[PATCH 1/4][RFC v2] PM / sleep: Avoid accessing frozen_cpus if it is NULL

[Chen Yu]

frozen_cpus might be NULL if the allocation in previous
alloc_frozen_cpus failed, when CONFIG_CPUMASK_OFFSTACK
is set.

This patch avoid accessing this cpumask if it is NULL.

Signed-off-by: Chen Yu <yu.c.chen@xxxxxxxxx>
---
 kernel/cpu.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/kernel/cpu.c b/kernel/cpu.c
index d948e44..d25266e 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -1021,6 +1021,8 @@ int disable_nonboot_cpus(void)
 {
 	int cpu, first_cpu, error = 0;
 
+	if (frozen_cpus == NULL)
+		return -ENOMEM;
 	cpu_maps_update_begin();
 	first_cpu = cpumask_first(cpu_online_mask);
 	/*
@@ -1072,6 +1074,8 @@ void enable_nonboot_cpus(void)
 {
 	int cpu, error;
 
+	if (frozen_cpus == NULL)
+		return;
 	/* Allow everyone to use the CPU hotplug again */
 	cpu_maps_update_begin();
 	WARN_ON(--cpu_hotplug_disabled < 0);
-- 
2.7.4