| Message ID | 20230527040317.68247-1-cambda@linux.alibaba.com (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 34dfde4ad87b84d21278a7e19d92b5b2c68e6c4d |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [net,v3] tcp: Return user_mss for TCP_MAXSEG in CLOSE/LISTEN state if user_mss set | expand |
On Sat, May 27, 2023 at 6:04 AM Cambda Zhu <cambda@linux.alibaba.com> wrote: > > This patch replaces the tp->mss_cache check in getting TCP_MAXSEG > with tp->rx_opt.user_mss check for CLOSE/LISTEN sock. Since > tp->mss_cache is initialized with TCP_MSS_DEFAULT, checking if > it's zero is probably a bug. > > With this change, getting TCP_MAXSEG before connecting will return > default MSS normally, and return user_mss if user_mss is set. > > Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") > Reported-by: Jack Yang <mingliang@linux.alibaba.com> > Suggested-by: Eric Dumazet <edumazet@google.com> > Link: https://lore.kernel.org/netdev/CANn89i+3kL9pYtkxkwxwNMzvC_w3LNUum_2=3u+UyLBmGmifHA@mail.gmail.com/#t > Signed-off-by: Cambda Zhu <cambda@linux.alibaba.com> > Link: https://lore.kernel.org/netdev/14D45862-36EA-4076-974C-EA67513C92F6@linux.alibaba.com/ > Reviewed-by: Jason Xing <kerneljasonxing@gmail.com> > --- Reviewed-by: Eric Dumazet <edumazet@google.com>
Hello: This patch was applied to netdev/net.git (main) by Jakub Kicinski <kuba@kernel.org>: On Sat, 27 May 2023 12:03:17 +0800 you wrote: > This patch replaces the tp->mss_cache check in getting TCP_MAXSEG > with tp->rx_opt.user_mss check for CLOSE/LISTEN sock. Since > tp->mss_cache is initialized with TCP_MSS_DEFAULT, checking if > it's zero is probably a bug. > > With this change, getting TCP_MAXSEG before connecting will return > default MSS normally, and return user_mss if user_mss is set. > > [...] Here is the summary with links: - [net,v3] tcp: Return user_mss for TCP_MAXSEG in CLOSE/LISTEN state if user_mss set https://git.kernel.org/netdev/net/c/34dfde4ad87b You are awesome, thank you!
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index 4d6392c16b7a..3e01a58724b8 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -4081,7 +4081,8 @@ int do_tcp_getsockopt(struct sock *sk, int level, switch (optname) { case TCP_MAXSEG: val = tp->mss_cache; - if (!val && ((1 << sk->sk_state) & (TCPF_CLOSE | TCPF_LISTEN))) + if (tp->rx_opt.user_mss && + ((1 << sk->sk_state) & (TCPF_CLOSE | TCPF_LISTEN))) val = tp->rx_opt.user_mss; if (tp->repair) val = tp->rx_opt.mss_clamp;
This patch replaces the tp->mss_cache check in getting TCP_MAXSEG with tp->rx_opt.user_mss check for CLOSE/LISTEN sock. Since tp->mss_cache is initialized with TCP_MSS_DEFAULT, checking if it's zero is probably a bug. With this change, getting TCP_MAXSEG before connecting will return default MSS normally, and return user_mss if user_mss is set. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Reported-by: Jack Yang <mingliang@linux.alibaba.com> Suggested-by: Eric Dumazet <edumazet@google.com> Link: https://lore.kernel.org/netdev/CANn89i+3kL9pYtkxkwxwNMzvC_w3LNUum_2=3u+UyLBmGmifHA@mail.gmail.com/#t Signed-off-by: Cambda Zhu <cambda@linux.alibaba.com> Link: https://lore.kernel.org/netdev/14D45862-36EA-4076-974C-EA67513C92F6@linux.alibaba.com/ Reviewed-by: Jason Xing <kerneljasonxing@gmail.com> --- v3: - Add CC maintainers. v2: - Update Fixes tag with commit in current tree. - Add Jason's Reviewed-by tag. v1: - Return default MSS if user_mss not set for backwards compatibility. - Send patch to net instead of net-next, with Fixes tag. - Add Eric's tags. --- net/ipv4/tcp.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)