This is a note to let you know that I've just added the patch titled
net: Replace the limit of TCP_LINGER2 with TCP_FIN_TIMEOUT_MAX
to the 4.19-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
net-replace-the-limit-of-tcp_linger2-with-tcp_fin_ti.patch
and it can be found in the queue-4.19 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit b1ff776eeefc168d9e591f6d3c7d58f3c7ac80f8
Author: Cambda Zhu <cambda@xxxxxxxxxxxxxxxxx>
Date: Fri Apr 24 16:06:16 2020 +0800
net: Replace the limit of TCP_LINGER2 with TCP_FIN_TIMEOUT_MAX
[ 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@xxxxxxxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Stable-dep-of: 9df5335ca974 ("tcp: annotate data-races around tp->linger2")
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/include/net/tcp.h b/include/net/tcp.h
index 81300a04b5808..22cca858f2678 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -128,6 +128,7 @@ 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 cb96775fc86f6..9f3cdcbbb7590 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -3001,8 +3001,8 @@ 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;
