kernel/reboot: Add kernel_can_power_off()

Add kernel_can_power_off() helper that replaces open-coded checks of
the global pm_power_off variable. This is a necessary step towards
supporting chained power-off handlers.

Signed-off-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

1 files changed, 13 insertions, 1 deletions

diff --git a/kernel/reboot.c b/kernel/reboot.c
index 7723aff4d09b..fb3f49350927 100644
--- a/kernel/reboot.c
+++ b/kernel/reboot.c
@@ -524,6 +524,18 @@ void do_kernel_power_off(void)
 }
 
 /**
+ *	kernel_can_power_off - check whether system can be powered off
+ *
+ *	Returns true if power-off handler is registered and system can be
+ *	powered off, false otherwise.
+ */
+bool kernel_can_power_off(void)
+{
+	return !atomic_notifier_call_chain_is_empty(&power_off_handler_list);
+}
+EXPORT_SYMBOL_GPL(kernel_can_power_off);
+
+/**
  *	kernel_power_off - power_off the system
  *
  *	Shutdown everything and perform a clean system power_off.
@@ -581,7 +593,7 @@ SYSCALL_DEFINE4(reboot, int, magic1, int, magic2, unsigned int, cmd,
 	/* Instead of trying to make the power_off code look like
 	 * halt when pm_power_off is not set do it the easy way.
 	 */
-	if ((cmd == LINUX_REBOOT_CMD_POWER_OFF) && !pm_power_off)
+	if ((cmd == LINUX_REBOOT_CMD_POWER_OFF) && !kernel_can_power_off())
 		cmd = LINUX_REBOOT_CMD_HALT;
 
 	mutex_lock(&system_transition_mutex);