elv_unregister: fix possible crash on module unload

An exiting task or process which didn't do I/O yet have no io context, elv_unregister() should check it is not NULL. Signed-off-by: Oleg Nesterov <[email protected]> Acked-by: Jens Axboe <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>
mna · Aug 22, 2006 · 2d8f613 · 2d8f613
1 parent 00a2b0f
commit 2d8f613
Showing 1 changed file with 2 additions and 1 deletion.
diff --git a/block/elevator.c b/block/elevator.c
@@ -765,7 +765,8 @@ void elv_unregister(struct elevator_type *e)
 		read_lock(&tasklist_lock);
 		do_each_thread(g, p) {
 			task_lock(p);
-			e->ops.trim(p->io_context);
+			if (p->io_context)
+				e->ops.trim(p->io_context);
 			task_unlock(p);
 		} while_each_thread(g, p);
 		read_unlock(&tasklist_lock);