Fix segfault with client/server and minimal output

Fixes: bf2921f02651
Reported-by: Ben England <bengland@redhat.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

1 files changed, 3 insertions, 0 deletions

diff --git a/diskutil.c b/diskutil.c
index 98ae2fe3..52d87f64 100644
--- a/diskutil.c
+++ b/diskutil.c
@@ -694,6 +694,9 @@ void show_disk_util(int terse, struct json_object *parent)
 	struct flist_head *entry;
 	struct disk_util *du;
 
+	if (!disk_util_mutex)
+		return;
+
 	fio_mutex_down(disk_util_mutex);
 
 	if (flist_empty(&disk_list)) {