Re: [PATCH v3 2/6] nbd: disallow NBD_SET_SOCK on an active device

[yangerkun <yangerkun@huawei.com>]

在 2026/7/22 11:03, yu kuai 写道:
> Hi,
>
> 在 2026/7/13 14:56, Yang Erkun 写道:
> > We cannot add a socket to an already running nbd device, the reconfigure
> > for netlink can only active dead socket. But for ioctl path, we can call
> > NBD_SET_SOCK after NBD_DO_IT, reject this using nbd->pid which has been
> > setted when NBD_DO_IT. Besides, it is the root cause for commit
> > b98e762e3d71 ("nbd: freeze the queue while we're adding connections").
> >
> > Signed-off-by: Yang Erkun <yangerkun@huawei.com>
> > ---
> >    drivers/block/nbd.c | 7 +++++++
> >    1 file changed, 7 insertions(+)
> >
> > diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
> > index b1a5acd57426..a15553ab4b97 100644
> > --- a/drivers/block/nbd.c
> > +++ b/drivers/block/nbd.c
> > @@ -1302,6 +1302,13 @@ static int nbd_add_socket(struct nbd_device *nbd, unsigned long arg,
> >    		goto put_socket;
> >    	}
> >    
> > +	if (nbd->pid) {
> > +		dev_err(disk_to_dev(nbd->disk),
> > +			"Cannot add socket to a running device\n");
> > +		err = -EBUSY;
> > +		goto put_socket;
> > +	}
>
> I think the checking if fine, but I'd like to add the checking before nbd_get_socket() and
> return -EBUSY directly.

OK.
> > +
> >    	nsock = kzalloc_obj(*nsock);
> >    	if (!nsock) {
> >    		err = -ENOMEM;