From c25eb3bfb97294d0543a81230fbc237046b4b84c Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Sun, 23 Nov 2008 17:22:55 -0800 Subject: net: Convert TCP/DCCP listening hash tables to use RCU This is the last step to be able to perform full RCU lookups in __inet_lookup() : After established/timewait tables, we add RCU lookups to listening hash table. The only trick here is that a socket of a given type (TCP ipv4, TCP ipv6, ...) can now flight between two different tables (established and listening) during a RCU grace period, so we must use different 'nulls' end-of-chain values for two tables. We define a large value : #define LISTENING_NULLS_BASE (1U << 29) So that slots in listening table are guaranteed to have different end-of-chain values than slots in established table. A reader can still detect it finished its lookup in the right chain. Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller --- net/ipv4/tcp_ipv4.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) (limited to 'net/ipv4/tcp_ipv4.c') diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c index a81caa1be0cf..cab2458f86fd 100644 --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -1868,7 +1868,7 @@ static inline struct inet_timewait_sock *tw_next(struct inet_timewait_sock *tw) static void *listening_get_next(struct seq_file *seq, void *cur) { struct inet_connection_sock *icsk; - struct hlist_node *node; + struct hlist_nulls_node *node; struct sock *sk = cur; struct inet_listen_hashbucket *ilb; struct tcp_iter_state *st = seq->private; @@ -1878,7 +1878,7 @@ static void *listening_get_next(struct seq_file *seq, void *cur) st->bucket = 0; ilb = &tcp_hashinfo.listening_hash[0]; spin_lock_bh(&ilb->lock); - sk = sk_head(&ilb->head); + sk = sk_nulls_head(&ilb->head); goto get_sk; } ilb = &tcp_hashinfo.listening_hash[st->bucket]; @@ -1914,7 +1914,7 @@ get_req: sk = sk_next(sk); } get_sk: - sk_for_each_from(sk, node) { + sk_nulls_for_each_from(sk, node) { if (sk->sk_family == st->family && net_eq(sock_net(sk), net)) { cur = sk; goto out; @@ -1935,7 +1935,7 @@ start_req: if (++st->bucket < INET_LHTABLE_SIZE) { ilb = &tcp_hashinfo.listening_hash[st->bucket]; spin_lock_bh(&ilb->lock); - sk = sk_head(&ilb->head); + sk = sk_nulls_head(&ilb->head); goto get_sk; } cur = NULL; -- cgit v1.2.3