linux-kernel - Re: [PATCH v4 02/13] xen/pvcalls: implement frontend disconnect

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Date:   Wed, 20 Sep 2017 16:59:19 -0400
From:   Boris Ostrovsky <boris.ostrovsky@...cle.com>
To:     Stefano Stabellini <sstabellini@...nel.org>,
        xen-devel@...ts.xen.org
Cc:     linux-kernel@...r.kernel.org, jgross@...e.com,
        Stefano Stabellini <stefano@...reto.com>
Subject: Re: [PATCH v4 02/13] xen/pvcalls: implement frontend disconnect


>  
>  static int pvcalls_front_remove(struct xenbus_device *dev)
>  {
> +	struct pvcalls_bedata *bedata;
> +	struct sock_mapping *map = NULL, *n;
> +
> +	bedata = dev_get_drvdata(&pvcalls_front_dev->dev);
> +	dev_set_drvdata(&dev->dev, NULL);
> +	pvcalls_front_dev = NULL;

One more comment on this patch: should this be the last thing to do?
pvcalls_front_dev is what prevents pvcalls_front_probe() from proceeding
and even though I am not sure a probe can be initiated while we are here
perhaps moving this to the end would make things slightly safer.

-boris


> +	if (bedata->irq >= 0)
> +		unbind_from_irqhandler(bedata->irq, dev);
> +
> +	smp_mb();
> +	while (atomic_read(&pvcalls_refcount) > 0)
> +		cpu_relax();
> +	list_for_each_entry_safe(map, n, &bedata->socket_mappings, list) {
> +		pvcalls_front_free_map(bedata, map);
> +		kfree(map);
> +	}
> +	list_for_each_entry_safe(map, n, &bedata->socketpass_mappings, list) {
> +		spin_lock(&bedata->socket_lock);
> +		list_del_init(&map->list);
> +		spin_unlock(&bedata->socket_lock);
> +		kfree(map);
> +	}
> +	if (bedata->ref >= 0)
> +		gnttab_end_foreign_access(bedata->ref, 0, 0);
> +	kfree(bedata->ring.sring);
> +	kfree(bedata);
> +	xenbus_switch_state(dev, XenbusStateClosed);
>  	return 0;
>  }
>