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. To fix, cleanup in reverse order of initialization. Signed-off-by: Michael S. Tsirkin <mst at 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); -- MST
On Fri, Oct 24, 2014 at 12:12 AM, Michael S. Tsirkin <mst at redhat.com> 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 <ming.lei at canonical.com>> Signed-off-by: Michael S. Tsirkin <mst at 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
Ming Lei <tom.leiming at gmail.com> writes:> On Fri, Oct 24, 2014 at 12:12 AM, Michael S. Tsirkin <mst at redhat.com> 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.Applied. Thanks, Rusty.
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