summaryrefslogtreecommitdiff
path: root/drivers/xen/manage.c
blob: aa7af9e6abc05ac622da6930ab87e8f731f802bd (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
/*
 * 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);