From: Cambda Zhu cambda@linux.alibaba.com
[ Upstream commit f0628c524fd188c3f9418e12478dfdfadacba815 ]
This patch changes the behavior of TCP_LINGER2 about its limit. The sysctl_tcp_fin_timeout used to be the limit of TCP_LINGER2 but now it's only the default value. A new macro named TCP_FIN_TIMEOUT_MAX is added as the limit of TCP_LINGER2, which is 2 minutes.
Since TCP_LINGER2 used sysctl_tcp_fin_timeout as the default value and the limit in the past, the system administrator cannot set the default value for most of sockets and let some sockets have a greater timeout. It might be a mistake that let the sysctl to be the limit of the TCP_LINGER2. Maybe we can add a new sysctl to set the max of TCP_LINGER2, but FIN-WAIT-2 timeout is usually no need to be too long and 2 minutes are legal considering TCP specs.
Changes in v3: - Remove the new socket option and change the TCP_LINGER2 behavior so that the timeout can be set to value between sysctl_tcp_fin_timeout and 2 minutes.
Changes in v2: - Add int overflow check for the new socket option.
Changes in v1: - Add a new socket option to set timeout greater than sysctl_tcp_fin_timeout.
Signed-off-by: Cambda Zhu cambda@linux.alibaba.com Signed-off-by: David S. Miller davem@davemloft.net Stable-dep-of: 9df5335ca974 ("tcp: annotate data-races around tp->linger2") Signed-off-by: Sasha Levin sashal@kernel.org --- include/net/tcp.h | 1 + net/ipv4/tcp.c | 4 ++-- 2 files changed, 3 insertions(+), 2 deletions(-)
diff --git a/include/net/tcp.h b/include/net/tcp.h index 077feeca6c99e..2f456bed33ec3 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -125,6 +125,7 @@ void tcp_time_wait(struct sock *sk, int state, int timeo); * to combine FIN-WAIT-2 timeout with * TIME-WAIT timer. */ +#define TCP_FIN_TIMEOUT_MAX (120 * HZ) /* max TCP_LINGER2 value (two minutes) */
#define TCP_DELACK_MAX ((unsigned)(HZ/5)) /* maximal time to delay before sending an ACK */ #if HZ >= 100 diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index e33abcff56080..c6c73b9407098 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -3067,8 +3067,8 @@ static int do_tcp_setsockopt(struct sock *sk, int level, case TCP_LINGER2: if (val < 0) tp->linger2 = -1; - else if (val > net->ipv4.sysctl_tcp_fin_timeout / HZ) - tp->linger2 = 0; + else if (val > TCP_FIN_TIMEOUT_MAX / HZ) + tp->linger2 = TCP_FIN_TIMEOUT_MAX; else tp->linger2 = val * HZ; break;