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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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