On 9/19/19 12:14 AM, xiubli@xxxxxxxxxx wrote: > From: Xiubo Li <xiubli@xxxxxxxxxx> > > 1. nbd_put takes the mutex and drops nbd->ref to 0. It then does > idr_remove and drops the mutex. > > 2. nbd_genl_connect takes the mutex. idr_find/idr_for_each fails > to find an existing device, so it does nbd_dev_add. > > 3. just before the nbd_put could call nbd_dev_remove or not finished > totally, but if nbd_dev_add try to add_disk, we can hit: > > debugfs: Directory 'nbd1' with parent 'block' already present! > > This patch will make sure all the disk add/remove stuff are done > by holding the nbd_index_mutex lock. Applied, thanks. -- Jens Axboe
