From 3ed5cb0e7f86a61b58b20f64a79148a2a80dac29 Mon Sep 17 00:00:00 2001 From: Sebastian Andrzej Siewior Date: Fri, 4 Aug 2017 18:31:00 +0200 Subject: [PATCH 230/347] hotplug: duct-tape RT-rwlock usage for non-RT Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.19/older/patches-4.19.246-rt110.tar.xz 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 --- kernel/cpu.c | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-) diff --git a/kernel/cpu.c b/kernel/cpu.c index 797216a0b4c6..f6511c62c9a4 100644 --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -77,7 +77,7 @@ 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 @@ -293,6 +293,7 @@ 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; @@ -315,6 +316,7 @@ void pin_current_cpu(void) goto again; } current->pinned_on_cpu = cpu; +#endif } /** @@ -322,6 +324,7 @@ 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())) @@ -329,6 +332,7 @@ void unpin_current_cpu(void) current->pinned_on_cpu = -1; __read_rt_unlock(cpuhp_pin); +#endif } DEFINE_STATIC_PERCPU_RWSEM(cpu_hotplug_lock); @@ -953,7 +957,9 @@ 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; @@ -966,14 +972,18 @@ 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 */ @@ -992,7 +1002,9 @@ 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(); -- 2.36.1