Re: [PATCH 11/20] nbd: request_fn fixup

[Jens Axboe <axboe@kernel.dk>]

On Tue, Sep 12 2006, Jeff Garzik wrote:
> Jens Axboe wrote:
> >Generally the block device rule is that once you are invoked due to an
> >unplug (or whatever) event, it is the responsibility of the block device
> >to run the queue until it's done. So if you bail out of queue handling
> >for whatever reason (might be resource starvation in hard- or software),
> >you must make sure to reenter queue handling since the device will not
> >get replugged while it has requests pending. Unless you run into some
> >software resource shortage, running of the queue is done
> >deterministically when you know resources are available (ie an io
> >completes). The device plugging itself is only ever done when you
> >encounter a shortage outside of your control (memory shortage, for
> >instance) _and_ you don't already have pending work where you can invoke
> >queueing from again.
> 
> Or he could employ the blk_{start,stop}_queue() functions, if that model 
> is easier for the driver (and brain).

Definitely, yes.

-- 
Jens Axboe