xchg
prev_hang = xchg(&file_priv->hang_timestamp, jiffies);
fence = xchg(&cb->base.fence, NULL);
fence = xchg(&cb->base.fence, NULL);
WARN_ON_ONCE(xchg(&db->cookie, cookie + 1 ?: cookie + 2) != cookie);
if (xchg(&domain->active, false))
xchg(ip6->ip6_dst, ip6->ip6_src, struct in6_addr);
xchg(ip->ip_dst.s_addr, ip->ip_src.s_addr, n_long);
xchg(nth->th_dport, nth->th_sport, n_short);