Merge branch 'ipmr-remove-rwlocks'

Eric Dumazet says:

====================
ipmr: get rid of rwlocks

We need to get rid of rwlocks in networking stacks,
if read_lock() is (ab)used from softirq context.

As discussed recently [1], rwlock are unfair by design in this case,
and writers can starve and trigger soft lockups.

This series convert ipmr code (both IPv4 and IPv6 families)
to RCU and spinlocks.

[1] https://lkml.org/lkml/2022/6/17/272

v2: fixed two typos, and resent because patch 19/19
    did not make it to patchwork.
====================

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