97 lines
2.6 KiB
Diff
97 lines
2.6 KiB
Diff
From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
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Date: Fri, 4 Aug 2017 18:31:00 +0200
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Subject: [PATCH] hotplug: duct-tape RT-rwlock usage for non-RT
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Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.18/older/patches-4.18.5-rt3.tar.xz
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This type is only available on -RT. We need to craft something for
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non-RT. Since the only migrate_disable() user is -RT only, there is no
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damage.
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Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
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---
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kernel/cpu.c | 14 +++++++++++++-
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1 file changed, 13 insertions(+), 1 deletion(-)
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--- a/kernel/cpu.c
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+++ b/kernel/cpu.c
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@@ -74,7 +74,7 @@ static DEFINE_PER_CPU(struct cpuhp_cpu_s
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.fail = CPUHP_INVALID,
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};
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-#ifdef CONFIG_HOTPLUG_CPU
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+#if defined(CONFIG_HOTPLUG_CPU) && defined(CONFIG_PREEMPT_RT_FULL)
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static DEFINE_PER_CPU(struct rt_rw_lock, cpuhp_pin_lock) = \
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__RWLOCK_RT_INITIALIZER(cpuhp_pin_lock);
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#endif
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@@ -293,6 +293,7 @@ static int cpu_hotplug_disabled;
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*/
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void pin_current_cpu(void)
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{
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+#ifdef CONFIG_PREEMPT_RT_FULL
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struct rt_rw_lock *cpuhp_pin;
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unsigned int cpu;
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int ret;
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@@ -317,6 +318,7 @@ void pin_current_cpu(void)
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goto again;
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}
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current->pinned_on_cpu = cpu;
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+#endif
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}
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/**
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@@ -324,6 +326,7 @@ void pin_current_cpu(void)
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*/
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void unpin_current_cpu(void)
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{
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+#ifdef CONFIG_PREEMPT_RT_FULL
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struct rt_rw_lock *cpuhp_pin = this_cpu_ptr(&cpuhp_pin_lock);
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if (WARN_ON(current->pinned_on_cpu != smp_processor_id()))
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@@ -331,6 +334,7 @@ void unpin_current_cpu(void)
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current->pinned_on_cpu = -1;
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__read_rt_unlock(cpuhp_pin);
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+#endif
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}
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DEFINE_STATIC_PERCPU_RWSEM(cpu_hotplug_lock);
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@@ -889,7 +893,9 @@ static int take_cpu_down(void *_param)
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static int takedown_cpu(unsigned int cpu)
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{
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+#ifdef CONFIG_PREEMPT_RT_FULL
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struct rt_rw_lock *cpuhp_pin = per_cpu_ptr(&cpuhp_pin_lock, cpu);
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+#endif
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struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
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int err;
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@@ -902,14 +908,18 @@ static int takedown_cpu(unsigned int cpu
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*/
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irq_lock_sparse();
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+#ifdef CONFIG_PREEMPT_RT_FULL
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__write_rt_lock(cpuhp_pin);
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+#endif
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/*
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* So now all preempt/rcu users must observe !cpu_active().
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*/
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err = stop_machine_cpuslocked(take_cpu_down, NULL, cpumask_of(cpu));
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if (err) {
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+#ifdef CONFIG_PREEMPT_RT_FULL
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__write_rt_unlock(cpuhp_pin);
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+#endif
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/* CPU refused to die */
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irq_unlock_sparse();
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/* Unpark the hotplug thread so we can rollback there */
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@@ -928,7 +938,9 @@ static int takedown_cpu(unsigned int cpu
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wait_for_ap_thread(st, false);
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BUG_ON(st->state != CPUHP_AP_IDLE_DEAD);
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+#ifdef CONFIG_PREEMPT_RT_FULL
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__write_rt_unlock(cpuhp_pin);
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+#endif
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/* Interrupts are moved away from the dying cpu, reenable alloc/free */
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irq_unlock_sparse();
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