From 372a302e9a892229206aafca0352584a745bc5f3 Mon Sep 17 00:00:00 2001 From: Jiri Kosina Date: Tue, 4 Dec 2007 23:45:05 -0800 Subject: [PATCH] RTC: assure proper memory ordering with respect to RTC_DEV_BUSY flag We must make sure that the RTC_DEV_BUSY flag has proper lock semantics, i.e. that the RTC_DEV_BUSY stores clearing the flag don't get reordered before the preceeding stores and loads and vice versa. Spotted by Nick Piggin. Signed-off-by: Jiri Kosina Cc: Nick Piggin Cc: David Brownell Acked-by: Alessandro Zummo Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/rtc/interface.c | 4 ++-- drivers/rtc/rtc-dev.c | 6 +++--- 2 files changed, 5 insertions(+), 5 deletions(-) diff --git a/drivers/rtc/interface.c b/drivers/rtc/interface.c index a4f56e9..f1e00ff 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 (test_and_set_bit(RTC_DEV_BUSY, &rtc->flags)) + if (test_and_set_bit_lock(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); - clear_bit(RTC_DEV_BUSY, &rtc->flags); + clear_bit_unlock(RTC_DEV_BUSY, &rtc->flags); return retval; } diff --git a/drivers/rtc/rtc-dev.c b/drivers/rtc/rtc-dev.c index ae1bf17..025c60a 100644 --- a/drivers/rtc/rtc-dev.c +++ b/drivers/rtc/rtc-dev.c @@ -26,7 +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; - if (test_and_set_bit(RTC_DEV_BUSY, &rtc->flags)) + if (test_and_set_bit_lock(RTC_DEV_BUSY, &rtc->flags)) return -EBUSY; file->private_data = rtc; @@ -41,7 +41,7 @@ static int rtc_dev_open(struct inode *inode, struct file *file) } /* something has gone wrong */ - clear_bit(RTC_DEV_BUSY, &rtc->flags); + clear_bit_unlock(RTC_DEV_BUSY, &rtc->flags); return err; } @@ -402,7 +402,7 @@ static int rtc_dev_release(struct inode *inode, struct file *file) if (rtc->ops->release) rtc->ops->release(rtc->dev.parent); - clear_bit(RTC_DEV_BUSY, &rtc->flags); + clear_bit_unlock(RTC_DEV_BUSY, &rtc->flags); return 0; } -- 2.7.4