cpu-hotplug: convert cpu_hotplug_disabled to a counter

[cascardo/linux.git] / kernel / cpu.c

diff --git a/kernel/cpu.c b/kernel/cpu.c
index 5644ec5..0fca2ba 100644 (file)
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -191,14 +191,14 @@ void cpu_hotplug_done(void)
 void cpu_hotplug_disable(void)
 {
        cpu_maps_update_begin();
-       cpu_hotplug_disabled = 1;
+       cpu_hotplug_disabled++;
        cpu_maps_update_done();
 }
 
 void cpu_hotplug_enable(void)
 {
        cpu_maps_update_begin();
-       cpu_hotplug_disabled = 0;
+       WARN_ON(--cpu_hotplug_disabled < 0);
        cpu_maps_update_done();
 }
 
@@ -608,13 +608,18 @@ int disable_nonboot_cpus(void)
                }
        }
 
-       if (!error) {
+       if (!error)
                BUG_ON(num_online_cpus() > 1);
-               /* Make sure the CPUs won't be enabled by someone else */
-               cpu_hotplug_disabled = 1;
-       } else {
+       else
                pr_err("Non-boot CPUs are not disabled\n");
-       }
+
+       /*
+        * Make sure the CPUs won't be enabled by someone else. We need to do
+        * this even in case of failure as all disable_nonboot_cpus() users are
+        * supposed to do enable_nonboot_cpus() on the failure path.
+        */
+       cpu_hotplug_disabled++;
+
        cpu_maps_update_done();
        return error;
 }
@@ -633,7 +638,7 @@ void __ref enable_nonboot_cpus(void)
 
        /* Allow everyone to use the CPU hotplug again */
        cpu_maps_update_begin();
-       cpu_hotplug_disabled = 0;
+       WARN_ON(--cpu_hotplug_disabled < 0);
        if (cpumask_empty(frozen_cpus))
                goto out;