Techwizz/kernel-fxtec-pro1x
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RTC: convert mutex to bitfield

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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: Jiri Kosina <jkosina@suse.cz>
Acked-by: Alessandro Zummo <a.zummo@towertech.it>
Cc: David Brownell <david-b@pacbell.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Jiri Kosina 2007-11-28 16:22:03 -08:00 committed by Linus Torvalds
parent 08b633070a
commit 8853c202b4
3 changed files with 10 additions and 11 deletions
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4
drivers/rtc/interface.c
View file

@ -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;
}

12
drivers/rtc/rtc-dev.c
View file

@ -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);

5
include/linux/rtc.h
View file

@ -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;