| From: Sebastian Andrzej Siewior <bigeasy@linutronix.de> |
| Date: Fri, 4 Aug 2017 18:31:00 +0200 |
| Subject: [PATCH] hotplug: duct-tape RT-rwlock usage for non-RT |
| |
| 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(-) |
| |
| --- a/kernel/cpu.c |
| +++ b/kernel/cpu.c |
| @@ -66,7 +66,7 @@ struct cpuhp_cpu_state { |
| |
| static DEFINE_PER_CPU(struct cpuhp_cpu_state, cpuhp_state); |
| |
| -#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 |
| @@ -221,6 +221,7 @@ 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; |
| @@ -245,6 +246,7 @@ void pin_current_cpu(void) |
| goto again; |
| } |
| current->pinned_on_cpu = cpu; |
| +#endif |
| } |
| |
| /** |
| @@ -252,6 +254,7 @@ 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())) |
| @@ -259,6 +262,7 @@ void unpin_current_cpu(void) |
| |
| current->pinned_on_cpu = -1; |
| __read_rt_unlock(cpuhp_pin); |
| +#endif |
| } |
| |
| DEFINE_STATIC_PERCPU_RWSEM(cpu_hotplug_lock); |
| @@ -679,7 +683,9 @@ 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; |
| |
| @@ -693,14 +699,18 @@ 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 */ |
| @@ -719,7 +729,9 @@ static int takedown_cpu(unsigned int cpu |
| wait_for_completion(&st->done); |
| 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(); |
| |