Merge branch 'udp-round-of-data-races-fixes'

Eric Dumazet says:

====================
udp: round of data-races fixes

This series is inspired by multiple syzbot reports.

Many udp fields reads or writes are racy.

Add a proper udp->udp_flags and move there all
flags needing atomic safety.

Also add missing READ_ONCE()/WRITE_ONCE() when
lockless readers need access to specific fields.
====================

Link: https://lore.kernel.org/r/20230912091730.1591459-1-edumazet@google.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>