PM / sleep: Fix test_suspend= command line option

After commit d431cbc5 (PM / sleep: Simplify sleep states sysfs
interface code) the pm_states[] array is not populated initially,
which causes setup_test_suspend() to always fail and the suspend
testing during boot doesn't work any more.

Fix the problem by using pm_labels[] instead of pm_states[] in
setup_test_suspend() and storing a pointer to the label of the
sleep state to test rather than the number representing it,
because the connection between the state numbers and labels is
only established by suspend_set_ops().

Fixes: d431cbc5 (PM / sleep: Simplify sleep states sysfs interface code)
Reported-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

kernel/power/power.h

@@ -179,6 +179,7 @@ extern void swsusp_show_speed(struct timeval *, struct timeval *,
 
 #ifdef CONFIG_SUSPEND
 /* kernel/power/suspend.c */
+extern const char *pm_labels[];
 extern const char *pm_states[];
 
 extern int suspend_devices_and_enter(suspend_state_t state);

kernel/power/suspend.c

@@ -31,7 +31,7 @@
 
 #include "power.h"
 
-static const char *pm_labels[] = { "mem", "standby", "freeze", };
+const char *pm_labels[] = { "mem", "standby", "freeze", NULL };
 const char *pm_states[PM_SUSPEND_MAX];
 
 static const struct platform_suspend_ops *suspend_ops;

kernel/power/suspend_test.c

@@ -129,20 +129,20 @@ static int __init has_wakealarm(struct device *dev, const void *data)
  * at startup time.  They're normally disabled, for faster boot and because
  * we can't know which states really work on this particular system.
  */
-static suspend_state_t test_state __initdata = PM_SUSPEND_ON;
+static const char *test_state_label __initdata;
 
 static char warn_bad_state[] __initdata =
 	KERN_WARNING "PM: can't test '%s' suspend state\n";
 
 static int __init setup_test_suspend(char *value)
 {
-	suspend_state_t i;
+	int i;
 
 	/* "=mem" ==> "mem" */
 	value++;
-	for (i = PM_SUSPEND_MIN; i < PM_SUSPEND_MAX; i++)
-		if (!strcmp(pm_states[i], value)) {
-			test_state = i;
+	for (i = 0; pm_labels[i]; i++)
+		if (!strcmp(pm_labels[i], value)) {
+			test_state_label = pm_labels[i];
 			return 0;
 		}
 
@@ -158,13 +158,21 @@ static int __init test_suspend(void)
 
 	struct rtc_device	*rtc = NULL;
 	struct device		*dev;
+	suspend_state_t test_state;
 
 	/* PM is initialized by now; is that state testable? */
-	if (test_state == PM_SUSPEND_ON)
-		goto done;
-	if (!pm_states[test_state]) {
-		printk(warn_bad_state, pm_states[test_state]);
-		goto done;
+	if (!test_state_label)
+		return 0;
+
+	for (test_state = PM_SUSPEND_MIN; test_state < PM_SUSPEND_MAX; test_state++) {
+		const char *state_label = pm_states[test_state];
+
+		if (state_label && !strcmp(test_state_label, state_label))
+			break;
+	}
+	if (test_state == PM_SUSPEND_MAX) {
+		printk(warn_bad_state, test_state_label);
+		return 0;
 	}
 
 	/* RTCs have initialized by now too ... can we use one? */
@@ -173,13 +181,12 @@ static int __init test_suspend(void)
 		rtc = rtc_class_open(dev_name(dev));
 	if (!rtc) {
 		printk(warn_no_rtc);
-		goto done;
+		return 0;
 	}
 
 	/* go for it */
 	test_wakealarm(rtc, test_state);
 	rtc_class_close(rtc);
-done:
 	return 0;
 }
 late_initcall(test_suspend);