Re: [PATCH] alarmtimer: add .remove_dev hook to put device

[John Stultz]

On 07/10/2012 08:46 PM, Shawn Guo wrote:
> Hi John,
>
> Is this patch a valid fix or just a noise?

Sorry! This is on my list, but I've not had a chance to get to it.

I'll try to get a closer look later this week!

Thanks for reminding me, and sorry again!
-john


> 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@xxxxxxxxxx>
> > ---
> >   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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