Hibernation: Introduce system_entering_hibernation

Introduce boolean function system_entering_hibernation() returning
'true' during the last phase of hibernation, in which devices are
being put into low power states and the sleep state (for example,
ACPI S4) is finally entered.

Some device drivers need such a function to check if the system is
in the final phase of hibernation.  In particular, some SATA drivers
are going to use it for blacklisting systems in which the disks
should not be spun down during the last phase of hibernation (the
BIOS will do that anyway).

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

1 files changed, 10 insertions, 0 deletions

diff --git a/kernel/power/disk.c b/kernel/power/disk.c
index 45e8541ab7e3..432ee575c9ee 100644
--- a/kernel/power/disk.c
+++ b/kernel/power/disk.c
@@ -71,6 +71,14 @@ void hibernation_set_ops(struct platform_hibernation_ops *ops)
         mutex_unlock(&pm_mutex);
 }
 
+static bool entering_platform_hibernation;
+
+bool system_entering_hibernation(void)
+{
+        return entering_platform_hibernation;
+}
+EXPORT_SYMBOL(system_entering_hibernation);
+
 #ifdef CONFIG_PM_DEBUG
 static void hibernation_debug_sleep(void)
 {
@@ -411,6 +419,7 @@ int hibernation_platform_enter(void)
         if (error)
                 goto Close;
 
+        entering_platform_hibernation = true;
         suspend_console();
         error = device_suspend(PMSG_HIBERNATE);
         if (error) {
@@ -445,6 +454,7 @@ int hibernation_platform_enter(void)
  Finish:
         hibernation_ops->finish();
  Resume_devices:
+        entering_platform_hibernation = false;
         device_resume(PMSG_RESTORE);
         resume_console();
  Close: