Commit 8853c202 authored by Jiri Kosina's avatar Jiri Kosina Committed by Linus Torvalds
Browse files

RTC: convert mutex to bitfield 



RTC code is using mutex to assure exclusive access to /dev/rtc.  This is
however wrong usage, as it leaves the mutex locked when returning into
userspace, which is unacceptable.

Convert rtc->char_lock into bit operation.

Signed-off-by: default avatarJiri Kosina <jkosina@suse.cz>
Acked-by: default avatarAlessandro Zummo <a.zummo@towertech.it>
Cc: David Brownell <david-b@pacbell.net>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 08b63307

drivers/rtc/interface.c

+2 −2
Original line number Diff line number Diff line
@@ -293,7 +293,7 @@ int rtc_irq_register(struct rtc_device *rtc, struct rtc_task *task) 
		return -EINVAL;



	/* Cannot register while the char dev is in use */

	if (!(mutex_trylock(&rtc->char_lock)))

	if (test_and_set_bit(RTC_DEV_BUSY, &rtc->flags))

		return -EBUSY;



	spin_lock_irq(&rtc->irq_task_lock);
@@ -303,7 +303,7 @@ int rtc_irq_register(struct rtc_device *rtc, struct rtc_task *task) 
	}

	spin_unlock_irq(&rtc->irq_task_lock);



	mutex_unlock(&rtc->char_lock);

	clear_bit(RTC_DEV_BUSY, &rtc->flags);



	return retval;

}

drivers/rtc/rtc-dev.c

+4 −8
Original line number Diff line number Diff line
@@ -26,10 +26,7 @@ static int rtc_dev_open(struct inode *inode, struct file *file) 
					struct rtc_device, char_dev);

	const struct rtc_class_ops *ops = rtc->ops;



	/* We keep the lock as long as the device is in use

	 * and return immediately if busy

	 */

	if (!(mutex_trylock(&rtc->char_lock)))

	if (test_and_set_bit(RTC_DEV_BUSY, &rtc->flags))

		return -EBUSY;



	file->private_data = rtc;
@@ -43,8 +40,8 @@ static int rtc_dev_open(struct inode *inode, struct file *file) 
		return 0;

	}



	/* something has gone wrong, release the lock */

	mutex_unlock(&rtc->char_lock);

	/* something has gone wrong */

	clear_bit(RTC_DEV_BUSY, &rtc->flags);

	return err;

}
@@ -405,7 +402,7 @@ static int rtc_dev_release(struct inode *inode, struct file *file) 
	if (rtc->ops->release)

		rtc->ops->release(rtc->dev.parent);



	mutex_unlock(&rtc->char_lock);

	clear_bit(RTC_DEV_BUSY, &rtc->flags);

	return 0;

}
@@ -440,7 +437,6 @@ void rtc_dev_prepare(struct rtc_device *rtc) 


	rtc->dev.devt = MKDEV(MAJOR(rtc_devt), rtc->id);



	mutex_init(&rtc->char_lock);

#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);

include/linux/rtc.h

+4 −1
Original line number Diff line number Diff line
@@ -133,6 +133,9 @@ struct rtc_class_ops { 
#define RTC_DEVICE_NAME_SIZE 20

struct rtc_task;



/* flags */

#define RTC_DEV_BUSY 0



struct rtc_device

{

	struct device dev;
@@ -145,7 +148,7 @@ struct rtc_device 
	struct mutex ops_lock;



	struct cdev char_dev;

	struct mutex char_lock;

	unsigned long flags;



	unsigned long irq_data;

	spinlock_t irq_lock;

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