Commit a3c8dc25 authored Jun 09, 2016 by Lianwei Wang

UPSTREAM: cpu/hotplug: Handle unbalanced hotplug enable/disable



(cherry picked from commit 01b41159066531cc8d664362ff0cd89dd137bbfa)

When cpu_hotplug_enable() is called unbalanced w/o a preceeding
cpu_hotplug_disable() the code emits a warning, but happily decrements the
disabled counter. This causes the next operations to malfunction.

Prevent the decrement and just emit a warning.

Signed-off-by: Lianwei Wang <lianwei.wang@gmail.com>
Cc: peterz@infradead.org
Cc: linux-pm@vger.kernel.org
Cc: oleg@redhat.com
Link: http://lkml.kernel.org/r/1465541008-12476-1-git-send-email-lianwei.wang@gmail.com


Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

parent 4a8b645c

kernel/cpu.c

+9 −2

Original line number	Diff line number	Diff line
		@@ -185,10 +185,17 @@ void cpu_hotplug_disable(void)
		}
		EXPORT_SYMBOL_GPL(cpu_hotplug_disable);

		static void __cpu_hotplug_enable(void)
		{
		if (WARN_ONCE(!cpu_hotplug_disabled, "Unbalanced cpu hotplug enable\n"))
		return;
		cpu_hotplug_disabled--;
		}

		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);
		@@ -631,7 +638,7 @@ 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;