From: Arnd Bergmann <arnd@arndb.de>
To: Baolin Wang <baolin.wang@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>, linux-kernel@vger.kernel.org,
        y2038 Mailman List <y2038@lists.linaro.org>
Subject: Re: [PATCH v3 05/22] posix-timers:Convert to the 64bit methods for the timer_gettime syscall function
Date: Tue, 12 May 2015 09:33:18 +0200
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On Tuesday 12 May 2015 10:05:45 Baolin Wang wrote:
> On 12 May 2015 at 00:30, Arnd Bergmann <arnd@arndb.de> wrote:
> 
> > On Monday 11 May 2015 19:15:14 Baolin Wang wrote:
> > > +static int default_timer_get64(struct k_itimer *timr,
> > > +                              struct itimerspec64 *cur_setting64)
> > > +{
> > > +       struct itimerspec cur_setting;
> > > +       struct k_clock *kc = clockid_to_kclock(timr->it_clock);
> > > +
> > > +       kc->timer_get(timr, &cur_setting);
> > > +       return 0;
> > > +}
> >
> > This function is unfortunately incorrect, because you never copy
> > the cur_setting value into cur_setting64.
> >
> 
> Thanks for your comments. But i think this is just  a temporary default
> function,
> and will be removed after all the drivers' conversion, so just ensure it
> won't
> cause the kernel crash.
> 

No, that function has to do the right thing. The purpose of the function
is to keep the kernel working when only half the series is applied, this
is a fundamental part of how we do kernel development: Each patch in
you series needs to bring the kernel closer to what we want to have in
the end but not introduce bugs. Your current function stops the
timer_gettime() system call from working and makes it return uninitialized
kernel data.

	Arnd
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