Re: [patch V2 24/24] cpu/hotplug: Convert hotplug locking to percpu rwsem

[Michael Ellerman]

Thomas Gleixner <tglx@xxxxxxxxxxxxx> writes:

> On Wed, 10 May 2017, Michael Ellerman wrote:
>
>> Thomas Gleixner <tglx@xxxxxxxxxxxxx> writes:
>> 
>> > @@ -130,6 +130,7 @@ void __static_key_slow_inc(struct static
>> >  	 * the all CPUs, for that to be serialized against CPU hot-plug
>> >  	 * we need to avoid CPUs coming online.
>> >  	 */
>> > +	lockdep_assert_hotplug_held();
>> >  	jump_label_lock();
>> >  	if (atomic_read(&key->enabled) == 0) {
>> >  		atomic_set(&key->enabled, -1);
>> 
>> I seem to be hitting this assert from the ftrace event selftests,
>> enabled at boot with CONFIG_FTRACE_STARTUP_TEST=y, using next-20170509
>> (on powerpc).
>> 
>> The stupidly obvious (or perhaps obviously stupid) patch below fixes it:
>
> Kinda. There is more horror in that area lurking and I'm still trying to
> figure out all the convoluted call pathes.

OK thanks.

cheers