[PATCH V2 09/13] scsi: force unfreezing queue into atomic mode

[Christoph Hellwig]

On Tue, Jan 25, 2022 at 07:21:55AM +0800, Ming Lei wrote:
> > > @@ -3670,7 +3670,7 @@ static void scsi_disk_release(struct device *dev)
> > >  	 * in case multiple processes open a /dev/sd... node concurrently.
> > >  	 */
> > >  	blk_mq_freeze_queue(q);
> > > -	blk_mq_unfreeze_queue(q);
> > > +	__blk_mq_unfreeze_queue(q, true);
> > 
> > I think the right thing here is to drop the freeze/unfreeze pair.
> > Now that del_gendisk properly freezes the queue, we don't need this
> > protection as the issue that Bart fixed with it can't happen any more.
> 
> As you see, the last patch removes freeze/unfreeze pair in del_gendisk(),
> which looks not very useful: it can't drain IO on bio based driver, and
> del_gendisk() is supposed to provide consistent behavior for both request
> and bio based driver.

So what is the advantage of trying to remove the freeze from where
it belongs (common unregister code) while keeping it where it is a bandaid
(driver specific unregister code)?