netfilter: ipset: Fix data race between add and list header in all hash types

netfilter: ipset: Fix data race between add and list header in all hash types

The "ipset list -terse" command is actually a dump operation which
may run parallel with "ipset add" commands, which can trigger an
internal resizing of the hash type of sets just being dumped. However,
dumping just the header part of the set was not protected against
underlying resizing. Fix it by protecting the header dumping part
as well.

Fixes: c4c997839cf9 ("netfilter: ipset: Fix parallel resizing and listing of the same set")
Signed-off-by: Jozsef Kadlecsik <kadlec@netfilter.org>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>