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>

1 files changed, 4 insertions, 1 deletions

diff --git a/include/linux/rtc.h b/include/linux/rtc.h
index 6d5e4a46781e..f2d0d1527721 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;