Merge branch 'af_unix-OOB-fixes'

Kuniyuki Iwashima says:

====================
af_unix: Fix some OOB implementation.

This series fixes some data-races and adds a missing feature around the
commit 314001f0

 ("af_unix: Add OOB support").

Changelog:
  - v3:
    - Add the first patch

  - v2: https://lore.kernel.org/netdev/20220315054801.72035-1-kuniyu@amazon.co.jp/
    - Add READ_ONCE() to avoid a race reported by KCSAN (Eric)
    - Add IS_ENABLED(CONFIG_AF_UNIX_OOB) (Shoaib)

  - v1: https://lore.kernel.org/netdev/20220314052110.53634-1-kuniyu@amazon.co.jp/
====================

Signed-off-by: David S. Miller <davem@davemloft.net>