s390/dasd: hold request queue sysfs lock when calling elevator_init()
authorHeiko Carstens <heiko.carstens@de.ibm.com>
Thu, 31 Oct 2013 12:24:28 +0000 (13:24 +0100)
committerJens Axboe <axboe@kernel.dk>
Fri, 8 Nov 2013 16:10:29 +0000 (09:10 -0700)
"elevator: Fix a race in elevator switching and md device initialization"
changed the semantics of elevator_init() in a way that now enforces to hold
the corresponding request queue's sysfs_lock when calling elevator_init()
to fix a race.
The patch did not convert the s390 dasd device driver which is the only
device driver which also calls elevator_init(). So add the missing locking.

Cc: Tomoki Sekiyama <tomoki.sekiyama@hds.com>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
drivers/s390/block/dasd.c

index 451bf99..846d5c6 100644 (file)
@@ -2978,12 +2978,12 @@ static int dasd_alloc_queue(struct dasd_block *block)
 
        elevator_exit(block->request_queue->elevator);
        block->request_queue->elevator = NULL;
+       mutex_lock(&block->request_queue->sysfs_lock);
        rc = elevator_init(block->request_queue, "deadline");
-       if (rc) {
+       if (rc)
                blk_cleanup_queue(block->request_queue);
-               return rc;
-       }
-       return 0;
+       mutex_unlock(&block->request_queue->sysfs_lock);
+       return rc;
 }
 
 /*