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authorJiri Kosina <jkosina@suse.cz>2007-11-28 16:22:03 -0800
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-11-29 09:24:54 -0800
commit8853c202b4a91713dbfb4d9b6e1c87cc2aa12392 (patch)
treea6c9621d3067eebc17c2ce53fa45e7513ee832a6
parent08b633070ad5fa17a837428a601c32cf3db6aafd (diff)
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: 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>
-rw-r--r--drivers/rtc/interface.c4
-rw-r--r--drivers/rtc/rtc-dev.c12
-rw-r--r--include/linux/rtc.h5
3 files changed, 10 insertions, 11 deletions
diff --git a/drivers/rtc/interface.c b/drivers/rtc/interface.c
index de0da545c7a..a4f56e95cf9 100644
--- a/drivers/rtc/interface.c
+++ b/drivers/rtc/interface.c
@@ -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;
}
diff --git a/drivers/rtc/rtc-dev.c b/drivers/rtc/rtc-dev.c
index 814583bd2fe..ae1bf177d62 100644
--- a/drivers/rtc/rtc-dev.c
+++ b/drivers/rtc/rtc-dev.c
@@ -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);
diff --git a/include/linux/rtc.h b/include/linux/rtc.h
index 6d5e4a46781..f2d0d152772 100644
--- a/include/linux/rtc.h
+++ b/include/linux/rtc.h
@@ -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;