Re: [PATCH v1] drivers/acpi/scan.c: Fixup "acquire device_hotplug_lock in acpi_scan_init()"

David Hildenbrand
2019-07-31T13:02:54Z

On 31.07.19 14:53, Michal Hocko wrote:
> On Wed 31-07-19 14:32:01, David Hildenbrand wrote:
>> Let's document why we take the lock here. If we're going to overhaul
>> memory hotplug locking, we'll have to touch many places - this comment
>> will help to clairfy why it was added here.
>
> And how exactly is "lock for consistency" comment going to help the poor
> soul touching that code? How do people know that it is safe to remove it?
> I am not going to repeat my arguments how/why I hate "locking for
> consistency" (or fun or whatever but a real synchronization reasons)
> but if you want to help then just explicitly state what should done to
> remove this lock.
>

I know that you have a different opinion here. To remove the lock,
add_memory() locking has to be changed *completely* to the point where
we can drop the lock from the documentation of the function (*whoever
knows what we have to exactly change* - and I don't have time to do that
*right now*).

--

Thanks,

David / dhildenb