On (Wed) 07 Dec 2011 [12:37:02], Michael S. Tsirkin wrote:
> On Wed, Dec 07, 2011 at 01:18:44AM +0530, Amit Shah wrote:
> > Delete the vq and flush any pending requests from the block queue on the
> > freeze callback to prepare for hibernation.
> >
> > Re-create the vq in the restore callback to resume normal function.
> >
> > Signed-off-by: Amit Shah <[email protected]>
> > ---
> > drivers/block/virtio_blk.c | 38 ++++++++++++++++++++++++++++++++++++++
> > 1 files changed, 38 insertions(+), 0 deletions(-)
> >
> > diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
> > index 467f218..a9147a6 100644
> > --- a/drivers/block/virtio_blk.c
> > +++ b/drivers/block/virtio_blk.c
> > @@ -568,6 +568,40 @@ static void __devexit virtblk_remove(struct
> > virtio_device *vdev)
> > ida_simple_remove(&vd_index_ida, index);
> > }
> >
> > +#ifdef CONFIG_PM
> > +static int virtblk_freeze(struct virtio_device *vdev)
> > +{
> > + struct virtio_blk *vblk = vdev->priv;
> > +
> > + /* Ensure we don't receive any more interrupts */
> > + vdev->config->reset(vdev);
> > +
> > + flush_work(&vblk->config_work);
>
> It bothers me that config work can be running
> after reset here. If it does, it will not get sane
> values from reading config.
Why so?
The reset only ensures the host doesn't write anything more, isn't it?
Why would the values be affected?
> Also, can there be stuff in the reqs list?
> If yes is this a problem?
Should be all cleared by the two commands below. At least that's my
expectation. If not, let me know!
> > + spin_lock_irq(vblk->disk->queue->queue_lock);
> > + blk_stop_queue(vblk->disk->queue);
> > + spin_unlock_irq(vblk->disk->queue->queue_lock);
> > + blk_sync_queue(vblk->disk->queue);
> > +
> > + vdev->config->del_vqs(vdev);
> > + return 0;
> > +}
> > +
>
> Thinking about it, looks like there's a bug in
> virtblk_remove: if we get a config change after
> flush_work we schedule another work.
> That's a problem for sure as structure is removed.
Yep, it is a potential issue.
Amit
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