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>
diff --git a/drivers/rtc/interface.c b/drivers/rtc/interface.c
index de0da54..a4f56e9 100644
--- a/drivers/rtc/interface.c
+++ b/drivers/rtc/interface.c
@@ -293,7 +293,7 @@
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 @@
}
spin_unlock_irq(&rtc->irq_task_lock);
- mutex_unlock(&rtc->char_lock);
+ clear_bit(RTC_DEV_BUSY, &rtc->flags);
return retval;
}