lkml.org 
[lkml]   [2011]   [Jul]   [29]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH] vmscan: Remove if statement that will never trigger
On Fri, 29 Jul 2011, KOSAKI Motohiro wrote:

> (2011/07/29 6:05), Jesper Juhl wrote:
> > We have this code in mm/vmscan.c:shrink_slab() :
> > ...
> > if (total_scan < 0) {
> > printk(KERN_ERR "shrink_slab: %pF negative objects to "
> > "delete nr=%ld\n",
> > shrinker->shrink, total_scan);
> > total_scan = max_pass;
> > }
> > ...
> > but since 'total_scan' is of type 'unsigned long' it will never be
> > less than zero, so there is no way we'll ever enter the true branch of
> > this if statement - so let's just remove it.
> >
> > Signed-off-by: Jesper Juhl <jj@chaosbits.net>
> > ---
> > mm/vmscan.c | 6 ------
> > 1 files changed, 0 insertions(+), 6 deletions(-)
> >
> > Compile tested only.
> >
> > diff --git a/mm/vmscan.c b/mm/vmscan.c
> > index 7ef6912..c07d9b1 100644
> > --- a/mm/vmscan.c
> > +++ b/mm/vmscan.c
> > @@ -271,12 +271,6 @@ unsigned long shrink_slab(struct shrink_control *shrink,
> > delta *= max_pass;
> > do_div(delta, lru_pages + 1);
> > total_scan += delta;
> > - if (total_scan < 0) {
> > - printk(KERN_ERR "shrink_slab: %pF negative objects to "
> > - "delete nr=%ld\n",
> > - shrinker->shrink, total_scan);
> > - total_scan = max_pass;
> > - }
> >
> > /*
> > * We need to avoid excessive windup on filesystem shrinkers
>
> Good catch.
>
> However this seems intended to catch a overflow. So, I'd suggest to make proper
> overflow check instead.
>
Right. We probably shouldn't just remove it.

I'll cook a new version of the patch tonight that properly checks for
overflow.


--
Jesper Juhl <jj@chaosbits.net> http://www.chaosbits.net/
Don't top-post http://www.catb.org/jargon/html/T/top-post.html
Plain text mails only, please.



\
 
 \ /
  Last update: 2011-07-29 11:19    [from the cache]
©2003-2014 Jasper Spaans. Advertise on this site