RTC: periodic irq fix

Add kernel/kernel and kernel/user locking for the periodic irq feature of
the rtc class.

PIE ioctls are also supported.

Signed-off-by: Alessandro Zummo <[e-mail]>
Cc: David Brownell <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

drivers/rtc/class.c

···
 	mutex_init(&rtc->ops_lock);
 	spin_lock_init(&rtc->irq_lock);
 	spin_lock_init(&rtc->irq_task_lock);
+	init_waitqueue_head(&rtc->irq_queue);
 
 	strlcpy(rtc->name, name, RTC_DEVICE_NAME_SIZE);
 	snprintf(rtc->dev.bus_id, BUS_ID_SIZE, "rtc%d", id);

drivers/rtc/interface.c

···
 	if (task == NULL || task->func == NULL)
 		return -EINVAL;
 
+	/* Cannot register while the char dev is in use */
+	if (!(mutex_trylock(&rtc->char_lock)))
+		return -EBUSY;
+
 	spin_lock_irq(&rtc->irq_task_lock);
 	if (rtc->irq_task == NULL) {
 		rtc->irq_task = task;
···
 	}
 	spin_unlock_irq(&rtc->irq_task_lock);
 
+	mutex_unlock(&rtc->char_lock);
+
 	return retval;
 }
 EXPORT_SYMBOL_GPL(rtc_irq_register);
 
 void rtc_irq_unregister(struct rtc_device *rtc, struct rtc_task *task)
 {
-
 	spin_lock_irq(&rtc->irq_task_lock);
 	if (rtc->irq_task == task)
 		rtc->irq_task = NULL;
···
 		return -ENXIO;
 
 	spin_lock_irqsave(&rtc->irq_task_lock, flags);
+	if (rtc->irq_task != NULL && task == NULL)
+		err = -EBUSY;
 	if (rtc->irq_task != task)
-		err = -ENXIO;
+		err = -EACCES;
 	spin_unlock_irqrestore(&rtc->irq_task_lock, flags);
 
 	if (err == 0)
···
 		return -ENXIO;
 
 	spin_lock_irqsave(&rtc->irq_task_lock, flags);
+	if (rtc->irq_task != NULL && task == NULL)
+		err = -EBUSY;
 	if (rtc->irq_task != task)
-		err = -ENXIO;
+		err = -EACCES;
 	spin_unlock_irqrestore(&rtc->irq_task_lock, flags);
 
 	if (err == 0) {

drivers/rtc/rtc-dev.c

···
 		break;
 	}
 
-	/* avoid conflicting IRQ users */
-	if (cmd == RTC_PIE_ON || cmd == RTC_PIE_OFF || cmd == RTC_IRQP_SET) {
-		spin_lock_irq(&rtc->irq_task_lock);
-		if (rtc->irq_task)
-			err = -EBUSY;
-		spin_unlock_irq(&rtc->irq_task_lock);
-
-		if (err < 0)
-			return err;
-	}
-
 	/* try the driver's ioctl interface */
 	if (ops->ioctl) {
 		err = ops->ioctl(rtc->dev.parent, cmd, arg);
···
 		err = rtc_set_time(rtc, &tm);
 		break;
 
-	case RTC_IRQP_READ:
-		if (ops->irq_set_freq)
-			err = put_user(rtc->irq_freq, (unsigned long __user *)uarg);
-		else
-			err = -ENOTTY;
+	case RTC_PIE_ON:
+		err = rtc_irq_set_state(rtc, NULL, 1);
+		break;
+
+	case RTC_PIE_OFF:
+		err = rtc_irq_set_state(rtc, NULL, 0);
 		break;
 
 	case RTC_IRQP_SET:
-		if (ops->irq_set_freq)
-			err = rtc_irq_set_freq(rtc, rtc->irq_task, arg);
-		else
-			err = -ENOTTY;
+		err = rtc_irq_set_freq(rtc, NULL, arg);
+		break;
+
+	case RTC_IRQP_READ:
+		err = put_user(rtc->irq_freq, (unsigned long __user *)uarg);
 		break;
 
 #if 0
···
 	rtc->dev.devt = MKDEV(MAJOR(rtc_devt), rtc->id);
 
 	mutex_init(&rtc->char_lock);
-	spin_lock_init(&rtc->irq_lock);
-	init_waitqueue_head(&rtc->irq_queue);
 #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
 	INIT_WORK(&rtc->uie_task, rtc_uie_task);
 	setup_timer(&rtc->uie_timer, rtc_uie_timer, (unsigned long)rtc);