On Thu, 1 Nov 2012, Chuansheng Liu wrote:
>
> Some posix clock interface directly use the variable rtcdev,
> cleanup it here by alarmtimer_get_rtcdev().
>
> Signed-off-by: liu chuansheng <chuansheng....@intel.com>
> ---
> kernel/time/alarmtimer.c | 13 ++++++-------
> 1 files changed, 6 insertions(+), 7 deletions(-)
>
> diff --git a/kernel/time/alarmtimer.c b/kernel/time/alarmtimer.c
> index 4fc17cb..5490fa8 100644
> --- a/kernel/time/alarmtimer.c
> +++ b/kernel/time/alarmtimer.c
> @@ -86,11 +86,10 @@ static int alarmtimer_rtc_add_device(struct device *dev,
> return -1;
>
> mutex_lock(&rtcdev_mutex);
> - if (!rtcdev) {
> - rtcdev = rtc;
> - /* hold a reference so it doesn't go away */
> - get_device(dev);
> - }
> + rtcdev = rtc;
> + /* hold a reference so it doesn't go away */
> + get_device(dev);
> +
Brilliant.
rtcdev = NULL
CPU0 CPU 1
alarmtimer_rtc_add_device(A)
if (rtcdev) alarmtimer_rtc_add_device(B)
return -EBUSY; if (rtcdev)
mutex_lock(); return -EBUSY;
rtcdev = A; mutex_lock();
mutex_unlock;
bla = alarmtimer_rtc_get_device()
So bla = A
mutex_lock() returns
rtcdev = B;
mutex_unlock();
The next call to alarmtimer_rtc_get_device() will return B. Not what
you want. Maybe you want that, but then your patch is missing an
explanation why you want that and why this would be a desired
behaviour.
Thanks,
tglx
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