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 <r...@sisk.pl> Cc: Android Team <kernel-t...@android.com> Cc: Arve Hjønnevåg <a...@android.com> Cc: Jon Medhurst (Tixy) <t...@linaro.org> Reported-and-debugged-by: Jon Medhurst (Tixy) <t...@linaro.org> Signed-off-by: John Stultz <john.stu...@linaro.org> --- 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; } -- 1.7.9.5 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
