From 3541f9e8bdebce02458882b66b638d7302c1f616 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Thu, 2 Feb 2017 08:04:56 -0800 Subject: tcp: add tcp_mss_clamp() helper Small cleanup factorizing code doing the TCP_MAXSEG clamping. Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller --- include/linux/tcp.h | 9 +++++++++ 1 file changed, 9 insertions(+) (limited to 'include/linux/tcp.h') diff --git a/include/linux/tcp.h b/include/linux/tcp.h index f88f4649ba6f..cfc2d9506ce8 100644 --- a/include/linux/tcp.h +++ b/include/linux/tcp.h @@ -445,4 +445,13 @@ static inline void tcp_saved_syn_free(struct tcp_sock *tp) struct sk_buff *tcp_get_timestamping_opt_stats(const struct sock *sk); +static inline u16 tcp_mss_clamp(const struct tcp_sock *tp, u16 mss) +{ + /* We use READ_ONCE() here because socket might not be locked. + * This happens for listeners. + */ + u16 user_mss = READ_ONCE(tp->rx_opt.user_mss); + + return (user_mss && user_mss < mss) ? user_mss : mss; +} #endif /* _LINUX_TCP_H */ -- cgit v1.2.3