[PATCH 4.18 17/79] cpu/hotplug: Make bringup/teardown of smp threads symmetric

From: Greg Kroah-Hartman
Date: Tue Aug 14 2018 - 13:24:35 EST


4.18-stable review patch. If anyone has any objections, please let me know.

------------------

From: Thomas Gleixner <tglx@xxxxxxxxxxxxx>

The asymmetry caused a warning to trigger if the bootup was stopped in state
CPUHP_AP_ONLINE_IDLE. The warning no longer triggers as kthread_park() can
now be invoked on already or still parked threads. But there is still no
reason to have this be asymmetric.

Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Acked-by: Ingo Molnar <mingo@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
kernel/cpu.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)

--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -754,7 +754,6 @@ static int takedown_cpu(unsigned int cpu

/* Park the smpboot threads */
kthread_park(per_cpu_ptr(&cpuhp_state, cpu)->thread);
- smpboot_park_threads(cpu);

/*
* Prevent irq alloc/free while the dying cpu reorganizes the
@@ -1332,7 +1331,7 @@ static struct cpuhp_step cpuhp_hp_states
[CPUHP_AP_SMPBOOT_THREADS] = {
.name = "smpboot/threads:online",
.startup.single = smpboot_unpark_threads,
- .teardown.single = NULL,
+ .teardown.single = smpboot_park_threads,
},
[CPUHP_AP_IRQ_AFFINITY_ONLINE] = {
.name = "irq/affinity:online",