linux-kernel - Re: [PATCH v3 13/18] xen/pvcalls: implement release command

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Message-ID: <alpine.DEB.2.10.1706131745420.12156@sstabellini-ThinkPad-X260>
Date:   Tue, 13 Jun 2017 17:47:38 -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 13/18] xen/pvcalls: implement release command

On Tue, 13 Jun 2017, Juergen Gross wrote:
> On 02/06/17 21:31, Stefano Stabellini wrote:
> > Release both active and passive sockets. For active sockets, make sure
> > to avoid possible conflicts with the ioworker reading/writing to those
> > sockets concurrently. Set map->release to let the ioworker know
> > atomically that the socket will be released soon, then wait until the
> > ioworker finishes (flush_work).
> > 
> > Unmap indexes pages and data rings.
> > 
> > Signed-off-by: Stefano Stabellini <stefano@...reto.com>
> > CC: boris.ostrovsky@...cle.com
> > CC: jgross@...e.com
> > ---
> >  drivers/xen/pvcalls-back.c | 72 +++++++++++++++++++++++++++++++++++++++++++++-
> >  1 file changed, 71 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/xen/pvcalls-back.c b/drivers/xen/pvcalls-back.c
> > index 82f350d..b541887 100644
> > --- a/drivers/xen/pvcalls-back.c
> > +++ b/drivers/xen/pvcalls-back.c
> > @@ -265,13 +265,83 @@ static int pvcalls_back_release_active(struct xenbus_device *dev,
> >  				       struct pvcalls_fedata *priv,
> >  				       struct sock_mapping *map)
> >  {
> > +	disable_irq(map->irq);
> > +	if (map->sock->sk != NULL) {
> > +		write_lock_bh(&map->sock->sk->sk_callback_lock);
> > +		map->sock->sk->sk_user_data = NULL;
> > +		map->sock->sk->sk_data_ready = map->saved_data_ready;
> > +		write_unlock_bh(&map->sock->sk->sk_callback_lock);
> > +	}
> > +
> > +	atomic_set(&map->release, 1);
> > +	flush_work(&map->ioworker.register_work);
> > +
> > +	down(&priv->socket_lock);
> > +	list_del(&map->list);
> > +	up(&priv->socket_lock);
> > +
> > +	xenbus_unmap_ring_vfree(dev, (void *)map->bytes);
> > +	xenbus_unmap_ring_vfree(dev, (void *)map->ring);
> 
> I don't think you need the casts to (void*) here.

OK

> > +	unbind_from_irqhandler(map->irq, map);
> > +
> > +	sock_release(map->sock);
> > +	kfree(map);
> > +
> > +	return 0;
> > +}
> > +
> > +static int pvcalls_back_release_passive(struct xenbus_device *dev,
> > +					struct pvcalls_fedata *priv,
> > +					struct sockpass_mapping *mappass)
> > +{
> > +	if (mappass->sock->sk != NULL) {
> > +		write_lock_bh(&mappass->sock->sk->sk_callback_lock);
> > +		mappass->sock->sk->sk_user_data = NULL;
> > +		mappass->sock->sk->sk_data_ready = mappass->saved_data_ready;
> > +		write_unlock_bh(&mappass->sock->sk->sk_callback_lock);
> > +	}
> > +	down(&priv->socket_lock);
> > +	radix_tree_delete(&priv->socketpass_mappings, mappass->id);
> > +	sock_release(mappass->sock);
> > +	flush_workqueue(mappass->wq);
> > +	destroy_workqueue(mappass->wq);
> > +	kfree(mappass);
> > +	up(&priv->socket_lock);
> > +
> >  	return 0;
> >  }
> >  
> >  static int pvcalls_back_release(struct xenbus_device *dev,
> >  				struct xen_pvcalls_request *req)
> >  {
> > -	return 0;
> > +	struct pvcalls_fedata *priv;
> > +	struct sock_mapping *map, *n;
> > +	struct sockpass_mapping *mappass;
> > +	int ret = 0;
> > +	struct xen_pvcalls_response *rsp;
> > +
> > +	priv = dev_get_drvdata(&dev->dev);
> > +
> > +	list_for_each_entry_safe(map, n, &priv->socket_mappings, list) {
> > +		if (map->id == req->u.release.id) {
> > +			ret = pvcalls_back_release_active(dev, priv, map);
> > +			goto out;
> > +		}
> > +	}
> > +	mappass = radix_tree_lookup(&priv->socketpass_mappings,
> > +				    req->u.release.id);
> > +	if (mappass != NULL) {
> > +		ret = pvcalls_back_release_passive(dev, priv, mappass);
> > +		goto out;
> > +	}
> > +
> > +out:
> > +	rsp = RING_GET_RESPONSE(&priv->ring, priv->ring.rsp_prod_pvt++);
> > +	rsp->req_id = req->req_id;
> > +	rsp->u.release.id = req->u.release.id;
> > +	rsp->cmd = req->cmd;
> > +	rsp->ret = ret;
> > +	return ret;
> 
> return 0;

OK