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From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: Fri, 4 Aug 2017 18:31:00 +0200
Subject: [PATCH 229/354] hotplug: duct-tape RT-rwlock usage for non-RT
Origin: https://git.kernel.org/cgit/linux/kernel/git/rt/linux-stable-rt.git/commit?id=821ee7012851443150f058ee24efe13f6bb4e00d
This type is only available on -RT. We need to craft something for
non-RT. Since the only migrate_disable() user is -RT only, there is no
damage.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
kernel/cpu.c | 14 +++++++++++++-
1 file changed, 13 insertions(+), 1 deletion(-)
diff --git a/kernel/cpu.c b/kernel/cpu.c
index 97d5f24fa435..605276e96143 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -78,7 +78,7 @@ static DEFINE_PER_CPU(struct cpuhp_cpu_state, cpuhp_state) = {
.fail = CPUHP_INVALID,
};
-#ifdef CONFIG_HOTPLUG_CPU
+#if defined(CONFIG_HOTPLUG_CPU) && defined(CONFIG_PREEMPT_RT_FULL)
static DEFINE_PER_CPU(struct rt_rw_lock, cpuhp_pin_lock) = \
__RWLOCK_RT_INITIALIZER(cpuhp_pin_lock);
#endif
@@ -294,6 +294,7 @@ static int cpu_hotplug_disabled;
*/
void pin_current_cpu(void)
{
+#ifdef CONFIG_PREEMPT_RT_FULL
struct rt_rw_lock *cpuhp_pin;
unsigned int cpu;
int ret;
@@ -316,6 +317,7 @@ void pin_current_cpu(void)
goto again;
}
current->pinned_on_cpu = cpu;
+#endif
}
/**
@@ -323,6 +325,7 @@ void pin_current_cpu(void)
*/
void unpin_current_cpu(void)
{
+#ifdef CONFIG_PREEMPT_RT_FULL
struct rt_rw_lock *cpuhp_pin = this_cpu_ptr(&cpuhp_pin_lock);
if (WARN_ON(current->pinned_on_cpu != smp_processor_id()))
@@ -330,6 +333,7 @@ void unpin_current_cpu(void)
current->pinned_on_cpu = -1;
__read_rt_unlock(cpuhp_pin);
+#endif
}
DEFINE_STATIC_PERCPU_RWSEM(cpu_hotplug_lock);
@@ -954,7 +958,9 @@ static int take_cpu_down(void *_param)
static int takedown_cpu(unsigned int cpu)
{
+#ifdef CONFIG_PREEMPT_RT_FULL
struct rt_rw_lock *cpuhp_pin = per_cpu_ptr(&cpuhp_pin_lock, cpu);
+#endif
struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
int err;
@@ -967,14 +973,18 @@ static int takedown_cpu(unsigned int cpu)
*/
irq_lock_sparse();
+#ifdef CONFIG_PREEMPT_RT_FULL
__write_rt_lock(cpuhp_pin);
+#endif
/*
* So now all preempt/rcu users must observe !cpu_active().
*/
err = stop_machine_cpuslocked(take_cpu_down, NULL, cpumask_of(cpu));
if (err) {
+#ifdef CONFIG_PREEMPT_RT_FULL
__write_rt_unlock(cpuhp_pin);
+#endif
/* CPU refused to die */
irq_unlock_sparse();
/* Unpark the hotplug thread so we can rollback there */
@@ -993,7 +1003,9 @@ static int takedown_cpu(unsigned int cpu)
wait_for_ap_thread(st, false);
BUG_ON(st->state != CPUHP_AP_IDLE_DEAD);
+#ifdef CONFIG_PREEMPT_RT_FULL
__write_rt_unlock(cpuhp_pin);
+#endif
/* Interrupts are moved away from the dying cpu, reenable alloc/free */
irq_unlock_sparse();
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