mirror of
https://mirrors.bfsu.edu.cn/git/linux.git
synced 2024-11-25 13:14:07 +08:00
4057037535
We had various bugs over the years with code
breaking the assumption that tp->snd_cwnd is greater
than zero.
Lately, syzbot reported the WARN_ON_ONCE(!tp->prior_cwnd) added
in commit 8b8a321ff7 ("tcp: fix zero cwnd in tcp_cwnd_reduction")
can trigger, and without a repro we would have to spend
considerable time finding the bug.
Instead of complaining too late, we want to catch where
and when tp->snd_cwnd is set to an illegal value.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Suggested-by: Yuchung Cheng <ycheng@google.com>
Cc: Neal Cardwell <ncardwell@google.com>
Acked-by: Yuchung Cheng <ycheng@google.com>
Link: https://lore.kernel.org/r/20220405233538.947344-1-eric.dumazet@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
66 lines
1.4 KiB
C
66 lines
1.4 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
|
|
/* Tom Kelly's Scalable TCP
|
|
*
|
|
* See http://www.deneholme.net/tom/scalable/
|
|
*
|
|
* John Heffner <jheffner@sc.edu>
|
|
*/
|
|
|
|
#include <linux/module.h>
|
|
#include <net/tcp.h>
|
|
|
|
/* 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");
|