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Subject[RFC][PATCH 1/3] Suspend: Testing facility
Date
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
+};
-
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