[RFC v2 PATCH 0/4] futex: Add support task local hash maps.

[Sebastian Andrzej Siewior]

Hi,

this is a follow up on
	https://lore.kernel.org/ZwVOMgBMxrw7BU9A@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

and adds support for task local futex_hash_bucket. It can be created via
prctl(). Last patch in the series enables it one the first thread is
created.

I've been how this auto-create behaves and so far dpkg creates threads
and uses the local-hashmap. systemd-journal on the hand forks a thread
from time to time and I haven't seen it using the hashmap. Need to do
more testing.

v1…v2 https://lore.kernel.org/all/20241026224306.982896-1-bigeasy@xxxxxxxxxxxxx/:
  - Moved to struct signal_struct and is used process wide.
  - Automaticly allocated once the first thread is created.

Sebastian