Subject: Re: [PATCH v2] xenbus: advertize control feature flags
To: Paul Durrant <paul.durrant@citrix.com>, linux-kernel@vger.kernel.org,
        xen-devel@lists.xenproject.org
References: <1476092625-14616-1-git-send-email-paul.durrant@citrix.com>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>,
        David Vrabel <david.vrabel@citrix.com>
From: Juergen Gross <jgross@suse.com>
Message-ID: <5e726d3e-a718-a68a-6d9e-4c888cc0ff06@suse.com>
Date: Mon, 10 Oct 2016 12:09:46 +0200
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On 10/10/16 11:43, Paul Durrant wrote:
> The Xen docs specify several flags which a guest can set to advertize
> which values of the xenstore control/shutdown key it will recognize.
> This patch adds code to write all the relevant feature-flag keys.
> 
> Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
> Cc: David Vrabel <david.vrabel@citrix.com>
> Cc: Juergen Gross <jgross@suse.com>
> ---
> 
> v2:
>  - Fix flag logic inversion
>  - Use kasprintf()
> ---
>  drivers/xen/manage.c | 38 ++++++++++++++++++++++++++++----------
>  1 file changed, 28 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/xen/manage.c b/drivers/xen/manage.c
> index e12bd36..0671b98 100644
> --- a/drivers/xen/manage.c
> +++ b/drivers/xen/manage.c
> @@ -170,6 +170,7 @@ out:
>  struct shutdown_handler {
>  	const char *command;
>  	void (*cb)(void);
> +	bool flag;
>  };
>  
>  static int poweroff_nb(struct notifier_block *cb, unsigned long code, void *unused)
> @@ -206,21 +207,22 @@ static void do_reboot(void)
>  	ctrl_alt_del();
>  }
>  
> +static struct shutdown_handler shutdown_handlers[] = {
> +	{ "poweroff", do_poweroff, true },
> +	{ "halt", do_poweroff, false },
> +	{ "reboot", do_reboot, true },
> +#ifdef CONFIG_HIBERNATE_CALLBACKS
> +	{ "suspend", do_suspend, true },
> +#endif
> +	{NULL, NULL, false },
> +};
> +
>  static void shutdown_handler(struct xenbus_watch *watch,
>  			     const char **vec, unsigned int len)
>  {
>  	char *str;
>  	struct xenbus_transaction xbt;
>  	int err;
> -	static struct shutdown_handler handlers[] = {
> -		{ "poweroff",	do_poweroff },
> -		{ "halt",	do_poweroff },
> -		{ "reboot",	do_reboot   },
> -#ifdef CONFIG_HIBERNATE_CALLBACKS
> -		{ "suspend",	do_suspend  },
> -#endif
> -		{NULL, NULL},
> -	};
>  	static struct shutdown_handler *handler;
>  
>  	if (shutting_down != SHUTDOWN_INVALID)
> @@ -238,7 +240,7 @@ static void shutdown_handler(struct xenbus_watch *watch,
>  		return;
>  	}
>  
> -	for (handler = &handlers[0]; handler->command; handler++) {
> +	for (handler = &shutdown_handlers[0]; handler->command; handler++) {
>  		if (strcmp(str, handler->command) == 0)
>  			break;
>  	}
> @@ -309,8 +311,24 @@ static struct notifier_block xen_reboot_nb = {
>  
>  static int setup_shutdown_watcher(void)
>  {
> +	static struct shutdown_handler *handler;
>  	int err;
>  
> +	for (handler = &shutdown_handlers[0]; handler->command; handler++) {
> +		char *node;
> +
> +		node = kasprintf(GFP_KERNEL, "feature-%s",
> +				 handler->command);

Now you've dropped using flag?


Juergen