[lvm-devel] [Git][lvmteam/lvm2][main] lvmlockd: client mutex ordering

[David Teigland (@teigland)]

David Teigland pushed to branch main at LVM team / lvm2


Commits:
c37416b6 by David Teigland at 2023-08-31T13:15:07-05:00
lvmlockd: client mutex ordering

Avoid deadlock between threads on mutexes (in theory.)

- - - - -


1 changed file:

- daemons/lvmlockd/lvmlockd-core.c


Changes:

=====================================
daemons/lvmlockd/lvmlockd-core.c
=====================================
@@ -4690,9 +4690,12 @@ static int dump_info(int *dump_len)
 
 	/*
 	 * clients
+	 * Proper lock order is client_mutex then cl->mutex,
+	 * but cl->mutex is already held so skip client info
+	 * if it would block.
 	 */
-
-	pthread_mutex_lock(&client_mutex);
+	if (pthread_mutex_trylock(&client_mutex))
+		goto print_ls;
 	list_for_each_entry(cl, &client_list, list) {
 		ret = print_client(cl, "client", pos, len);
 		if (ret >= len - pos) {
@@ -4706,6 +4709,7 @@ static int dump_info(int *dump_len)
 	if (rv < 0)
 		return rv;
 
+ print_ls:
 	/*
 	 * lockspaces with their action/resource/lock info
 	 */



View it on GitLab: https://gitlab.com/lvmteam/lvm2/-/commit/c37416b6aac10521fe4fdc26618eb476bba0bd2f

-- 
View it on GitLab: https://gitlab.com/lvmteam/lvm2/-/commit/c37416b6aac10521fe4fdc26618eb476bba0bd2f
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