Re: [PATCH] sched: fix the wrong mask_len

From: Peter Zijlstra
Date: Fri Oct 17 2008 - 06:58:21 EST


On Fri, 2008-10-17 at 12:33 +0200, Peter Zijlstra wrote:
> On Fri, 2008-10-17 at 19:25 +0900, KOSAKI Motohiro wrote:
> > > If the NR_CPUS isn't a multiple of 32, we get a truncated string of sched
> > > domains by catting /proc/schedstat. This is caused by the wrong mask_len.
> > >
> > > This patch fix it.
> > >
> > > Signed-off-by: Miao Xie <miaox@xxxxxxxxxxxxxx>
> > >
> > > ---
> > > kernel/sched_stats.h | 2 +-
> > > 1 files changed, 1 insertions(+), 1 deletions(-)
> > >
> > > diff --git a/kernel/sched_stats.h b/kernel/sched_stats.h
> > > index 8385d43..81365b3 100644
> > > --- a/kernel/sched_stats.h
> > > +++ b/kernel/sched_stats.h
> > > @@ -9,7 +9,7 @@
> > > static int show_schedstat(struct seq_file *seq, void *v)
> > > {
> > > int cpu;
> > > - int mask_len = NR_CPUS/32 * 9;
> > > + int mask_len = (NR_CPUS/32 + 1) * 9;
> > > char *mask_str = kmalloc(mask_len, GFP_KERNEL);
> > >
> >
> > DIV_ROUND_UP() is better?
>
> Agreed


---
Subject: sched: fix the wrong mask_len
From: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Date: Fri Oct 17 12:55:57 CEST 2008

If the NR_CPUS isn't a multiple of 32, we get a truncated string of sched
domains by catting /proc/schedstat. This is caused by the wrong mask_len.

Reported-by: Miao Xie <miaox@xxxxxxxxxxxxxx>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
---
kernel/sched_stats.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

Index: linux-2.6/kernel/sched_stats.h
===================================================================
--- linux-2.6.orig/kernel/sched_stats.h
+++ linux-2.6/kernel/sched_stats.h
@@ -9,7 +9,7 @@
static int show_schedstat(struct seq_file *seq, void *v)
{
int cpu;
- int mask_len = NR_CPUS/32 * 9;
+ int mask_len = DIV_ROUND_UP(NR_CPUS, 32) * 9;
char *mask_str = kmalloc(mask_len, GFP_KERNEL);

if (mask_str == NULL)


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