Re: [PATCH] virtio_blk: allow re-reading config space at runtime

[Michael S. Tsirkin]

On Tue, Feb 01, 2011 at 06:32:34PM +0100, Christoph Hellwig wrote:
> On Thu, Jan 27, 2011 at 05:29:26PM +0200, Michael S. Tsirkin wrote:
> > Yes but in that specific situation (double schedule before
> > it runs once) discarding one change notification
> > would not hurt at all.
> 
> Except that you can't easily do it.  We can't simply reuse a work
> structure embedded in say struct virtio_blk without first doing a
> flush_work_sync/cancel_work_sync to remove it from the internal
> workqueue.c queues.
>  And those calls can sleep and thus can't be called
> from interrupt context either.

Should not be hard to solve.
If it's running, it is ok to requeue.  I don't remember offhand if it's
ok to requeue if it's queued but not running, if not we could have a
flag that signals that's the case.

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