diff options
Diffstat (limited to 'kernel/cpu.c')
| -rw-r--r-- | kernel/cpu.c | 26 |
1 files changed, 20 insertions, 6 deletions
diff --git a/kernel/cpu.c b/kernel/cpu.c index b2b227b8212..63aa50d7ce1 100644 --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -113,7 +113,7 @@ EXPORT_SYMBOL_GPL(put_online_cpus); * get_online_cpus() not an api which is called all that often. * */ -static void cpu_hotplug_begin(void) +void cpu_hotplug_begin(void) { cpu_hotplug.active_writer = current; @@ -127,7 +127,7 @@ static void cpu_hotplug_begin(void) } } -static void cpu_hotplug_done(void) +void cpu_hotplug_done(void) { cpu_hotplug.active_writer = NULL; mutex_unlock(&cpu_hotplug.lock); @@ -154,10 +154,7 @@ void cpu_hotplug_enable(void) cpu_maps_update_done(); } -#else /* #if CONFIG_HOTPLUG_CPU */ -static void cpu_hotplug_begin(void) {} -static void cpu_hotplug_done(void) {} -#endif /* #else #if CONFIG_HOTPLUG_CPU */ +#endif /* CONFIG_HOTPLUG_CPU */ /* Need to know about CPUs going up/down? */ int __ref register_cpu_notifier(struct notifier_block *nb) @@ -311,6 +308,23 @@ static int __ref _cpu_down(unsigned int cpu, int tasks_frozen) } smpboot_park_threads(cpu); + /* + * By now we've cleared cpu_active_mask, wait for all preempt-disabled + * and RCU users of this state to go away such that all new such users + * will observe it. + * + * For CONFIG_PREEMPT we have preemptible RCU and its sync_rcu() might + * not imply sync_sched(), so explicitly call both. + */ +#ifdef CONFIG_PREEMPT + synchronize_sched(); +#endif + synchronize_rcu(); + + /* + * So now all preempt/rcu users must observe !cpu_active(). + */ + err = __stop_machine(take_cpu_down, &tcd_param, cpumask_of(cpu)); if (err) { /* CPU didn't die: tell everyone. Can't complain. */ |