[Cluster-devel] [PATCH AUTOSEL 5.1 118/141] dlm: check if workqueues are NULL before flushing/destroying

[Sasha Levin]

From: David Windsor <dwind...@redhat.com>

[ Upstream commit b355516f450703c9015316e429b66a93dfff0e6f ]

If the DLM lowcomms stack is shut down before any DLM
traffic can be generated, flush_workqueue() and
destroy_workqueue() can be called on empty send and/or recv
workqueues.

Insert guard conditionals to only call flush_workqueue()
and destroy_workqueue() on workqueues that are not NULL.

Signed-off-by: David Windsor <dwind...@redhat.com>
Signed-off-by: David Teigland <teigl...@redhat.com>
Signed-off-by: Sasha Levin <sas...@kernel.org>
---
 fs/dlm/lowcomms.c | 18 ++++++++++++------
 1 file changed, 12 insertions(+), 6 deletions(-)

diff --git a/fs/dlm/lowcomms.c b/fs/dlm/lowcomms.c
index c98ad9777ad9..88d7ec76f669 100644
--- a/fs/dlm/lowcomms.c
+++ b/fs/dlm/lowcomms.c
@@ -1630,8 +1630,10 @@ static void clean_writequeues(void)
 
 static void work_stop(void)
 {
-       destroy_workqueue(recv_workqueue);
-       destroy_workqueue(send_workqueue);
+       if (recv_workqueue)
+               destroy_workqueue(recv_workqueue);
+       if (send_workqueue)
+               destroy_workqueue(send_workqueue);
 }
 
 static int work_start(void)
@@ -1691,13 +1693,17 @@ static void work_flush(void)
        struct hlist_node *n;
        struct connection *con;
 
-       flush_workqueue(recv_workqueue);
-       flush_workqueue(send_workqueue);
+       if (recv_workqueue)
+               flush_workqueue(recv_workqueue);
+       if (send_workqueue)
+               flush_workqueue(send_workqueue);
        do {
                ok = 1;
                foreach_conn(stop_conn);
-               flush_workqueue(recv_workqueue);
-               flush_workqueue(send_workqueue);
+               if (recv_workqueue)
+                       flush_workqueue(recv_workqueue);
+               if (send_workqueue)
+                       flush_workqueue(send_workqueue);
                for (i = 0; i < CONN_HASH_SIZE && ok; i++) {
                        hlist_for_each_entry_safe(con, n,
                                                  &connection_hash[i], list) {
-- 
2.20.1