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| author | Jiri Kosina <jkosina@suse.cz> | 2007-12-04 23:45:05 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@woody.linux-foundation.org> | 2007-12-05 09:21:18 -0800 |
| commit | 372a302e9a892229206aafca0352584a745bc5f3 (patch) | |
| tree | 14cf4e06735d8dd9284e843f36a5abcfcc4cc476 /drivers | |
| parent | 5cd17569fd0eeca510735e63a6061291e3971bf6 (diff) | |
| download | lwn-372a302e9a892229206aafca0352584a745bc5f3.tar.gz lwn-372a302e9a892229206aafca0352584a745bc5f3.zip | |
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 <jkosina@suse.cz>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: David Brownell <david-b@pacbell.net>
Acked-by: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/rtc/interface.c | 4 | ||||
| -rw-r--r-- | 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 a4f56e95cf96..f1e00ff54ce8 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 ae1bf177d625..025c60a17a4a 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; } |