Similar to the previous patch, plumb the RCU lock inside
the ipmr_get_table(), provided a lockless variant and apply
the latter in the few spots were the lock is already held.
Fixes: 709b46e8d90b ("net: Add compat ioctl support for the ipv4 multicast ioctl SIOCGETSGCNT") Fixes: f0ad0860d01e ("ipv4: ipmr: support multiple tables") Reviewed-by: David Ahern <dsahern@kernel.org> Signed-off-by: Paolo Abeni <pabeni@redhat.com>