[PATCH] block cleanups: Fix iosched module refcount leak

Nate Diller · Linus Torvalds · commit 2ca7d93bb278 · 2005-10-30T17:37:20.000-08:00
If the requested I/O scheduler is already in place, elevator_switch simply
leaves the queue alone, and returns.  However, it forgets to call
elevator_put, so

'echo [current_sched] &gt; /sys/block/[dev]/queue/scheduler'

will leak a reference, causing the current_sched module to be permanently
pinned in memory.

Signed-off-by: Nate Diller &lt;nate@namesys.com&gt;
Acked-by: Jens Axboe &lt;axboe@suse.de&gt;
Signed-off-by: Andrew Morton &lt;akpm@osdl.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@osdl.org&gt;
diff --git a/drivers/block/elevator.c b/drivers/block/elevator.c
@@ -753,8 +753,10 @@ ssize_t elv_iosched_store(request_queue_t *q, const char *name, size_t count)
 		return -EINVAL;
 	}
 
-	if (!strcmp(elevator_name, q->elevator->elevator_type->elevator_name))
+	if (!strcmp(elevator_name, q->elevator->elevator_type->elevator_name)) {
+		elevator_put(e);
 		return count;
+	}
 
 	elevator_switch(q, e);
 	return count;
