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authorTaehee Yoo <ap420073@gmail.com>2017-07-19 14:27:33 +0900
committerPablo Neira Ayuso <pablo@netfilter.org>2017-07-24 13:24:46 +0200
commit0b35f6031a00329800bacc04085188c300c3a4d8 (patch)
treeb4e34d6ab10b8b065583f1ce7c75ec05dea5a107 /net/netfilter/xt_TCPMSS.c
parent9f08ea848117ab521efcfd3e004d8e1a0edc640c (diff)
netfilter: Remove duplicated rcu_read_lock.
This patch removes duplicate rcu_read_lock(). 1. IPVS part: According to Julian Anastasov's mention, contexts of ipvs are described at: http://marc.info/?l=netfilter-devel&m=149562884514072&w=2, in summary: - packet RX/TX: does not need locks because packets come from hooks. - sync msg RX: backup server uses RCU locks while registering new connections. - ip_vs_ctl.c: configuration get/set, RCU locks needed. - xt_ipvs.c: It is a netfilter match, running from hook context. As result, rcu_read_lock and rcu_read_unlock can be removed from: - ip_vs_core.c: all - ip_vs_ctl.c: - only from ip_vs_has_real_service - ip_vs_ftp.c: all - ip_vs_proto_sctp.c: all - ip_vs_proto_tcp.c: all - ip_vs_proto_udp.c: all - ip_vs_xmit.c: all (contains only packet processing) 2. Netfilter part: There are three types of functions that are guaranteed the rcu_read_lock(). First, as result, functions are only called by nf_hook(): - nf_conntrack_broadcast_help(), pptp_expectfn(), set_expected_rtp_rtcp(). - tcpmss_reverse_mtu(), tproxy_laddr4(), tproxy_laddr6(). - match_lookup_rt6(), check_hlist(), hashlimit_mt_common(). - xt_osf_match_packet(). Second, functions that caller already held the rcu_read_lock(). - destroy_conntrack(), ctnetlink_conntrack_event(). - ctnl_timeout_find_get(), nfqnl_nf_hook_drop(). Third, functions that are mixed with type1 and type2. These functions are called by nf_hook() also these are called by ordinary functions that already held the rcu_read_lock(): - __ctnetlink_glue_build(), ctnetlink_expect_event(). - ctnetlink_proto_size(). Applied files are below: - nf_conntrack_broadcast.c, nf_conntrack_core.c, nf_conntrack_netlink.c. - nf_conntrack_pptp.c, nf_conntrack_sip.c, nfnetlink_cttimeout.c. - nfnetlink_queue.c, xt_TCPMSS.c, xt_TPROXY.c, xt_addrtype.c. - xt_connlimit.c, xt_hashlimit.c, xt_osf.c Detailed calltrace can be found at: http://marc.info/?l=netfilter-devel&m=149667610710350&w=2 Signed-off-by: Taehee Yoo <ap420073@gmail.com> Acked-by: Julian Anastasov <ja@ssi.bg> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Diffstat (limited to 'net/netfilter/xt_TCPMSS.c')
-rw-r--r--net/netfilter/xt_TCPMSS.c2
1 files changed, 0 insertions, 2 deletions
diff --git a/net/netfilter/xt_TCPMSS.c b/net/netfilter/xt_TCPMSS.c
index c64aca611ac5..9dae4d665965 100644
--- a/net/netfilter/xt_TCPMSS.c
+++ b/net/netfilter/xt_TCPMSS.c
@@ -62,11 +62,9 @@ static u_int32_t tcpmss_reverse_mtu(struct net *net,
memset(fl6, 0, sizeof(*fl6));
fl6->daddr = ipv6_hdr(skb)->saddr;
}
- rcu_read_lock();
ai = nf_get_afinfo(family);
if (ai != NULL)
ai->route(net, (struct dst_entry **)&rt, &fl, false);
- rcu_read_unlock();
if (rt != NULL) {
mtu = dst_mtu(&rt->dst);