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cpu/hotplug: handle unbalanced hotplug enable/disable #291

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cpu/hotplug: handle unbalanced hotplug enable/disable #291

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21 changes: 17 additions & 4 deletions kernel/cpu.c
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Original file line number Diff line number Diff line change
Expand Up @@ -245,6 +245,19 @@ void cpu_hotplug_done(void)
cpuhp_lock_release();
}

static void _cpu_hotplug_disable(void)
{
cpu_hotplug_disabled++;
}

static void _cpu_hotplug_enable(void)
{
if (WARN(!cpu_hotplug_disabled, "Unbalanced cpu hotplug enable\n"))
return;

cpu_hotplug_disabled--;
}

/*
* Wait for currently running CPU hotplug operations to complete (if any) and
* disable future CPU hotplug (from sysfs). The 'cpu_add_remove_lock' protects
Expand All @@ -255,15 +268,15 @@ void cpu_hotplug_done(void)
void cpu_hotplug_disable(void)
{
cpu_maps_update_begin();
cpu_hotplug_disabled++;
_cpu_hotplug_disable();
cpu_maps_update_done();
}
EXPORT_SYMBOL_GPL(cpu_hotplug_disable);

void cpu_hotplug_enable(void)
{
cpu_maps_update_begin();
WARN_ON(--cpu_hotplug_disabled < 0);
_cpu_hotplug_enable();
cpu_maps_update_done();
}
EXPORT_SYMBOL_GPL(cpu_hotplug_enable);
Expand Down Expand Up @@ -1054,7 +1067,7 @@ int disable_nonboot_cpus(void)
* 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_hotplug_disable();

cpu_maps_update_done();
return error;
Expand All @@ -1074,7 +1087,7 @@ void enable_nonboot_cpus(void)

/* Allow everyone to use the CPU hotplug again */
cpu_maps_update_begin();
WARN_ON(--cpu_hotplug_disabled < 0);
_cpu_hotplug_enable();
if (cpumask_empty(frozen_cpus))
goto out;

Expand Down