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Commit 3e2b8fbe authored by Jeremy Fitzhardinge's avatar Jeremy Fitzhardinge Committed by Jeremy Fitzhardinge
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xen: handle external requests for shutdown, reboot and sysrq 



The guest domain can be asked to shutdown or reboot itself, or have a
sysrq key injected, via xenbus.  This patch adds a watcher for those
events, and does the appropriate action.

Signed-off-by: default avatarJeremy Fitzhardinge <jeremy@xensource.com>
Cc: Chris Wright <chrisw@sous-sol.org>
parent fefa629a

arch/i386/xen/Makefile

+1 −1
Original line number Diff line number Diff line 
obj-y		:= enlighten.o setup.o features.o multicalls.o mmu.o \

			events.o time.o

			events.o time.o manage.o



obj-$(CONFIG_SMP)	+= smp.o

arch/i386/xen/manage.c

0 → 100644
+143 −0
Original line number Diff line number Diff line 
/*

 * Handle extern requests for shutdown, reboot and sysrq

 */

#include <linux/kernel.h>

#include <linux/err.h>

#include <linux/reboot.h>

#include <linux/sysrq.h>



#include <xen/xenbus.h>



#define SHUTDOWN_INVALID  -1

#define SHUTDOWN_POWEROFF  0

#define SHUTDOWN_SUSPEND   2

/* Code 3 is SHUTDOWN_CRASH, which we don't use because the domain can only

 * report a crash, not be instructed to crash!

 * HALT is the same as POWEROFF, as far as we're concerned.  The tools use

 * the distinction when we return the reason code to them.

 */

#define SHUTDOWN_HALT      4



/* Ignore multiple shutdown requests. */

static int shutting_down = SHUTDOWN_INVALID;



static void shutdown_handler(struct xenbus_watch *watch,

			     const char **vec, unsigned int len)

{

	char *str;

	struct xenbus_transaction xbt;

	int err;



	if (shutting_down != SHUTDOWN_INVALID)

		return;



 again:

	err = xenbus_transaction_start(&xbt);

	if (err)

		return;



	str = (char *)xenbus_read(xbt, "control", "shutdown", NULL);

	/* Ignore read errors and empty reads. */

	if (XENBUS_IS_ERR_READ(str)) {

		xenbus_transaction_end(xbt, 1);

		return;

	}



	xenbus_write(xbt, "control", "shutdown", "");



	err = xenbus_transaction_end(xbt, 0);

	if (err == -EAGAIN) {

		kfree(str);

		goto again;

	}



	if (strcmp(str, "poweroff") == 0 ||

	    strcmp(str, "halt") == 0)

		orderly_poweroff(false);

	else if (strcmp(str, "reboot") == 0)

		ctrl_alt_del();

	else {

		printk(KERN_INFO "Ignoring shutdown request: %s\n", str);

		shutting_down = SHUTDOWN_INVALID;

	}



	kfree(str);

}



static void sysrq_handler(struct xenbus_watch *watch, const char **vec,

			  unsigned int len)

{

	char sysrq_key = '\0';

	struct xenbus_transaction xbt;

	int err;



 again:

	err = xenbus_transaction_start(&xbt);

	if (err)

		return;

	if (!xenbus_scanf(xbt, "control", "sysrq", "%c", &sysrq_key)) {

		printk(KERN_ERR "Unable to read sysrq code in "

		       "control/sysrq\n");

		xenbus_transaction_end(xbt, 1);

		return;

	}



	if (sysrq_key != '\0')

		xenbus_printf(xbt, "control", "sysrq", "%c", '\0');



	err = xenbus_transaction_end(xbt, 0);

	if (err == -EAGAIN)

		goto again;



	if (sysrq_key != '\0')

		handle_sysrq(sysrq_key, NULL);

}



static struct xenbus_watch shutdown_watch = {

	.node = "control/shutdown",

	.callback = shutdown_handler

};



static struct xenbus_watch sysrq_watch = {

	.node = "control/sysrq",

	.callback = sysrq_handler

};



static int setup_shutdown_watcher(void)

{

	int err;



	err = register_xenbus_watch(&shutdown_watch);

	if (err) {

		printk(KERN_ERR "Failed to set shutdown watcher\n");

		return err;

	}



	err = register_xenbus_watch(&sysrq_watch);

	if (err) {

		printk(KERN_ERR "Failed to set sysrq watcher\n");

		return err;

	}



	return 0;

}



static int shutdown_event(struct notifier_block *notifier,

			  unsigned long event,

			  void *data)

{

	setup_shutdown_watcher();

	return NOTIFY_DONE;

}



static int __init setup_shutdown_event(void)

{

	static struct notifier_block xenstore_notifier = {

		.notifier_call = shutdown_event

	};

	register_xenstore_notifier(&xenstore_notifier);



	return 0;

}



subsys_initcall(setup_shutdown_event);