[PATCH] fix swsusp on machines not supporting S4

Fix swsusp on machines not supporting S4. With recent changes, it is not
possible to trigger it using /sys filesystem. Swsusp does not really need
any support from low-level code, it is possible to reboot or halt at the
end of suspend.

Signed-off-by: Pavel Machek <[e-mail]>
Cc: "Brown, Len" <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

kernel/power/main.c

···
 
 DECLARE_MUTEX(pm_sem);
 
-struct pm_ops * pm_ops = NULL;
+struct pm_ops *pm_ops;
 suspend_disk_method_t pm_disk_mode = PM_DISK_SHUTDOWN;
 
 /**
···
 #endif
 };
 
+static inline int valid_state(suspend_state_t state)
+{
+	/* Suspend-to-disk does not really need low-level support.
+	 * It can work with reboot if needed. */
+	if (state == PM_SUSPEND_DISK)
+		return 1;
+
+	if (pm_ops && pm_ops->valid && !pm_ops->valid(state))
+		return 0;
+	return 1;
+}
+
 
 /**
  *	enter_state - Do common work of entering low-power state.
···
 {
 	int error;
 
-	if (pm_ops && pm_ops->valid && !pm_ops->valid(state))
+	if (!valid_state(state))
 		return -ENODEV;
 	if (down_trylock(&pm_sem))
 		return -EBUSY;
···
 	char * s = buf;
 
 	for (i = 0; i < PM_SUSPEND_MAX; i++) {
-		if (pm_states[i] && pm_ops && (!pm_ops->valid
-			||(pm_ops->valid && pm_ops->valid(i))))
-			s += sprintf(s,"%s ",pm_states[i]);
+		if (pm_states[i] && valid_state(i))
+			s += sprintf(s,"%s ", pm_states[i]);
 	}
 	s += sprintf(s,"\n");
 	return (s - buf);