Merge branch 'af_unix-fix-regression-by-the-per-netns-hash-table-series'

Kuniyuki Iwashima says:

====================
af_unix: Fix regression by the per-netns hash table series.

The series 6dd4142fb5a9 ("Merge branch 'af_unix-per-netns-socket-hash'")
replaced a global hash table with per-netns tables, which caused regression
reported in the links below. [0][1]

When a pathname socket is visible, any socket with the same type has to be
able to connect to it even in different netns.  The series puts all sockets
into each namespace's hash table, making it impossible to look up a visible
socket in different netns.

On the other hand, while dumping sockets, they are filtered by netns.  To
keep such code simple, let's add a new global hash table only for pathname
sockets and link them with sk_bind_node.  Then we can keep all sockets in
each per-netns table and look up pathname sockets via the global table.

[0]: https://lore.kernel.org/netdev/B2AA3091-796D-475E-9A11-0021996E1C00@linux.ibm.com/
[1]: https://lore.kernel.org/netdev/5fb8d86f-b633-7552-8ba9-41e42f07c02a@gmail.com/

Changes:
  v3:
    * 1st: Update changelog s/named/pathname/
    * 2nd: Fix checkpatch.pl CHECK by --strict option

  v2: https://lore.kernel.org/netdev/20220702014447.93746-1-kuniyu@amazon.com/
    * Add selftest

  v1: https://lore.kernel.org/netdev/20220701072519.96097-1-kuniyu@amazon.com/
====================

Link: https://lore.kernel.org/r/20220702154818.66761-1-kuniyu@amazon.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>