Subject: Re: [PATCH] Fix next_timer_interrupt() for hrtimer
From: john stultz <johnstul@us.ibm.com>
To: Tony Lindgren <tony@atomide.com>
Cc: linux-kernel@vger.kernel.org, Thomas Gleixner <tglx@linutronix.de>,
       Martin Schwidefsky <schwidefsky@de.ibm.com>,
       Russell King <linux@arm.linux.org.uk>, Con Kolivas <kernel@kolivas.org>
In-Reply-To: <20060224004049.GD4578@atomide.com>
References: <20060224002653.GC4578@atomide.com>
	 <1140741472.1271.64.camel@cog.beaverton.ibm.com>
	 <20060224004049.GD4578@atomide.com>
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Date: Thu, 23 Feb 2006 16:50:07 -0800
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On Thu, 2006-02-23 at 16:40 -0800, Tony Lindgren wrote:
> * john stultz <johnstul@us.ibm.com> [060223 16:37]:
> > On Thu, 2006-02-23 at 16:26 -0800, Tony Lindgren wrote:
> > > +	tv = ktime_to_timespec(event);
> > > +
> > > +	/* Assume read xtime_lock is held, so we can't use getnstimeofday() */
> > > +	sec = xtime.tv_sec;
> > > +	nsec = xtime.tv_nsec;
> > > +	while (unlikely(nsec >= NSEC_PER_SEC)) {
> > > +		nsec -= NSEC_PER_SEC;
> > > +		++sec;
> > > +	}
> > > +	tv.tv_sec = sec;
> > > +	tv.tv_nsec = nsec;
> > 
> > Er, I think you should be able to nest readers. Thus getnstimeofday()
> > should be safe to call. Or is the comment wrong and you are assuming a
> > write lock is held?
> 
> Oops, it's a write lock as next_timer_interrupt gets called from
> arch/*/time.c.

Also the above code just overwrites tv. 

Do you intend instead to add xtime to tv? 

thanks
-john


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