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Subject[PATCH 2/3] PM / Wakeup: Make pm_save_wakeup_count() work as documented
Date
From: Rafael J. Wysocki <rjw@sisk.pl>

According to Documentation/ABI/testing/sysfs-power, the
/sys/power/wakeup_count interface should only make the kernel react
to wakeup events during suspend if the last write to it has been
successful. However, if /sys/power/wakeup_count is written to two
times in a row, where the first write is successful and the second
is not, the kernel will still react to wakeup events during suspend
due to a bug in pm_save_wakeup_count().

Fix the bug by making pm_save_wakeup_count() clear
events_check_enabled unconditionally before checking if there are
any new wakeup events registered since the previous read from
/sys/power/wakeup_count.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
---
drivers/base/power/wakeup.c | 13 ++++++-------
1 file changed, 6 insertions(+), 7 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
@@ -644,23 +644,22 @@ bool pm_get_wakeup_count(unsigned int *c
*
* If @count is equal to the current number of registered wakeup events and the
* current number of wakeup events being processed is zero, store @count as the
- * old number of registered wakeup events to be used by pm_check_wakeup_events()
- * and return true. Otherwise return false.
+ * old number of registered wakeup events for pm_check_wakeup_events(), enable
+ * wakeup events detection and return 'true'. Otherwise disable wakeup events
+ * detection and return 'false'.
*/
bool pm_save_wakeup_count(unsigned int count)
{
- bool ret = false;
-
+ events_check_enabled = false;
spin_lock_irq(&events_lock);
if (!__pm_wakeup_pending(count)) {
saved_count = count;
events_check_enabled = true;
- ret = true;
}
spin_unlock_irq(&events_lock);
- if (!ret)
+ if (!events_check_enabled)
pm_wakeup_update_hit_counts();
- return ret;
+ return events_check_enabled;
}

static struct dentry *wakeup_sources_stats_dentry;


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