linux-kernel - Re: [PATCH v3 14/18] xen/pvcalls: disconnect and module

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Date:   Tue, 13 Jun 2017 17:54:38 -0700 (PDT)
From:   Stefano Stabellini <sstabellini@...nel.org>
To:     Juergen Gross <jgross@...e.com>
cc:     Stefano Stabellini <sstabellini@...nel.org>,
        xen-devel@...ts.xen.org, linux-kernel@...r.kernel.org,
        boris.ostrovsky@...cle.com,
        Stefano Stabellini <stefano@...reto.com>
Subject: Re: [PATCH v3 14/18] xen/pvcalls: disconnect and module_exit

On Tue, 13 Jun 2017, Juergen Gross wrote:
> On 02/06/17 21:31, Stefano Stabellini wrote:
> > Implement backend_disconnect. Call pvcalls_back_release_active on active
> > sockets and pvcalls_back_release_passive on passive sockets.
> > 
> > Implement module_exit by calling backend_disconnect on frontend
> > connections.
> > 
> > Signed-off-by: Stefano Stabellini <stefano@...reto.com>
> > CC: boris.ostrovsky@...cle.com
> > CC: jgross@...e.com
> > ---
> >  drivers/xen/pvcalls-back.c | 49 ++++++++++++++++++++++++++++++++++++++++++++++
> >  1 file changed, 49 insertions(+)
> > 
> > diff --git a/drivers/xen/pvcalls-back.c b/drivers/xen/pvcalls-back.c
> > index b541887..6afe7a0 100644
> > --- a/drivers/xen/pvcalls-back.c
> > +++ b/drivers/xen/pvcalls-back.c
> > @@ -800,6 +800,38 @@ static int backend_connect(struct xenbus_device *dev)
> >  
> >  static int backend_disconnect(struct xenbus_device *dev)
> >  {
> > +	struct pvcalls_fedata *priv;
> > +	struct sock_mapping *map, *n;
> > +	struct sockpass_mapping *mappass;
> > +	struct radix_tree_iter iter;
> > +	void **slot;
> > +
> > +
> > +	priv = dev_get_drvdata(&dev->dev);
> > +
> > +	list_for_each_entry_safe(map, n, &priv->socket_mappings, list) {
> > +		pvcalls_back_release_active(dev, priv, map);
> > +	}
> 
> You can drop the {}

OK


> > +
> > +	radix_tree_for_each_slot(slot, &priv->socketpass_mappings, &iter, 0) {
> > +		mappass = radix_tree_deref_slot(slot);
> > +		if (!mappass || radix_tree_exception(mappass)) {
> 
> This looks fishy.
> 
> You might call radix_tree_deref_retry(NULL). Right now this is okay,
> but you depend on the radix tree internals here.

I'll avoid id


> > +			if (radix_tree_deref_retry(mappass)) {
> > +				slot = radix_tree_iter_retry(&iter);
> > +				continue;
> 
> The continue; statement is pointless here.

I'll remove it


> > +			}
> > +		} else
> > +			pvcalls_back_release_passive(dev, priv, mappass);
> > +	}
> > +
> > +	xenbus_unmap_ring_vfree(dev, (void *)priv->sring);
> 
> Drop the cast.

OK


> > +	unbind_from_irqhandler(priv->irq, dev);
> > +
> > +	list_del(&priv->list);
> > +	destroy_workqueue(priv->wq);
> > +	kfree(priv);
> > +	dev_set_drvdata(&dev->dev, NULL);
> > +
> >  	return 0;
> >  }
> >  
> > @@ -993,3 +1025,20 @@ static int __init pvcalls_back_init(void)
> >  	return 0;
> >  }
> >  module_init(pvcalls_back_init);
> > +
> > +static void __exit pvcalls_back_fin(void)
> > +{
> > +	struct pvcalls_fedata *priv, *npriv;
> > +
> > +	down(&pvcalls_back_global.frontends_lock);
> > +	list_for_each_entry_safe(priv, npriv, &pvcalls_back_global.frontends,
> > +				 list) {
> > +		backend_disconnect(priv->dev);
> > +	}
> > +	up(&pvcalls_back_global.frontends_lock);
> > +
> > +	xenbus_unregister_driver(&pvcalls_back_driver);
> > +	memset(&pvcalls_back_global, 0, sizeof(pvcalls_back_global));
> 
> Why?

legacy code, I'll remove it


> Juergen
> 
> > +}
> > +
> > +module_exit(pvcalls_back_fin);
> > 
>