Re: [PATCH] virtio_blk: fix race at module removal
From: Ming Lei <tom.leiming@gmail.com>
Date: 2014-10-24 02:13:05
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On Fri, Oct 24, 2014 at 12:12 AM, Michael S. Tsirkin [off-list ref] wrote:
If a device appears while module is being removed, driver will get a callback after we've given up on the major number. In theory this means this major number can get reused by something else, resulting in a conflict.
Yes, there is a tiny race window.
To fix, cleanup in reverse order of initialization.
Reviewed-by: Ming Lei <redacted>
quoted hunk ↗ jump to hunk
Signed-off-by: Michael S. Tsirkin <mst@redhat.com> --- drivers/block/virtio_blk.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c index 56aadbc..adfba9f 100644 --- a/drivers/block/virtio_blk.c +++ b/drivers/block/virtio_blk.c@@ -883,8 +883,8 @@ out_destroy_workqueue: static void __exit fini(void) { - unregister_blkdev(major, "virtblk"); unregister_virtio_driver(&virtio_blk); + unregister_blkdev(major, "virtblk"); destroy_workqueue(virtblk_wq); } module_init(init);
Thanks, -- Ming Lei