Merge branch 'small-api-fix-for-bpf_wq'

Benjamin Tissoires says:

====================
Small API fix for bpf_wq

I realized this while having a map containing both a struct bpf_timer and
a struct bpf_wq: the third argument provided to the bpf_wq callback is
not the struct bpf_wq pointer itself, but the pointer to the value in
the map.

Which means that the users need to double cast the provided "value" as
this is not a struct bpf_wq *.

This is a change of API, but there doesn't seem to be much users of bpf_wq
right now, so we should be able to go with this right now.

Signed-off-by: Benjamin Tissoires <bentiss@kernel.org>
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Changes in v2:
- amended the selftests to retrieve something from the third argument of
  the callback
- Link to v1: https://lore.kernel.org/r/20240705-fix-wq-v1-0-91b4d82cd825@kernel.org

---
====================

Link: https://lore.kernel.org/r/20240708-fix-wq-v2-0-667e5c9fbd99@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>