linux-kernel - Re: x86, vmi: TSC going backwards check in vmi clocksource

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Date:	Fri, 20 Feb 2009 10:23:18 -0800
From:	Alok Kataria <akataria@...are.com>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	the arch/x86 maintainers <x86@...nel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Zach Amsden <zach@...are.com>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: x86, vmi: TSC going backwards check in vmi clocksource

On Fri, 2009-02-20 at 09:58 -0800, Ingo Molnar wrote:
> * Alok Kataria <akataria@...are.com> wrote:
> 
> >  static cycle_t read_real_cycles(void)
> >  {
> > -	return vmi_timer_ops.get_cycle_counter(VMI_CYCLES_REAL);
> > +	cycle_t ret = (cycle_t)vmi_timer_ops.get_cycle_counter(VMI_CYCLES_REAL);
> > +	return ret >= clocksource_vmi.cycle_last ?
> > +		ret : clocksource_vmi.cycle_last;
> 
> btw., could you please clean this up to use max()?

Please find it below, on top of current tip/master.

--

cleanup vmi_read_cycles to use max()

Signed-off-by: Alok N Kataria <akataria@...are.com>

---

 arch/x86/kernel/vmiclock_32.c |    3 +--
 1 files changed, 1 insertions(+), 2 deletions(-)


diff --git a/arch/x86/kernel/vmiclock_32.c b/arch/x86/kernel/vmiclock_32.c
index 9cd28c0..b77ad57 100644
--- a/arch/x86/kernel/vmiclock_32.c
+++ b/arch/x86/kernel/vmiclock_32.c
@@ -288,8 +288,7 @@ static struct clocksource clocksource_vmi;
 static cycle_t read_real_cycles(void)
 {
 	cycle_t ret = (cycle_t)vmi_timer_ops.get_cycle_counter(VMI_CYCLES_REAL);
-	return ret >= clocksource_vmi.cycle_last ?
-		ret : clocksource_vmi.cycle_last;
+	return max(ret, clocksource_vmi.cycle_last);
 }
 
 static struct clocksource clocksource_vmi = {


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