netfilter: ipset: fix race condition between swap/destroy and kernel side add/del/test
JIRA: https://issues.redhat.com/browse/RHEL-30522 Upstream Status: All upstream in linus.git
Patch 1 fixes the reported crash, patch 2 restores performance and patch 3 fixes patch 2.
Signed-off-by: Phil Sutter psutter@redhat.com