Suspend: Add config option to disable the freezer if architecture wants that

This patch makes the freezer optional for suspend to allow the
system to work (or not work) like the original PMU suspend.
Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Len Brown <len.brown@intel.com>

arch/powerpc/Kconfig

@@ -405,6 +405,10 @@ config CMDLINE
 	  most cases you will need to specify the root device here.
 
 if !44x || BROKEN
+config ARCH_WANTS_FREEZER_CONTROL
+	def_bool y
+	depends on ADB_PMU
+
 source kernel/power/Kconfig
 endif
 

kernel/power/Kconfig

@@ -104,6 +104,17 @@ config SUSPEND
 	  powered and thus its contents are preserved, such as the
 	  suspend-to-RAM state (e.g. the ACPI S3 state).
 
+config SUSPEND_FREEZER
+	bool "Enable freezer for suspend to RAM/standby" \
+		if ARCH_WANTS_FREEZER_CONTROL || BROKEN
+	depends on SUSPEND
+	default y
+	help
+	  This allows you to turn off the freezer for suspend. If this is
+	  done, no tasks are frozen for suspend to RAM/standby.
+
+	  Turning OFF this setting is NOT recommended! If in doubt, say Y.
+
 config HIBERNATION
 	bool "Hibernation (aka 'suspend to disk')"
 	depends on PM && SWAP && ARCH_HIBERNATION_POSSIBLE

kernel/power/main.c

@@ -181,7 +181,7 @@ static int suspend_prepare(void)
 
 	pm_prepare_console();
 
-	if (freeze_processes()) {
+	if (suspend_freeze_processes()) {
 		error = -EAGAIN;
 		goto Thaw;
 	}
@@ -199,7 +199,7 @@ static int suspend_prepare(void)
 		return 0;
 
  Thaw:
-	thaw_processes();
+	suspend_thaw_processes();
 	pm_restore_console();
  Finish:
 	pm_notifier_call_chain(PM_POST_SUSPEND);
@@ -308,7 +308,7 @@ int suspend_devices_and_enter(suspend_state_t state)
  */
 static void suspend_finish(void)
 {
-	thaw_processes();
+	suspend_thaw_processes();
 	pm_restore_console();
 	pm_notifier_call_chain(PM_POST_SUSPEND);
 }

kernel/power/power.h

 #include <linux/suspend.h>
 #include <linux/suspend_ioctls.h>
 #include <linux/utsname.h>
+#include <linux/freezer.h>
 
 struct swsusp_info {
 	struct new_utsname	uts;
@@ -203,3 +204,24 @@ enum {
 #define TEST_MAX	(__TEST_AFTER_LAST - 1)
 
 extern int pm_test_level;
+
+#ifdef CONFIG_SUSPEND_FREEZER
+static inline int suspend_freeze_processes(void)
+{
+	return freeze_processes();
+}
+
+static inline void suspend_thaw_processes(void)
+{
+	thaw_processes();
+}
+#else
+static inline int suspend_freeze_processes(void)
+{
+	return 0;
+}
+
+static inline void suspend_thaw_processes(void)
+{
+}
+#endif