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

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Date:   Tue, 13 Jun 2017 09:49:16 +0200
From:   Juergen Gross <jgross@...e.com>
To:     Stefano Stabellini <sstabellini@...nel.org>,
        xen-devel@...ts.xen.org
Cc:     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 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 {}

> +
> +	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.

> +			if (radix_tree_deref_retry(mappass)) {
> +				slot = radix_tree_iter_retry(&iter);
> +				continue;

The continue; statement is pointless here.

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

Drop the cast.

> +	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?


Juergen

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