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SubjectRe: [PATCH] wakeup: Use irqsave/irqrestore for events_lock
Date
On Thursday, September 06, 2012, John Stultz wrote:
> Jon Medhurst (Tixy) recently noticed a problem with the
> events_lock usage. One of the Android patches that uses
> wakeup_sources calls wakeup_source_add() with irqs disabled.
> However, the event_lock usage in wakeup_source_add() uses
> spin_lock_irq()/spin_unlock_irq(), which reenables interrupts.
> This results in lockdep warnings.
>
> The fix is to use spin_lock_irqsave()/spin_lock_irqrestore()
> instead for the events_lock.
>
> Full bug report here:
> https://bugs.launchpad.net/linaro-landing-team-arm/+bug/1037565
>
> Cc: Rafael J. Wysocki <rjw@sisk.pl>
> Cc: Android Team <kernel-team@android.com>
> Cc: Arve Hjønnevåg <arve@android.com>
> Cc: Jon Medhurst (Tixy) <tixy@linaro.org>
> Reported-and-debugged-by: Jon Medhurst (Tixy) <tixy@linaro.org>
> Signed-off-by: John Stultz <john.stultz@linaro.org>

Thanks, applied to the linux-next brach of the linux-pm.git tree as v3.7
material.

Please consider CCing PM-related patches to linux-pm@vger.kernel.org in the
future, that makes it much easier for me to handle them.

Thanks,
Rafael


> ---
> drivers/base/power/wakeup.c | 17 +++++++++++------
> 1 file changed, 11 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/base/power/wakeup.c b/drivers/base/power/wakeup.c
> index cbb463b..0e4b093 100644
> --- a/drivers/base/power/wakeup.c
> +++ b/drivers/base/power/wakeup.c
> @@ -127,6 +127,8 @@ EXPORT_SYMBOL_GPL(wakeup_source_destroy);
> */
> void wakeup_source_add(struct wakeup_source *ws)
> {
> + unsigned long flags;
> +
> if (WARN_ON(!ws))
> return;
>
> @@ -135,9 +137,9 @@ void wakeup_source_add(struct wakeup_source *ws)
> ws->active = false;
> ws->last_time = ktime_get();
>
> - spin_lock_irq(&events_lock);
> + spin_lock_irqsave(&events_lock, flags);
> list_add_rcu(&ws->entry, &wakeup_sources);
> - spin_unlock_irq(&events_lock);
> + spin_unlock_irqrestore(&events_lock, flags);
> }
> EXPORT_SYMBOL_GPL(wakeup_source_add);
>
> @@ -147,12 +149,14 @@ EXPORT_SYMBOL_GPL(wakeup_source_add);
> */
> void wakeup_source_remove(struct wakeup_source *ws)
> {
> + unsigned long flags;
> +
> if (WARN_ON(!ws))
> return;
>
> - spin_lock_irq(&events_lock);
> + spin_lock_irqsave(&events_lock, flags);
> list_del_rcu(&ws->entry);
> - spin_unlock_irq(&events_lock);
> + spin_unlock_irqrestore(&events_lock, flags);
> synchronize_rcu();
> }
> EXPORT_SYMBOL_GPL(wakeup_source_remove);
> @@ -723,15 +727,16 @@ bool pm_get_wakeup_count(unsigned int *count, bool block)
> bool pm_save_wakeup_count(unsigned int count)
> {
> unsigned int cnt, inpr;
> + unsigned long flags;
>
> events_check_enabled = false;
> - spin_lock_irq(&events_lock);
> + spin_lock_irqsave(&events_lock, flags);
> split_counters(&cnt, &inpr);
> if (cnt == count && inpr == 0) {
> saved_count = count;
> events_check_enabled = true;
> }
> - spin_unlock_irq(&events_lock);
> + spin_unlock_irqrestore(&events_lock, flags);
> return events_check_enabled;
> }
>
>

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