diff options
Diffstat (limited to 'kernel/cpu.c')
| -rw-r--r-- | kernel/cpu.c | 67 |
1 files changed, 67 insertions, 0 deletions
diff --git a/kernel/cpu.c b/kernel/cpu.c index 59e418f192d2..edbb3edc6d83 100644 --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -75,6 +75,11 @@ static DEFINE_PER_CPU(struct cpuhp_cpu_state, cpuhp_state) = { .fail = CPUHP_INVALID, }; +#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 + #if defined(CONFIG_LOCKDEP) && defined(CONFIG_SMP) static struct lockdep_map cpuhp_state_up_map = STATIC_LOCKDEP_MAP_INIT("cpuhp_state-up", &cpuhp_state_up_map); @@ -284,6 +289,55 @@ static int cpu_hotplug_disabled; #ifdef CONFIG_HOTPLUG_CPU +/** + * pin_current_cpu - Prevent the current cpu from being unplugged + */ +void pin_current_cpu(void) +{ +#ifdef CONFIG_PREEMPT_RT_FULL + struct rt_rw_lock *cpuhp_pin; + unsigned int cpu; + int ret; + +again: + cpuhp_pin = this_cpu_ptr(&cpuhp_pin_lock); + ret = __read_rt_trylock(cpuhp_pin); + if (ret) { + current->pinned_on_cpu = smp_processor_id(); + return; + } + cpu = smp_processor_id(); + preempt_lazy_enable(); + preempt_enable(); + + __read_rt_lock(cpuhp_pin); + + preempt_disable(); + preempt_lazy_disable(); + if (cpu != smp_processor_id()) { + __read_rt_unlock(cpuhp_pin); + goto again; + } + current->pinned_on_cpu = cpu; +#endif +} + +/** + * unpin_current_cpu - Allow unplug of current cpu + */ +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())) + cpuhp_pin = per_cpu_ptr(&cpuhp_pin_lock, current->pinned_on_cpu); + + current->pinned_on_cpu = -1; + __read_rt_unlock(cpuhp_pin); +#endif +} + DEFINE_STATIC_PERCPU_RWSEM(cpu_hotplug_lock); void cpus_read_lock(void) @@ -871,6 +925,9 @@ 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; @@ -883,11 +940,18 @@ 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 */ @@ -906,6 +970,9 @@ 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(); |