trivial clean up to zlc_setup

trivial clean up to zlc_setup

[KOSAKI Motohiro]

Hi

I found very small bug during review mel's 2 zonelist patch series.

this patch is trivial clean up.
jiffies subtraction may cause overflow problem.
it shold be used time_after().

Thanks.


Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
CC: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
CC: Paul Jackson <pj@sgi.com>
---
 mm/page_alloc.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Index: b/mm/page_alloc.c
===================================================================
--- a/mm/page_alloc.c   2008-02-18 17:17:25.000000000 +0900
+++ b/mm/page_alloc.c   2008-02-29 15:17:03.000000000 +0900
@@ -1294,7 +1294,7 @@ static nodemask_t *zlc_setup(struct zone
        if (!zlc)
                return NULL;

-       if (jiffies - zlc->last_full_zap > 1 * HZ) {
+       if (time_after(jiffies, zlc->last_full_zap + HZ)) {
                bitmap_zero(zlc->fullzones, MAX_ZONES_PER_ZONELIST);
                zlc->last_full_zap = jiffies;
        }

Re: trivial clean up to zlc_setup

[Andrew Morton]

On Fri, 29 Feb 2008 15:19:39 +0900 KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> wrote:

> Hi
> 
> I found very small bug during review mel's 2 zonelist patch series.
> 
> this patch is trivial clean up.
> jiffies subtraction may cause overflow problem.
> it shold be used time_after().
> 
> Thanks.
> 
> 
> Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
> CC: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
> CC: Paul Jackson <pj@sgi.com>
> ---
>  mm/page_alloc.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> Index: b/mm/page_alloc.c
> ===================================================================
> --- a/mm/page_alloc.c   2008-02-18 17:17:25.000000000 +0900
> +++ b/mm/page_alloc.c   2008-02-29 15:17:03.000000000 +0900
> @@ -1294,7 +1294,7 @@ static nodemask_t *zlc_setup(struct zone
>         if (!zlc)
>                 return NULL;
> 
> -       if (jiffies - zlc->last_full_zap > 1 * HZ) {
> +       if (time_after(jiffies, zlc->last_full_zap + HZ)) {
>                 bitmap_zero(zlc->fullzones, MAX_ZONES_PER_ZONELIST);
>                 zlc->last_full_zap = jiffies;
>         }

That's a mainline bug.  Also present in 2.6.24, maybe earlier.

But it's a minor one - we'll fix it up one second later (yes?)

Re: trivial clean up to zlc_setup

[KOSAKI Motohiro]

> > -       if (jiffies - zlc->last_full_zap > 1 * HZ) {
> > +       if (time_after(jiffies, zlc->last_full_zap + HZ)) {
> >                 bitmap_zero(zlc->fullzones, MAX_ZONES_PER_ZONELIST);
> >                 zlc->last_full_zap = jiffies;
> >         }
> 
> That's a mainline bug.  Also present in 2.6.24, maybe earlier.
> But it's a minor one - we'll fix it up one second later (yes?)

I think so, may be.

Thanks.

-kosaki

Re: trivial clean up to zlc_setup

[S.Çağlar Onur]

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Hi;

29 Şub 2008 Cum tarihinde, KOSAKI Motohiro şunları yazmıştı: 
> > > -       if (jiffies - zlc->last_full_zap > 1 * HZ) {
> > > +       if (time_after(jiffies, zlc->last_full_zap + HZ)) {
> > >                 bitmap_zero(zlc->fullzones, MAX_ZONES_PER_ZONELIST);
> > >                 zlc->last_full_zap = jiffies;
> > >         }
> > 
> > That's a mainline bug.  Also present in 2.6.24, maybe earlier.
> > But it's a minor one - we'll fix it up one second later (yes?)
> 
> I think so, may be.

Andrew "Use time_* macros" series i sent to LKML on 14 Feb [1] has this chunk also (and by the way this version not includes linux/jiffies.h for time_after macro). Some part of this series already gone into Linus's tree with different subsystems but others not received any review/ack or nack. Will you grab others for -mm or will i resend them?

[1] http://lkml.org/lkml/2008/2/14/195

Cheers
-- 
S.Çağlar Onur <caglar@pardus.org.tr>
http://cekirdek.pardus.org.tr/~caglar/

Linux is like living in a teepee. No Windows, no Gates and an Apache in house!

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Re: trivial clean up to zlc_setup

[Paul Jackson]

kosaki-san wrote:
> -       if (jiffies - zlc->last_full_zap > 1 * HZ) {
> +       if (time_after(jiffies, zlc->last_full_zap + HZ)) {

Nice catch.  Thank-you.

-- 
                  I won't rest till it's the best ...
                  Programmer, Linux Scalability
                  Paul Jackson <pj@sgi.com> 1.940.382.4214