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Subject: Re: [PATCH v1 01/13] xen/pvcalls: introduce the pvcalls xenbus
 frontend
To: Stefano Stabellini <sstabellini@kernel.org>, xen-devel@lists.xen.org
Cc: linux-kernel@vger.kernel.org, boris.ostrovsky@oracle.com,
        Stefano Stabellini <stefano@aporeto.com>
References: <alpine.DEB.2.10.1707201553090.22381@sstabellini-ThinkPad-X260>
 <1500682323-25940-1-git-send-email-sstabellini@kernel.org>
From: Juergen Gross <jgross@suse.com>
Message-ID: <7905bebe-39a0-380f-139d-66ee48c7e853@suse.com>
Date: Mon, 24 Jul 2017 21:06:20 +0200
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On 22/07/17 02:11, Stefano Stabellini wrote:
> Introduce a xenbus frontend for the pvcalls protocol, as defined by
> https://xenbits.xen.org/docs/unstable/misc/pvcalls.html.
> 
> This patch only adds the stubs, the code will be added by the following
> patches.
> 
> Signed-off-by: Stefano Stabellini <stefano@aporeto.com>
> CC: boris.ostrovsky@oracle.com
> CC: jgross@suse.com
> ---
>  drivers/xen/pvcalls-front.c | 68 +++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 68 insertions(+)
>  create mode 100644 drivers/xen/pvcalls-front.c
> 
> diff --git a/drivers/xen/pvcalls-front.c b/drivers/xen/pvcalls-front.c
> new file mode 100644
> index 0000000..173e204
> --- /dev/null
> +++ b/drivers/xen/pvcalls-front.c
> @@ -0,0 +1,68 @@
> +/*
> + * (c) 2017 Stefano Stabellini <stefano@aporeto.com>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + */
> +
> +#include <linux/module.h>
> +
> +#include <xen/events.h>
> +#include <xen/grant_table.h>
> +#include <xen/xen.h>
> +#include <xen/xenbus.h>
> +#include <xen/interface/io/pvcalls.h>
> +
> +static const struct xenbus_device_id pvcalls_front_ids[] = {
> +	{ "pvcalls" },
> +	{ "" }
> +};
> +
> +static int pvcalls_front_remove(struct xenbus_device *dev)
> +{
> +	return 0;
> +}
> +
> +static int pvcalls_front_probe(struct xenbus_device *dev,
> +			  const struct xenbus_device_id *id)
> +{
> +	return 0;
> +}
> +
> +static int pvcalls_front_resume(struct xenbus_device *dev)
> +{
> +	dev_warn(&dev->dev, "suspsend/resume unsupported\n");
> +	return 0;
> +}

Why are you adding a resume function doing nothing but issuing a
message? Just omit it.


Juergen

> +
> +static void pvcalls_front_changed(struct xenbus_device *dev,
> +			    enum xenbus_state backend_state)
> +{
> +}
> +
> +static struct xenbus_driver pvcalls_front_driver = {
> +	.ids = pvcalls_front_ids,
> +	.probe = pvcalls_front_probe,
> +	.remove = pvcalls_front_remove,
> +	.resume = pvcalls_front_resume,
> +	.otherend_changed = pvcalls_front_changed,
> +};
> +
> +static int __init pvcalls_frontend_init(void)
> +{
> +	if (!xen_domain())
> +		return -ENODEV;
> +
> +	pr_info("Initialising Xen pvcalls frontend driver\n");
> +
> +	return xenbus_register_frontend(&pvcalls_front_driver);
> +}
> +
> +module_init(pvcalls_frontend_init);
>