From: Serguei Smirnov <ssmirnov@whamcloud.com>
Date: Wed, 7 Oct 2020 22:51:06 +0000 (-0400)
Subject: LU-13892 lnet: lock-up during router check
X-Git-Tag: 2.12.6-RC1~25
X-Git-Url: https://git.whamcloud.com/?a=commitdiff_plain;h=refs%2Fchanges%2F72%2F40172%2F2;p=fs%2Flustre-release.git

LU-13892 lnet: lock-up during router check

This is a fix for the issue with LNet lock-up while waiting
for routers to become active with check_routers_before_use
option. Release ln_api_mutex while waiting to allow
incoming connections to be handled.

Signed-off-by: Serguei Smirnov <ssmirnov@whamcloud.com>
Change-Id: I63b1d1ce5ee2b27a3bd2cea78713fc6fc7502cf7
Reviewed-on: https://review.whamcloud.com/40172
Tested-by: jenkins <devops@whamcloud.com>
Reviewed-by: Olaf Faaland-LLNL <faaland1@llnl.gov>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Amir Shehata <ashehata@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>
---

diff --git a/lnet/lnet/router.c b/lnet/lnet/router.c
index 806cf8c..e2966cf 100644
--- a/lnet/lnet/router.c
+++ b/lnet/lnet/router.c
@@ -842,6 +842,7 @@ lnet_wait_known_routerstate(void)
 
 	LASSERT(the_lnet.ln_mt_state == LNET_MT_STATE_RUNNING);
 
+	/* the_lnet.ln_api_mutex must be locked */
 	for (;;) {
 		int cpt = lnet_net_lock_current();
 
@@ -865,8 +866,10 @@ lnet_wait_known_routerstate(void)
 		if (all_known)
 			return;
 
+		mutex_unlock(&the_lnet.ln_api_mutex);
 		set_current_state(TASK_UNINTERRUPTIBLE);
 		schedule_timeout(cfs_time_seconds(1));
+		mutex_lock(&the_lnet.ln_api_mutex);
 	}
 }