From: Rafael J. Wysocki
Subject: [RFC][PATCH 0/3] Suspend and hibernation test facility
Date: Nov 1, 3:57 pm 2007

Hi,

The following patches add a new testing facility for suspend and hibernation.

The first patch adds the possibility to test the suspend (STD) core code
without actually suspending, which is useful for tracking problems with drivers
etc.

The second one modifies the hibernation core so that it can use the same
facility (it's a bit more powerful than the existing hibernation test modes,
since they really can't test the ACPI global methods).

The third one modified documentation in accordance with the two previous ones.

Comments welcome.

Greetings,
Rafael


-- 
"Premature optimization is the root of all evil." - Donald Knuth

-

From: Rafael J. Wysocki
Subject: [RFC][PATCH 1/3] Suspend: Testing facility
Date: Nov 1, 3:58 pm 2007

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

Introduce /sys/power/pm_test_level attribute allowing one to test the suspend
core code.  Namely, writing a number (1-5) to this file causes the suspend code
to work in one of the test modes defined as follows:

5 - test the freezing of processes
4 - test the freezing of processes and suspending of devices
3 - test the freezing of processes, suspending of devices and platform global
    control methods
2 - test the freezing of processes, suspending of devices, platform global
    control methods and the disabling of nonboot CPUs
1 - test the freezing of processes, suspending of devices, platform global
    control methods, the disabling of nonboot CPUs and suspending of
    platform/system devices

Then, if a suspend is started by normal means, the suspend core will perform
its normal operations up to the point indicated by the 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.

Writing 0 to /sys/power/pm_test_level turns the testing off.  The current test
level may be read from /sys/power/pm_test_level .

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
---
 kernel/power/main.c  |   75 ++++++++++++++++++++++++++++++++++++++++++++-------
 kernel/power/power.h |   10 ++++++
 2 files changed, 76 insertions(+), 9 deletions(-)

Index: linux-2.6/kernel/power/main.c
===================================================================
--- linux-2.6.orig/kernel/power/main.c
+++ linux-2.6/kernel/power/main.c
@@ -28,6 +28,46 @@ BLOCKING_NOTIFIER_HEAD(pm_chain_head);
 
 DEFINE_MUTEX(pm_mutex);
 
+#ifdef CONFIG_PM_DEBUG
+int pm_test_level = TEST_NONE;
+
+static int suspend_test(int level)
+{
+	if (pm_test_level == level) {
+		printk(KERN_INFO "suspend debug: Waiting for 5 seconds.\n");
+		mdelay(5000);
+		return 1;
+	}
+	return 0;
+}
+
+static ssize_t pm_test_level_show(struct kset *kset, char *buf)
+{
+	return sprintf(buf, "%d\n", pm_test_level);
+}
+
+static ssize_t
+pm_test_level_store(struct kset *kset, const char *buf, size_t n)
+{
+	int val;
+
+	if (sscanf(buf, "%d", &val) != 1)
+		return -EINVAL;
+
+	if (val < TEST_NONE || val > TEST_FREEZER)
+		return -EINVAL;
+
+	pm_test_level = val;
+
+	return n;
+}
+
+power_attr(pm_test_level);
+#else /* !CONFIG_PM_DEBUG */
+static inline int suspend_test(int level) { return 0; }
+#endif /* !CONFIG_PM_DEBUG */
+
+
 #ifdef CONFIG_SUSPEND
 
 /* This is just an arbitrary number */
@@ -133,7 +173,10 @@ static int suspend_enter(suspend_state_t
 		printk(KERN_ERR "Some devices failed to power down\n");
 		goto Done;
 	}
-	error = suspend_ops->enter(state);
+
+	if (!suspend_test(TEST_CORE))
+		error = suspend_ops->enter(state);
+
 	device_power_up();
  Done:
 	arch_suspend_enable_irqs();
@@ -164,16 +207,25 @@ int suspend_devices_and_enter(suspend_st
 		printk(KERN_ERR "Some devices failed to suspend\n");
 		goto Resume_console;
 	}
+
+	if (suspend_test(TEST_DEVICES))
+		goto Resume_devices;
+
 	if (suspend_ops->prepare) {
 		error = suspend_ops->prepare();
 		if (error)
 			goto Resume_devices;
 	}
+
+	if (suspend_test(TEST_PLATFORM))
+		goto Finish;
+
 	error = disable_nonboot_cpus();
-	if (!error)
+	if (!error && !suspend_test(TEST_CPUS))
 		suspend_enter(state);
 
 	enable_nonboot_cpus();
+ Finish:
 	if (suspend_ops->finish)
 		suspend_ops->finish();
  Resume_devices:
@@ -240,12 +292,17 @@ static int enter_state(suspend_state_t s
 	printk("done.\n");
 
 	pr_debug("PM: Preparing system for %s sleep\n", pm_states[state]);
-	if ((error = suspend_prepare()))
+	error = suspend_prepare();
+	if (error)
 		goto Unlock;
 
+	if (suspend_test(TEST_FREEZER))
+		goto Finish;
+
 	pr_debug("PM: Entering %s sleep\n", pm_states[state]);
 	error = suspend_devices_and_enter(state);
 
+ Finish:
 	pr_debug("PM: Finishing wakeup.\n");
 	suspend_finish();
  Unlock:
@@ -363,18 +420,18 @@ pm_trace_store(struct kset *kset, const 
 }
 
 power_attr(pm_trace);
+#endif /* CONFIG_PM_TRACE */
 
 static struct attribute * g[] = {
 	&state_attr.attr,
+#ifdef CONFIG_PM_TRACE
 	&pm_trace_attr.attr,
+#endif
+#ifdef CONFIG_PM_DEBUG
+	&pm_test_level_attr.attr,
+#endif
 	NULL,
 };
-#else
-static struct attribute * g[] = {
-	&state_attr.attr,
-	NULL,
-};
-#endif /* CONFIG_PM_TRACE */
 
 static struct attribute_group attr_group = {
 	.attrs = g,
Index: linux-2.6/kernel/power/power.h
===================================================================
--- linux-2.6.orig/kernel/power/power.h
+++ linux-2.6/kernel/power/power.h
@@ -182,3 +182,13 @@ static inline int pm_notifier_call_chain
 	return (blocking_notifier_call_chain(&pm_chain_head, val, NULL)
 			== NOTIFY_BAD) ? -EINVAL : 0;
 }
+
+/* Suspend test levels */
+enum {
+	TEST_NONE,
+	TEST_CORE,
+	TEST_CPUS,
+	TEST_PLATFORM,
+	TEST_DEVICES,
+	TEST_FREEZER
+};

-


From: Rafael J. Wysocki
Subject: [RFC][PATCH 2/3] Hibernation: New testing facility
Date: Nov 1, 3:59 pm 2007

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_level attribute introduced for suspend testing in the
previous patch.

Writing a number (1-5) to this file causes the hibernation code to work in one
of the test modes defined as follows:

5 - test the freezing of processes
4 - test the freezing of processes and suspending of devices
3 - test the freezing of processes, suspending of devices and platform global
    control methods(*)
2 - test the freezing of processes, suspending of devices, platform global
    control methods(*) and the disabling of nonboot CPUs
1 - 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 the 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
@@ -192,3 +192,5 @@ enum {
 	TEST_DEVICES,
 	TEST_FREEZER
 };
+
+extern int pm_test_level;

-