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>

diff --git a/include/linux/reboot.h b/include/linux/reboot.h
index 99a9753..5837c6c 100644 (file)
--- a/include/linux/reboot.h
+++ b/include/linux/reboot.h
@@ -149,6 +149,7 @@ extern void kernel_restart_prepare(char *cmd);
 extern void kernel_restart(char *cmd);
 extern void kernel_halt(void);
 extern void kernel_power_off(void);
+extern bool kernel_can_power_off(void);
 
 extern int C_A_D; /* for sysctl */
 void ctrl_alt_del(void);

diff --git a/kernel/reboot.c b/kernel/reboot.c
index 7723aff..fb3f493 100644 (file)
--- 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);