From 0b35f6031a00329800bacc04085188c300c3a4d8 Mon Sep 17 00:00:00 2001 From: Taehee Yoo Date: Wed, 19 Jul 2017 14:27:33 +0900 Subject: 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 Acked-by: Julian Anastasov Signed-off-by: Pablo Neira Ayuso --- net/netfilter/nfnetlink_queue.c | 2 -- 1 file changed, 2 deletions(-) (limited to 'net/netfilter/nfnetlink_queue.c') diff --git a/net/netfilter/nfnetlink_queue.c b/net/netfilter/nfnetlink_queue.c index 16fa04086880..7c543bfbf624 100644 --- a/net/netfilter/nfnetlink_queue.c +++ b/net/netfilter/nfnetlink_queue.c @@ -928,7 +928,6 @@ static unsigned int nfqnl_nf_hook_drop(struct net *net) unsigned int instances = 0; int i; - rcu_read_lock(); for (i = 0; i < INSTANCE_BUCKETS; i++) { struct nfqnl_instance *inst; struct hlist_head *head = &q->instance_table[i]; @@ -938,7 +937,6 @@ static unsigned int nfqnl_nf_hook_drop(struct net *net) instances++; } } - rcu_read_unlock(); return instances; } -- cgit v1.2.3-55-g7522