[PATCH] rtc class locking bugfixes

I got a lockdep warning when running "rtctest" so I though it'd be good
to see what was up.

 - The warning was for rtc->irq_task_lock, gotten from rtc_update_irq()
   by irq handlerss ... but in a handful of other cases, grabbed without
   blocking IRQs.

 - Some callers to rtc_update_irq() were not ensuring IRQs were blocked,
   yet the routine expects that; make sure all callers block IRQs.

It would appear that RTC API tests haven't been part of anyone's kernel
regression test suite recently, at least not with lockdep running.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Acked-by: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 11 insertions, 4 deletions

diff --git a/drivers/rtc/interface.c b/drivers/rtc/interface.c
index 4783ec68fb3c..6f11f6dfdd9d 100644
--- a/drivers/rtc/interface.c
+++ b/drivers/rtc/interface.c
@@ -145,6 +145,13 @@ int rtc_set_alarm(struct class_device *class_dev, struct rtc_wkalrm *alarm)
 }
 EXPORT_SYMBOL_GPL(rtc_set_alarm);
 
+/**
+ * rtc_update_irq - report RTC periodic, alarm, and/or update irqs
+ * @class_dev: the rtc's class device
+ * @num: how many irqs are being reported (usually one)
+ * @events: mask of RTC_IRQF with one or more of RTC_PF, RTC_AF, RTC_UF
+ * Context: in_interrupt(), irqs blocked
+ */
 void rtc_update_irq(struct class_device *class_dev,
                 unsigned long num, unsigned long events)
 {
@@ -201,12 +208,12 @@ int rtc_irq_register(struct class_device *class_dev, struct rtc_task *task)
         if (task == NULL || task->func == NULL)
                 return -EINVAL;
 
-        spin_lock(&rtc->irq_task_lock);
+        spin_lock_irq(&rtc->irq_task_lock);
         if (rtc->irq_task == NULL) {
                 rtc->irq_task = task;
                 retval = 0;
         }
-        spin_unlock(&rtc->irq_task_lock);
+        spin_unlock_irq(&rtc->irq_task_lock);
 
         return retval;
 }
@@ -216,10 +223,10 @@ void rtc_irq_unregister(struct class_device *class_dev, struct rtc_task *task)
 {
         struct rtc_device *rtc = to_rtc_device(class_dev);
 
-        spin_lock(&rtc->irq_task_lock);
+        spin_lock_irq(&rtc->irq_task_lock);
         if (rtc->irq_task == task)
                 rtc->irq_task = NULL;
-        spin_unlock(&rtc->irq_task_lock);
+        spin_unlock_irq(&rtc->irq_task_lock);
 }
 EXPORT_SYMBOL_GPL(rtc_irq_unregister);