On Tue, 04 Dec 2012 14:24:28 +0530 "Srivatsa S. Bhat" <[email protected]> wrote:
> From: Michael Wang <[email protected]> > > With stop_machine() gone from the CPU offline path, we can't depend on > preempt_disable() to prevent CPUs from going offline from under us. > > Use the get/put_online_cpus_stable_atomic() APIs to prevent CPUs from going > offline, while invoking from atomic context. > > ... > > */ > - this_cpu = get_cpu(); > + get_online_cpus_stable_atomic(); > + this_cpu = smp_processor_id(); I wonder if get_online_cpus_stable_atomic() should return the local CPU ID. Just as a little convenience thing. Time will tell. > /* > * Can deadlock when called with interrupts disabled. > > ... > > @@ -380,15 +383,15 @@ int smp_call_function_any(const struct cpumask *mask, > nodemask = cpumask_of_node(cpu_to_node(cpu)); > for (cpu = cpumask_first_and(nodemask, mask); cpu < nr_cpu_ids; > cpu = cpumask_next_and(cpu, nodemask, mask)) { > - if (cpu_online(cpu)) > + if (cpu_online_stable(cpu)) > goto call; > } > > /* Any online will do: smp_call_function_single handles nr_cpu_ids. */ > - cpu = cpumask_any_and(mask, cpu_online_mask); > + cpu = cpumask_any_and(mask, cpu_online_stable_mask); > call: > ret = smp_call_function_single(cpu, func, info, wait); > - put_cpu(); > + put_online_cpus_stable_atomic(); > return ret; > } > EXPORT_SYMBOL_GPL(smp_call_function_any); So smp_call_function_any() has no synchronization against CPUs coming online. Hence callers of smp_call_function_any() are responsible for ensuring that CPUs which are concurrently coming online will adopt the required state? I guess that has always been the case... > > ... > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
