4.4-stable review patch. If anyone has any objections, please let me know. ------------------ [ 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@xxxxxxxxx> Cc: peterz@xxxxxxxxxxxxx Cc: linux-pm@xxxxxxxxxxxxxxx Cc: oleg@xxxxxxxxxx Link: http://lkml.kernel.org/r/1465541008-12476-1-git-send-email-lianwei.wang@xxxxxxxxx Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- 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; -- 2.19.1
