lkml.org 
[lkml]   [2020]   [Jul]   [17]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Date
SubjectRe: [External] Re: [PATCH RESEND] smp: Fix a potential usage of stale nr_cpus
On Sat, Jul 18, 2020 at 4:15 AM Thomas Gleixner <tglx@linutronix.de> wrote:
>
> Muchun,
>
> Muchun Song <songmuchun@bytedance.com> writes:
>
> > The get_option() maybe return 0, it means that the nr_cpus is
> > not initialized.
>
> Good catch, but see below.
>
> > Then we will use the stale nr_cpus to initialize
>
> We use nothing. Please describe your changes in technical neutral
> language.
>
> > the nr_cpu_ids. So fix it.
>
> 'So fix it.' is not much valuable information. What about:
>
> Check the return value to prevent this.
>
> Hmm?

Looks fine to me. Thanks.

>
> > Signed-off-by: Muchun Song <songmuchun@bytedance.com>
> > ---
> > kernel/smp.c | 3 +--
> > 1 file changed, 1 insertion(+), 2 deletions(-)
> >
> > diff --git a/kernel/smp.c b/kernel/smp.c
> > index 472c2b274c65..2a9a04acf123 100644
> > --- a/kernel/smp.c
> > +++ b/kernel/smp.c
> > @@ -634,8 +634,7 @@ static int __init nrcpus(char *str)
> > {
> > int nr_cpus;
> >
> > - get_option(&str, &nr_cpus);
> > - if (nr_cpus > 0 && nr_cpus < nr_cpu_ids)
> > + if (get_option(&str, &nr_cpus) && nr_cpus > 0 && nr_cpus < nr_cpu_ids)
> > nr_cpu_ids = nr_cpus;
> >
> > return 0;
>
> get_option() can return 0 - 3:
>
> * 0 - no int in string
> * 1 - int found, no subsequent comma
> * 2 - int found including a subsequent comma
> * 3 - hyphen found to denote a range
>
> For this parameter exists only one valid format: '1 - int found, no comma',
> right?

Yeah.

>
> So why fixing it just half and why returning '0' aka success if the
> parameter is bogus?

Thanks. Will fix it.

>
> Thanks,
>
> tglx



--
Yours,
Muchun

\
 
 \ /
  Last update: 2020-07-18 04:31    [W:0.048 / U:0.620 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site