Re: [PATCH] PM: Prevent dpm_prepare() from returning errors unnecessarily

Rafael J. Wysocki
2010-12-01T23:51:26Z

On Wednesday, December 01, 2010, Alan Stern wrote:
> On Tue, 30 Nov 2010, Rafael J. Wysocki wrote:
>
> > > Provided you repair the error that Lei Ming pointed out. That's the
> > > problem with functions that return Boolean values -- you have to name
> > > them very carefully. Ideally the name should be a predicate or a
> > > question.
> >
> > I already have fixed it.
> >
> > The name is unfortunate indeed, perhaps it's better to call that function
> > pm_new_wakeup_events() or something like this.
>
> Or pm_any_wakeup_events(). And reverse the meaning of the return
> value, of course -- it would be good to explain the return value in
> the kerneldoc.

OK, so please let me know what you think of the appended patch (on top of the
previous one).

Thanks,
Rafael

---
From: Rafael J. Wysocki <rjw@sisk.pl>
Subject: PM / Wakeup: Replace pm_check_wakeup_events() with pm_wakeup_pending()

To avoid confusion with the meaning and return value of
pm_check_wakeup_events() replace it with pm_wakeup_pending() that
will work the other way around (ie. return true when system-wide
power transition should be aborted).

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
---
drivers/base/power/main.c | 2 +-
drivers/base/power/wakeup.c | 20 ++++++++++----------
include/linux/suspend.h | 4 ++--
kernel/power/hibernate.c | 4 ++--
kernel/power/process.c | 2 +-
kernel/power/suspend.c | 2 +-
6 files changed, 17 insertions(+), 17 deletions(-)

Index: linux-2.6/drivers/base/power/wakeup.c
===================================================================
--- linux-2.6.orig/drivers/base/power/wakeup.c
+++ linux-2.6/drivers/base/power/wakeup.c
@@ -542,26 +542,26 @@ static void pm_wakeup_update_hit_counts(
}

/**
- * pm_check_wakeup_events - Check for new wakeup events.
+ * pm_wakeup_pending - Check if power transition in progress should be aborted.
*
* Compare the current number of registered wakeup events with its preserved
- * value from the past to check if new wakeup events have been registered since
- * the old value was stored. Check if the current number of wakeup events being
- * processed is zero.
+ * value from the past and return true if new wakeup events have been registered
+ * since the old value was stored. Also return true if the current number of
+ * wakeup events being processed is different from zero.
*/
-bool pm_check_wakeup_events(void)
+bool pm_wakeup_pending(void)
{
unsigned long flags;
- bool ret = true;
+ bool ret = false;

spin_lock_irqsave(&events_lock, flags);
if (events_check_enabled) {
- ret = ((unsigned int)atomic_read(&event_count) == saved_count)
- && !atomic_read(&events_in_progress);
- events_check_enabled = ret;
+ ret = ((unsigned int)atomic_read(&event_count) != saved_count)
+ || atomic_read(&events_in_progress);
+ events_check_enabled = !ret;
}
spin_unlock_irqrestore(&events_lock, flags);
- if (!ret)
+ if (ret)
pm_wakeup_update_hit_counts();
return ret;
}
Index: linux-2.6/include/linux/suspend.h
===================================================================
--- linux-2.6.orig/include/linux/suspend.h
+++ linux-2.6/include/linux/suspend.h
@@ -292,7 +292,7 @@ extern int unregister_pm_notifier(struct
/* drivers/base/power/wakeup.c */
extern bool events_check_enabled;

-extern bool pm_check_wakeup_events(void);
+extern bool pm_wakeup_pending(void);
extern bool pm_get_wakeup_count(unsigned int *count);
extern bool pm_save_wakeup_count(unsigned int count);
#else /* !CONFIG_PM_SLEEP */
@@ -309,7 +309,7 @@ static inline int unregister_pm_notifier

#define pm_notifier(fn, pri) do { (void)(fn); } while (0)

-static inline bool pm_check_wakeup_events(void) { return true; }
+static inline bool pm_wakeup_pending(void) { return true; }
#endif /* !CONFIG_PM_SLEEP */

extern struct mutex pm_mutex;
Index: linux-2.6/drivers/base/power/main.c
===================================================================
--- linux-2.6.orig/drivers/base/power/main.c
+++ linux-2.6/drivers/base/power/main.c
@@ -1056,7 +1056,7 @@ static int dpm_prepare(pm_message_t stat
if (pm_runtime_barrier(dev) && device_may_wakeup(dev))
pm_wakeup_event(dev, 0);

- if (!pm_check_wakeup_events()) {
+ if (pm_wakeup_pending()) {
pm_runtime_put_sync(dev);
error = -EBUSY;
} else {
Index: linux-2.6/kernel/power/hibernate.c
===================================================================
--- linux-2.6.orig/kernel/power/hibernate.c
+++ linux-2.6/kernel/power/hibernate.c
@@ -278,7 +278,7 @@ static int create_image(int platform_mod
goto Enable_irqs;
}

- if (hibernation_test(TEST_CORE) || !pm_check_wakeup_events())
+ if (hibernation_test(TEST_CORE) || pm_wakeup_pending())
goto Power_up;

in_suspend = 1;
@@ -516,7 +516,7 @@ int hibernation_platform_enter(void)

local_irq_disable();
sysdev_suspend(PMSG_HIBERNATE);
- if (!pm_check_wakeup_events()) {
+ if (pm_wakeup_pending()) {
error = -EAGAIN;
goto Power_up;
}
Index: linux-2.6/kernel/power/process.c
===================================================================
--- linux-2.6.orig/kernel/power/process.c
+++ linux-2.6/kernel/power/process.c
@@ -85,7 +85,7 @@ static int try_to_freeze_tasks(bool sig_
if (!todo || time_after(jiffies, end_time))
break;

- if (!pm_check_wakeup_events()) {
+ if (pm_wakeup_pending()) {
wakeup = true;
break;
}
Index: linux-2.6/kernel/power/suspend.c
===================================================================
--- linux-2.6.orig/kernel/power/suspend.c
+++ linux-2.6/kernel/power/suspend.c
@@ -163,7 +163,7 @@ static int suspend_enter(suspend_state_t

error = sysdev_suspend(PMSG_SUSPEND);
if (!error) {
- if (!suspend_test(TEST_CORE) && pm_check_wakeup_events()) {
+ if (!(suspend_test(TEST_CORE) || pm_wakeup_pending())) {
error = suspend_ops->enter(state);
events_check_enabled = false;
}