linux-kernel - Re: [PATCH] posix-timers: CLOCK_MONOTONIC_RAW: fix the usage of ->it

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Message-ID: <alpine.LFD.2.00.0812202134330.3376@localhost.localdomain>
Date:	Sat, 20 Dec 2008 21:37:32 +0100 (CET)
From:	Thomas Gleixner <tglx@...utronix.de>
To:	Oleg Nesterov <oleg@...hat.com>
cc:	Eric Sesterhenn <snakebyte@....de>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] posix-timers: CLOCK_MONOTONIC_RAW: fix the usage of
 ->it_clock

On Sat, 20 Dec 2008, Oleg Nesterov wrote:
> On 12/20, Thomas Gleixner wrote:
> >
> > On Sat, 20 Dec 2008, Oleg Nesterov wrote:
> >
> > > -static int common_timer_create(struct k_itimer *new_timer)
> > > +static inline int
> > > +__common_timer_init(struct k_itimer *timer, enum hrtimer_mode mode)
> > >  {
> > > -	hrtimer_init(&new_timer->it.real.timer, new_timer->it_clock, 0);
> > > +	clockid_t clock_id = timer->it_clock ?
> > > +				CLOCK_MONOTONIC : CLOCK_REALTIME;
> > > +	hrtimer_init(&timer->it.real.timer, clock_id, mode);
> > >  	return 0;
> > >  }
> >
> > No, this is wrong. We do not want to create a timer for
> > CLOCK_MONOTONIC_RAW.
> 
> OK, thanks.
> 
> I thought that the intent was to allow the creation.

No. 

1. CLOCK_MONOTONIC_RAW and CLOCK_MONOTONIC are diffferent beasts

2. CLOCK_MONOTONIC_RAW was created to allow user space to read out the
non NTP frequency corrected raw system time. That's mainly for the NTP
folks so they have a better idea what's the hardware's idea of time
is.
 
> Then we should we shoould add clock_monotonic_raw->timer_create()
> which returns -EINVAL ?

That's what I just sent out :) I looked into this offline and had the
fix ready to send out when I noticed yours.

Thanks,

	tglx
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