4.4-stable review patch. If anyone has any objections, please let me know.
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[ Upstream 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@gmai... Signed-off-by: Thomas Gleixner tglx@linutronix.de Signed-off-by: Sasha Levin sashal@kernel.org --- kernel/cpu.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-)
diff --git a/kernel/cpu.c b/kernel/cpu.c index 40d20bf5de28..42ce0b0ae5c5 100644 --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -183,10 +183,17 @@ 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); @@ -626,7 +633,7 @@ 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;