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SubjectRe: [PATCH] alarmtimer: add .remove_dev hook to put device
Hi John,

Is this patch a valid fix or just a noise?

Regards,
Shawn

On Thu, Jul 05, 2012 at 12:13:07AM +0800, Shawn Guo wrote:
> The following is a test sequence that installs a rtc module, remove it
> and installs it again.
>
> $ insmod rtc-snvs.ko
> snvs_rtc 20cc034.snvs-rtc-lp: rtc core: registered 20cc034.snvs-rtc-lp as rtc0
> $ hwclock
> Thu Jul 5 08:53:35 2012 0.000000 seconds
> $ rmmod rtc-snvs.ko
> $ insmod rtc-snvs.ko
> snvs_rtc 20cc034.snvs-rtc-lp: rtc core: registered 20cc034.snvs-rtc-lp as rtc1
> $ hwclock
> hwclock: can't open '/dev/misc/rtc': No such file or directory
> $
>
> The device is registered as rtc0 for the first time insmod, while it
> becomes rtc1 with the later insmod.
>
> It's root caused by alarmtimer which never puts the device even when
> the rtc is removed. The patch adds a .remove_dev hook to have device
> properly put, so that above insmod/rmmod sequence can the rtc device
> registered in a consistent behavior.
>
> Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
> ---
> kernel/time/alarmtimer.c | 12 ++++++++++++
> 1 files changed, 12 insertions(+), 0 deletions(-)
>
> diff --git a/kernel/time/alarmtimer.c b/kernel/time/alarmtimer.c
> index aa27d39..39e8773 100644
> --- a/kernel/time/alarmtimer.c
> +++ b/kernel/time/alarmtimer.c
> @@ -96,6 +96,17 @@ static int alarmtimer_rtc_add_device(struct device *dev,
> return 0;
> }
>
> +static void alarmtimer_rtc_remove_device(struct device *dev,
> + struct class_interface *class_intf)
> +{
> + unsigned long flags;
> +
> + spin_lock_irqsave(&rtcdev_lock, flags);
> + rtcdev = NULL;
> + put_device(dev);
> + spin_unlock_irqrestore(&rtcdev_lock, flags);
> +}
> +
> static inline void alarmtimer_rtc_timer_init(void)
> {
> rtc_timer_init(&rtctimer, NULL, NULL);
> @@ -103,6 +114,7 @@ static inline void alarmtimer_rtc_timer_init(void)
>
> static struct class_interface alarmtimer_rtc_interface = {
> .add_dev = &alarmtimer_rtc_add_device,
> + .remove_dev = &alarmtimer_rtc_remove_device,
> };
>
> static int alarmtimer_rtc_interface_setup(void)
> --
> 1.7.5.4
>
>



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