From: Muchun Song <songmuchun@bytedance.com>
Date: Thu, 16 Jul 2020 07:04:57 +0000 (+0800)
Subject: smp: Fix a potential usage of stale nr_cpus
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=589343569d7b58a64ec2446e6686c8e79aea7fcf;p=linux.git

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@bytedance.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200716070457.53255-1-songmuchun@bytedance.com
---

diff --git a/kernel/smp.c b/kernel/smp.c
index aa17eedff5bee..d0ae8eb6bf8b4 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;