Commit d728b1e6 authored by David Brownell's avatar David Brownell Committed by Linus Torvalds
Browse files

[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: default avatarDavid Brownell <dbrownell@users.sourceforge.net>
Acked-by: default avatarAlessandro Zummo <a.zummo@towertech.it>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 2601a464

drivers/rtc/interface.c

+11 −4
Original line number Diff line number Diff line
@@ -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);

drivers/rtc/rtc-at91.c

+2 −1
Original line number Diff line number Diff line
@@ -292,7 +292,8 @@ static int __init at91_rtc_probe(struct platform_device *pdev) 
					AT91_RTC_CALEV);



	ret = request_irq(AT91_ID_SYS, at91_rtc_interrupt,

				IRQF_SHARED, "at91_rtc", pdev);

				IRQF_DISABLED | IRQF_SHARED,

				"at91_rtc", pdev);

	if (ret) {

		printk(KERN_ERR "at91_rtc: IRQ %d already in use.\n",

				AT91_ID_SYS);

drivers/rtc/rtc-dev.c

+7 −5
Original line number Diff line number Diff line
@@ -61,7 +61,9 @@ static void rtc_uie_task(void *data) 
	int err;



	err = rtc_read_time(&rtc->class_dev, &tm);

	spin_lock_irq(&rtc->irq_lock);



	local_irq_disable();

	spin_lock(&rtc->irq_lock);

	if (rtc->stop_uie_polling || err) {

		rtc->uie_task_active = 0;

	} else if (rtc->oldsecs != tm.tm_sec) {
@@ -74,11 +76,11 @@ static void rtc_uie_task(void *data) 
	} else if (schedule_work(&rtc->uie_task) == 0) {

		rtc->uie_task_active = 0;

	}

	spin_unlock_irq(&rtc->irq_lock);

	spin_unlock(&rtc->irq_lock);

	if (num)

		rtc_update_irq(&rtc->class_dev, num, RTC_UF | RTC_IRQF);

	local_irq_enable();

}



static void rtc_uie_timer(unsigned long data)

{

	struct rtc_device *rtc = (struct rtc_device *)data;
@@ -238,10 +240,10 @@ static int rtc_dev_ioctl(struct inode *inode, struct file *file, 


	/* avoid conflicting IRQ users */

	if (cmd == RTC_PIE_ON || cmd == RTC_PIE_OFF || cmd == RTC_IRQP_SET) {

		spin_lock(&rtc->irq_task_lock);

		spin_lock_irq(&rtc->irq_task_lock);

		if (rtc->irq_task)

			err = -EBUSY;

		spin_unlock(&rtc->irq_task_lock);

		spin_unlock_irq(&rtc->irq_task_lock);



		if (err < 0)

			return err;

drivers/rtc/rtc-ds1553.c

+2 −1
Original line number Diff line number Diff line
@@ -340,7 +340,8 @@ static int __init ds1553_rtc_probe(struct platform_device *pdev) 


	if (pdata->irq >= 0) {

		writeb(0, ioaddr + RTC_INTERRUPTS);

		if (request_irq(pdata->irq, ds1553_rtc_interrupt, IRQF_SHARED,

		if (request_irq(pdata->irq, ds1553_rtc_interrupt,

				IRQF_DISABLED | IRQF_SHARED,

				pdev->name, pdev) < 0) {

			dev_warn(&pdev->dev, "interrupt not available.\n");

			pdata->irq = -1;

drivers/rtc/rtc-test.c

+2 −0
Original line number Diff line number Diff line
@@ -99,6 +99,7 @@ static ssize_t test_irq_store(struct device *dev, 
	struct rtc_device *rtc = platform_get_drvdata(plat_dev);



	retval = count;

	local_irq_disable();

	if (strncmp(buf, "tick", 4) == 0)

		rtc_update_irq(&rtc->class_dev, 1, RTC_PF | RTC_IRQF);

	else if (strncmp(buf, "alarm", 5) == 0)
@@ -107,6 +108,7 @@ static ssize_t test_irq_store(struct device *dev, 
		rtc_update_irq(&rtc->class_dev, 1, RTC_UF | RTC_IRQF);

	else

		retval = -EINVAL;

	local_irq_enable();



	return retval;

}

CRA Git | Maintained and supported by SUSTech CRA and CCSE