From: Thomas Gleixner <tglx@linutronix.de>
To: Muchun Song <songmuchun@bytedance.com>,
peterz@infradead.org, mingo@kernel.org, bigeasy@linutronix.de,
namit@vmware.com
Cc: linux-kernel@vger.kernel.org, Muchun Song <songmuchun@bytedance.com>
Subject: Re: [PATCH RESEND] smp: Fix a potential usage of stale nr_cpus
Date: Fri, 17 Jul 2020 22:15:34 +0200 [thread overview]
Message-ID: <87k0z1rj89.fsf@nanos.tec.linutronix.de> (raw)
In-Reply-To: <20200716070457.53255-1-songmuchun@bytedance.com>
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?
> 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?
So why fixing it just half and why returning '0' aka success if the
parameter is bogus?
Thanks,
tglx
next prev parent reply other threads:[~2020-07-17 20:15 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-16 7:04 [PATCH RESEND] smp: Fix a potential usage of stale nr_cpus Muchun Song
2020-07-17 20:15 ` Thomas Gleixner [this message]
2020-07-18 2:29 ` [External] " Muchun Song
2020-07-22 9:12 ` [tip: sched/core] " tip-bot2 for Muchun Song
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