[RFC][PATCH 2/3] Hibernation: New testing facility (rev. 2)

["Rafael J. Wysocki" <rjw@sisk.pl>]

From: Rafael J. Wysocki <rjw@sisk.pl>

Make it possible to test the hibernation core code with the help of the
/sys/power/pm_test attribute introduced for suspend testing in the previous
patch.

Writing an appropriate string to this file causes the hibernation code to work
in one of the test modes defined as follows:

freezer - test the freezing of processes
devices - test the freezing of processes and suspending of devices
platform - test the freezing of processes, suspending of devices and platform
           global control methods(*)
processors - test the freezing of processes, suspending of devices, platform
             global control methods(*) and the disabling of nonboot CPUs
core - test the freezing of processes, suspending of devices, platform global
       control methods(*), the disabling of nonboot CPUs and suspending of
       platform/system devices

(*) - the platform global control methods are only available on ACPI systems
      and are only tested if the hibernation mode is set to "platform"

Then, if a hibernation is started by normal means, the hibernation core will
perform its normal operations up to the point indicated by given test level.
Next, it will wait for 5 seconds and carry out the resume operations needed to
transition the system back to the fully functional state.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
---
 kernel/power/disk.c  |   70 ++++++++++++++++++++++++++++++++++++++++-----------
 kernel/power/power.h |    2 +
 2 files changed, 57 insertions(+), 15 deletions(-)

Index: linux-2.6/kernel/power/disk.c
===================================================================
--- linux-2.6.orig/kernel/power/disk.c
+++ linux-2.6/kernel/power/disk.c
@@ -70,6 +70,35 @@ void hibernation_set_ops(struct platform
 	mutex_unlock(&pm_mutex);
 }
 
+#ifdef CONFIG_PM_DEBUG
+static void hibernation_debug_sleep(void)
+{
+	printk(KERN_INFO "hibernation debug: Waiting for 5 seconds.\n");
+	mdelay(5000);
+}
+
+static int hibernation_testmode(int mode)
+{
+	if (hibernation_mode == mode) {
+		hibernation_debug_sleep();
+		return 1;
+	}
+	return 0;
+}
+
+static int hibernation_test(int level)
+{
+	if (pm_test_level == level) {
+		hibernation_debug_sleep();
+		return 1;
+	}
+	return 0;
+}
+#else /* !CONFIG_PM_DEBUG */
+static int hibernation_testmode(int mode) { return 0; }
+static int hibernation_test(int level) { return 0; }
+#endif /* !CONFIG_PM_DEBUG */
+
 /**
  *	platform_start - tell the platform driver that we're starting
  *	hibernation
@@ -167,6 +196,10 @@ int create_image(int platform_mode)
 		goto Enable_irqs;
 	}
 
+	if (hibernation_test(TEST_CORE))
+		goto Power_up;
+
+	in_suspend = 1;
 	save_processor_state();
 	error = swsusp_arch_suspend();
 	if (error)
@@ -175,6 +208,7 @@ int create_image(int platform_mode)
 	restore_processor_state();
 	if (!in_suspend)
 		platform_leave(platform_mode);
+ Power_up:
 	/* NOTE:  device_power_up() is just a resume() for devices
 	 * that suspended with irqs off ... no overall powerup.
 	 */
@@ -211,24 +245,29 @@ int hibernation_snapshot(int platform_mo
 	if (error)
 		goto Resume_console;
 
-	error = platform_pre_snapshot(platform_mode);
-	if (error)
+	if (hibernation_test(TEST_DEVICES))
 		goto Resume_devices;
 
+	error = platform_pre_snapshot(platform_mode);
+	if (error || hibernation_test(TEST_PLATFORM))
+		goto Finish;
+
 	error = disable_nonboot_cpus();
 	if (!error) {
-		if (hibernation_mode != HIBERNATION_TEST) {
-			in_suspend = 1;
-			error = create_image(platform_mode);
-			/* Control returns here after successful restore */
-		} else {
-			printk("swsusp debug: Waiting for 5 seconds.\n");
-			mdelay(5000);
-		}
+		if (hibernation_test(TEST_CPUS))
+			goto Enable_cpus;
+
+		if (hibernation_testmode(HIBERNATION_TEST))
+			goto Enable_cpus;
+
+		error = create_image(platform_mode);
+		/* Control returns here after successful restore */
 	}
+ Enable_cpus:
 	enable_nonboot_cpus();
- Resume_devices:
+ Finish:
 	platform_finish(platform_mode);
+ Resume_devices:
 	device_resume();
  Resume_console:
 	resume_console();
@@ -406,11 +445,12 @@ int hibernate(void)
 	if (error)
 		goto Finish;
 
-	if (hibernation_mode == HIBERNATION_TESTPROC) {
-		printk("swsusp debug: Waiting for 5 seconds.\n");
-		mdelay(5000);
+	if (hibernation_test(TEST_FREEZER))
 		goto Thaw;
-	}
+
+	if (hibernation_testmode(HIBERNATION_TESTPROC))
+		goto Thaw;
+
 	error = hibernation_snapshot(hibernation_mode == HIBERNATION_PLATFORM);
 	if (in_suspend && !error) {
 		unsigned int flags = 0;
Index: linux-2.6/kernel/power/power.h
===================================================================
--- linux-2.6.orig/kernel/power/power.h
+++ linux-2.6/kernel/power/power.h
@@ -208,3 +208,5 @@ enum {
 
 #define TEST_FIRST	TEST_NONE
 #define TEST_MAX	(__TEST_AFTER_LAST - 1)
+
+extern int pm_test_level;