp_stop_rtx_timer(sk);
- sk_stop_timer(sk, &sk->sk_timer);
+ sk_stop_timer(sk, &inet_csk(sk)->mptcp_tout_timer);
msk->pm.status = 0;
mptcp_release_sched(msk);
@@ -3295,8 +3292,7 @@ bool __mptcp_close(struct sock *sk, long timeout)
sock_hold(sk);
pr_debug("msk=%p state=%d\n", sk, sk->sk_state);
- if (msk->token)
- mptcp_event(MPTCP_EVENT_CLOSED, msk, NULL, GFP_KERNEL);
+ mptcp_pm_connection_closed(msk);
if (sk->sk_state == TCP_CLOSE) {
__mptcp_destroy_sock(sk);
@@ -3362,8 +3358,7 @@ static int mptcp_disconnect(struct sock *sk, int flags)
mptcp_stop_rtx_timer(sk);
mptcp_stop_tout_timer(sk);
- if (msk->token)
- mptcp_event(MPTCP_EVENT_CLOSED, msk, NULL, GFP_KERNEL);
+ mptcp_pm_connection_closed(msk);
/* msk->subflow is still intact, the following will not free the first
* subflow
diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
index 36f3f5b34a5d6..c1accd3dc6bfa 100644
--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h
@@ -844,7 +844,7 @@ static inline void mptcp_stop_tout_timer(struct sock *sk)
if (!inet_csk(sk)->icsk_mtup.probe_timestamp)
return;
- sk_stop_timer(sk, &sk->sk_timer);
+ sk_stop_timer(sk, &inet_csk(sk)->mptcp_tout_timer);
inet_csk(sk)->icsk_mtup.probe_timestamp = 0;
}
diff --git a/tools/testing/selftests/bpf/progs/bpf_iter_tcp4.c b/tools/testing/selftests/bpf/progs/bpf_iter_tcp4.c
index 92267abb462fc..be540970fcc1f 100644
--- a/tools/testing/selftests/bpf/progs/bpf_iter_tcp4.c
+++ b/tools/testing/selftests/bpf/progs/bpf_iter_tcp4.c
@@ -103,9 +103,9 @@ static int dump_tcp_sock(struct seq_file *seq, struct tcp_sock *tp,
} else if (icsk->icsk_pending == ICSK_TIME_PROBE0) {
timer_active = 4;
timer_expires = icsk->icsk_timeout;
- } else if (timer_pending(&sp->sk_timer)) {
+ } else if (timer_pending(&icsk->icsk_keepalive_timer)) {
timer_active = 2;
- timer_expires = sp->sk_timer.expires;
+ timer_expires = icsk->icsk_keepalive_timer.expires;
} else {
timer_active = 0;
timer_expires = bpf_jiffies64();
diff --git a/tools/testing/selftests/bpf/progs/bpf_iter_tcp6.c b/tools/testing/selftests/bpf/progs/bpf_iter_tcp6.c
index 943f7bba180e7..9f72398fc3cc3 100644
--- a/tools/testing/selftests/bpf/progs/bpf_iter_tcp6.c
+++ b/tools/testing/selftests/bpf/progs/bpf_iter_tcp6.c
@@ -103,9 +103,9 @@ static int dump_tcp6_sock(struct seq_file *seq, struct tcp6_sock *tp,
} else if (icsk->icsk_pending == ICSK_TIME_PROBE0) {
timer_active = 4;
timer_expires = icsk->icsk_timeout;
- } else if (timer_pending(&sp->sk_timer)) {
+ } else if (timer_pending(&icsk->icsk_keepalive_timer)) {
timer_active = 2;
- timer_expires = sp->sk_timer.expires;
+ timer_expires = icsk->icsk_keepalive_timer.expires;
} else {
timer_active = 0;
timer_expires = bpf_jiffies64();
--
2.53.0
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