linux-kernel - [tip: sched/core] smp: Fix a potential usage of stale nr

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Message-ID: <159540914653.4006.6322052574571138388.tip-bot2@tip-bot2>
Date:   Wed, 22 Jul 2020 09:12:26 -0000
From:   "tip-bot2 for Muchun Song" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     Muchun Song <songmuchun@...edance.com>,
        "Peter Zijlstra (Intel)" <peterz@...radead.org>,
        x86 <x86@...nel.org>, LKML <linux-kernel@...r.kernel.org>
Subject: [tip: sched/core] smp: Fix a potential usage of stale nr_cpus

The following commit has been merged into the sched/core branch of tip:

Commit-ID:     589343569d7b58a64ec2446e6686c8e79aea7fcf
Gitweb:        https://git.kernel.org/tip/589343569d7b58a64ec2446e6686c8e79aea7fcf
Author:        Muchun Song <songmuchun@...edance.com>
AuthorDate:    Thu, 16 Jul 2020 15:04:57 +08:00
Committer:     Peter Zijlstra <peterz@...radead.org>
CommitterDate: Wed, 22 Jul 2020 10:22:04 +02:00

smp: Fix a potential usage of stale nr_cpus

The get_option() maybe return 0, it means that the nr_cpus is
not initialized. Then we will use the stale nr_cpus to initialize
the nr_cpu_ids. So fix it.

Signed-off-by: Muchun Song <songmuchun@...edance.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Link: https://lkml.kernel.org/r/20200716070457.53255-1-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 aa17eed..d0ae8eb 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;