From 4617721c502b2ddaa4e324e86da4997edf738fa5 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Wed, 2 Sep 2026 09:55:01 -0400 Subject: ftrace: Synchronize the initialization of ftrace_ops There's some internal state that ftrace_ops needs to have set, but since it can be declared outside of the ftrace.c code, it calls ftrace_ops_init() on the ops in every global function. The issue is that if two tasks call it on the same ops at the same time it is possible to have the initialization of one corrupt the initialization of the other call. Create a ops_mutex to use to synchronize every initialization of the ftrace_ops. The mutex is taken within checking the ftrace_ops flag that states it was initializied but the flag is checked again after the mutex has been taken. Checking first outside the mutex allows it to shortcut having to take the mutex. But then the check needs to be done again after the mute is taken in case of races. Cc: stable@vger.kernel.org Link: https://patch.msgid.link/20260902095501.6b59af20@gandalf.local.home Fixes: f04f24fb7e48d ("ftrace, kprobes: Fix a deadlock on ftrace_regex_lock") Reported-by: sashiko-bot@kernel.org Close: https://lore.kernel.org/all/20260829025528.49A831F000E9@smtp.kernel.org/ Signed-off-by: Steven Rostedt --- net/ipv4/tcp_scalable.c | 65 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 65 insertions(+) create mode 100644 net/ipv4/tcp_scalable.c (limited to 'net/ipv4/tcp_scalable.c') diff --git a/net/ipv4/tcp_scalable.c b/net/ipv4/tcp_scalable.c new file mode 100644 index 000000000..862b96248 --- /dev/null +++ b/net/ipv4/tcp_scalable.c @@ -0,0 +1,65 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* Tom Kelly's Scalable TCP + * + * See http://www.deneholme.net/tom/scalable/ + * + * John Heffner + */ + +#include +#include + +/* These factors derived from the recommended values in the aer: + * .01 and 7/8. + */ +#define TCP_SCALABLE_AI_CNT 100U +#define TCP_SCALABLE_MD_SCALE 3 + +static void tcp_scalable_cong_avoid(struct sock *sk, u32 ack, u32 acked) +{ + struct tcp_sock *tp = tcp_sk(sk); + + if (!tcp_is_cwnd_limited(sk)) + return; + + if (tcp_in_slow_start(tp)) { + acked = tcp_slow_start(tp, acked); + if (!acked) + return; + } + tcp_cong_avoid_ai(tp, min(tcp_snd_cwnd(tp), TCP_SCALABLE_AI_CNT), + acked); +} + +static u32 tcp_scalable_ssthresh(struct sock *sk) +{ + const struct tcp_sock *tp = tcp_sk(sk); + + return max(tcp_snd_cwnd(tp) - (tcp_snd_cwnd(tp)>>TCP_SCALABLE_MD_SCALE), 2U); +} + +static struct tcp_congestion_ops tcp_scalable __read_mostly = { + .ssthresh = tcp_scalable_ssthresh, + .undo_cwnd = tcp_reno_undo_cwnd, + .cong_avoid = tcp_scalable_cong_avoid, + + .owner = THIS_MODULE, + .name = "scalable", +}; + +static int __init tcp_scalable_register(void) +{ + return tcp_register_congestion_control(&tcp_scalable); +} + +static void __exit tcp_scalable_unregister(void) +{ + tcp_unregister_congestion_control(&tcp_scalable); +} + +module_init(tcp_scalable_register); +module_exit(tcp_scalable_unregister); + +MODULE_AUTHOR("John Heffner"); +MODULE_LICENSE("GPL"); +MODULE_DESCRIPTION("Scalable TCP"); -- cgit v1.3.1