sctp: update hb timer immediately after users change hb_interval

[ Upstream commit 1f4e803 ]

Currently, when hb_interval is changed by users, it won't take effect
until the next expiry of hb timer. As the default value is 30s, users
have to wait up to 30s to wait its hb_interval update to work.

This becomes pretty bad in containers where a much smaller value is
usually set on hb_interval. This patch improves it by resetting the
hb timer immediately once the value of hb_interval is updated by users.

Note that we don't address the already existing 'problem' when sending
a heartbeat 'on demand' if one hb has just been sent(from the timer)
mentioned in:

  https://www.mail-archive.com/linux-kernel@vger.kernel.org/msg590224.html

Signed-off-by: Xin Long <lucien.xin@gmail.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Fixes: 1da177e ("Linux-2.6.12-rc2")
Link: https://lore.kernel.org/r/75465785f8ee5df2fb3acdca9b8fafdc18984098.1696172660.git.lucien.xin@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

net/sctp/socket.c

@@ -2449,6 +2449,7 @@ static int sctp_apply_peer_addr_params(struct sctp_paddrparams *params,
 			if (trans) {
 				trans->hbinterval =
 				    msecs_to_jiffies(params->spp_hbinterval);
+				sctp_transport_reset_hb_timer(trans);
 			} else if (asoc) {
 				asoc->hbinterval =
 				    msecs_to_jiffies(params->spp_hbinterval);