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Subject[PATCH 1/6] [RFC] suspend: Block suspend when wakeups are in-progress
Date
With the current pm_stay_awake/pm_relax api, reads to
/sys/power/wakeup_count will block when pm_stay_awake() has been
called. Then once pm_relax() returns, the read will unblock and return
the wakeup_count value. This value can be echo'ed back into wakeup_count,
and if no other wakeup events have occured, the system can be suspended
by calling "echo mem > /sys/power/state".
This method is somewhat advisory, as if a wakeup event has occured
between the reading of /sys/power/wakeup_count and the attempt to suspend,
that attempt to suspend will fail. However, if a second attmept to suspend
is tried, without checking /sys/power/wakeup_count, the suspend will
succeed.

Similarly, if pm_stay_awake() has been called, and then a suspend is
attepted wihtout checking /sys/power/wakeup_count, the suspend will
succeed, despite the pm_relax() call not having been made.

This patch tries to make the pm_stay_awake() call a bit more enforcing,
such that any attempt to suspend that occurs while a wakeup is in progress
will fail. Once the matching pm_relax() has been called, suspend will
succeed.

This does not change the blocking behavior of /sys/power/wakeup_count,
or the suspend failure if a stale wakeup count has been echo'ed into
the /sys/power/wakeup_count.

Also modified the hibernate path in the same way.

CC: Rafael J. Wysocki <rjw@sisk.pl>
CC: arve@android.com
CC: markgross@thegnar.org
CC: Alan Stern <stern@rowland.harvard.edu>
CC: amit.kucheria@linaro.org
CC: farrowg@sg.ibm.com
CC: Dmitry Fink (Palm GBU) <Dmitry.Fink@palm.com>
CC: linux-pm@lists.linux-foundation.org
CC: khilman@ti.com
CC: Magnus Damm <damm@opensource.se>
CC: mjg@redhat.com
CC: peterz@infradead.org
Signed-off-by: John Stultz <john.stultz@linaro.org>
---
drivers/base/power/wakeup.c | 13 +++++++++++++
include/linux/suspend.h | 3 +++
kernel/power/hibernate.c | 5 +++++
kernel/power/suspend.c | 5 +++++
4 files changed, 26 insertions(+), 0 deletions(-)
diff --git a/drivers/base/power/wakeup.c b/drivers/base/power/wakeup.c
index 84f7c7d..0722873 100644
--- a/drivers/base/power/wakeup.c
+++ b/drivers/base/power/wakeup.c
@@ -580,6 +580,19 @@ static void pm_wakeup_update_hit_counts(void)
rcu_read_unlock();
}

+
+bool pm_wakeup_in_progress(void)
+{
+ unsigned int cnt, inpr;
+ unsigned long flags;
+
+ spin_lock_irqsave(&events_lock, flags);
+ split_counters(&cnt, &inpr);
+ spin_unlock_irqrestore(&events_lock, flags);
+
+ return (inpr != 0);
+}
+
/**
* pm_wakeup_pending - Check if power transition in progress should be aborted.
*
diff --git a/include/linux/suspend.h b/include/linux/suspend.h
index 6bbcef2..c9403a1 100644
--- a/include/linux/suspend.h
+++ b/include/linux/suspend.h
@@ -294,6 +294,7 @@ extern int unregister_pm_notifier(struct notifier_block *nb);
extern bool events_check_enabled;

extern bool pm_wakeup_pending(void);
+extern bool pm_wakeup_in_progress(void);
extern bool pm_get_wakeup_count(unsigned int *count);
extern bool pm_save_wakeup_count(unsigned int count);
#else /* !CONFIG_PM_SLEEP */
@@ -311,6 +312,8 @@ static inline int unregister_pm_notifier(struct notifier_block *nb)
#define pm_notifier(fn, pri) do { (void)(fn); } while (0)

static inline bool pm_wakeup_pending(void) { return false; }
+static inline bool pm_wakeup_in_progress(void) { return false; }
+
#endif /* !CONFIG_PM_SLEEP */

extern struct mutex pm_mutex;
diff --git a/kernel/power/hibernate.c b/kernel/power/hibernate.c
index 8f7b1db..22dc22c 100644
--- a/kernel/power/hibernate.c
+++ b/kernel/power/hibernate.c
@@ -611,6 +611,11 @@ int hibernate(void)
goto Unlock;
}

+ if (pm_wakeup_in_progress()) {
+ error = -EBUSY;
+ goto Unlock;
+ }
+
pm_prepare_console();
error = pm_notifier_call_chain(PM_HIBERNATION_PREPARE);
if (error)
diff --git a/kernel/power/suspend.c b/kernel/power/suspend.c
index b6b71ad..b2dba52 100644
--- a/kernel/power/suspend.c
+++ b/kernel/power/suspend.c
@@ -281,6 +281,11 @@ int enter_state(suspend_state_t state)
if (!mutex_trylock(&pm_mutex))
return -EBUSY;

+ if (pm_wakeup_in_progress()) {
+ error = -EBUSY;
+ goto Unlock;
+ }
+
printk(KERN_INFO "PM: Syncing filesystems ... ");
sys_sync();
printk("done.\n");
--
1.7.3.2.146.gca209


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