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

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
...@@ -293,7 +293,7 @@ int rtc_irq_register(struct rtc_device *rtc, struct rtc_task *task) ...@@ -293,7 +293,7 @@ int rtc_irq_register(struct rtc_device *rtc, struct rtc_task *task)
return -EINVAL; return -EINVAL;
/* Cannot register while the char dev is in use */ /* 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; return -EBUSY;
spin_lock_irq(&rtc->irq_task_lock); spin_lock_irq(&rtc->irq_task_lock);
...@@ -303,7 +303,7 @@ int rtc_irq_register(struct rtc_device *rtc, struct rtc_task *task) ...@@ -303,7 +303,7 @@ int rtc_irq_register(struct rtc_device *rtc, struct rtc_task *task)
} }
spin_unlock_irq(&rtc->irq_task_lock); spin_unlock_irq(&rtc->irq_task_lock);
mutex_unlock(&rtc->char_lock); clear_bit(RTC_DEV_BUSY, &rtc->flags);
return retval; return retval;
} }
......
...@@ -26,10 +26,7 @@ static int rtc_dev_open(struct inode *inode, struct file *file) ...@@ -26,10 +26,7 @@ static int rtc_dev_open(struct inode *inode, struct file *file)
struct rtc_device, char_dev); struct rtc_device, char_dev);
const struct rtc_class_ops *ops = rtc->ops; const struct rtc_class_ops *ops = rtc->ops;
/* We keep the lock as long as the device is in use if (test_and_set_bit(RTC_DEV_BUSY, &rtc->flags))
* and return immediately if busy
*/
if (!(mutex_trylock(&rtc->char_lock)))
return -EBUSY; return -EBUSY;
file->private_data = rtc; file->private_data = rtc;
...@@ -43,8 +40,8 @@ static int rtc_dev_open(struct inode *inode, struct file *file) ...@@ -43,8 +40,8 @@ static int rtc_dev_open(struct inode *inode, struct file *file)
return 0; return 0;
} }
/* something has gone wrong, release the lock */ /* something has gone wrong */
mutex_unlock(&rtc->char_lock); clear_bit(RTC_DEV_BUSY, &rtc->flags);
return err; return err;
} }
...@@ -405,7 +402,7 @@ static int rtc_dev_release(struct inode *inode, struct file *file) ...@@ -405,7 +402,7 @@ static int rtc_dev_release(struct inode *inode, struct file *file)
if (rtc->ops->release) if (rtc->ops->release)
rtc->ops->release(rtc->dev.parent); rtc->ops->release(rtc->dev.parent);
mutex_unlock(&rtc->char_lock); clear_bit(RTC_DEV_BUSY, &rtc->flags);
return 0; return 0;
} }
...@@ -440,7 +437,6 @@ void rtc_dev_prepare(struct rtc_device *rtc) ...@@ -440,7 +437,6 @@ void rtc_dev_prepare(struct rtc_device *rtc)
rtc->dev.devt = MKDEV(MAJOR(rtc_devt), rtc->id); rtc->dev.devt = MKDEV(MAJOR(rtc_devt), rtc->id);
mutex_init(&rtc->char_lock);
#ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL #ifdef CONFIG_RTC_INTF_DEV_UIE_EMUL
INIT_WORK(&rtc->uie_task, rtc_uie_task); INIT_WORK(&rtc->uie_task, rtc_uie_task);
setup_timer(&rtc->uie_timer, rtc_uie_timer, (unsigned long)rtc); setup_timer(&rtc->uie_timer, rtc_uie_timer, (unsigned long)rtc);
......
...@@ -133,6 +133,9 @@ struct rtc_class_ops { ...@@ -133,6 +133,9 @@ struct rtc_class_ops {
#define RTC_DEVICE_NAME_SIZE 20 #define RTC_DEVICE_NAME_SIZE 20
struct rtc_task; struct rtc_task;
/* flags */
#define RTC_DEV_BUSY 0
struct rtc_device struct rtc_device
{ {
struct device dev; struct device dev;
...@@ -145,7 +148,7 @@ struct rtc_device ...@@ -145,7 +148,7 @@ struct rtc_device
struct mutex ops_lock; struct mutex ops_lock;
struct cdev char_dev; struct cdev char_dev;
struct mutex char_lock; unsigned long flags;
unsigned long irq_data; unsigned long irq_data;
spinlock_t irq_lock; spinlock_t irq_lock;
......
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