On 09/17/2019 01:40 PM, Josef Bacik wrote: >>> + nbd->destroy_complete = &destroy_complete; >> >> Also, without the mutex part of the v3 patch, we could race and >> nbd_dev_remove could have passed the destroy_complete check already, so >> below we will wait forever. >> > > Oh hmm you're right, I think I am actually wrong about that part too now :) I had forgot about the idr removal under the mutex when making my original comment. If nbd_put grabs the mutex first then it will do idr_remove under the mutex. If nbd_genl_connect then runs, idr_find/idr_for_each will fail and we will allocate a new nbd device and NBD_DISCONNECT_REQUESTED will not be set. If nbd_genl_connect grabs the mutex first, then idr_find/idr_for_each will succeed and we will set the completion. nbd_put will then grab the mutex and call nbd_remove_dev and see the completion.
