From 3ab5aee7fe840b5b1b35a8d1ac11c3de5281e611 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Sun, 16 Nov 2008 19:40:17 -0800 Subject: net: Convert TCP & DCCP hash tables to use RCU / hlist_nulls RCU was added to UDP lookups, using a fast infrastructure : - sockets kmem_cache use SLAB_DESTROY_BY_RCU and dont pay the price of call_rcu() at freeing time. - hlist_nulls permits to use few memory barriers. This patch uses same infrastructure for TCP/DCCP established and timewait sockets. Thanks to SLAB_DESTROY_BY_RCU, no slowdown for applications using short lived TCP connections. A followup patch, converting rwlocks to spinlocks will even speedup this case. __inet_lookup_established() is pretty fast now we dont have to dirty a contended cache line (read_lock/read_unlock) Only established and timewait hashtable are converted to RCU (bind table and listen table are still using traditional locking) Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller --- net/ipv4/tcp_ipv4.c | 25 +++++++++++++------------ 1 file changed, 13 insertions(+), 12 deletions(-) (limited to 'net/ipv4/tcp_ipv4.c') diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c index d49233f409b..b2e3ab2287b 100644 --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -1857,16 +1857,16 @@ EXPORT_SYMBOL(tcp_v4_destroy_sock); #ifdef CONFIG_PROC_FS /* Proc filesystem TCP sock list dumping. */ -static inline struct inet_timewait_sock *tw_head(struct hlist_head *head) +static inline struct inet_timewait_sock *tw_head(struct hlist_nulls_head *head) { - return hlist_empty(head) ? NULL : + return hlist_nulls_empty(head) ? NULL : list_entry(head->first, struct inet_timewait_sock, tw_node); } static inline struct inet_timewait_sock *tw_next(struct inet_timewait_sock *tw) { - return tw->tw_node.next ? - hlist_entry(tw->tw_node.next, typeof(*tw), tw_node) : NULL; + return !is_a_nulls(tw->tw_node.next) ? + hlist_nulls_entry(tw->tw_node.next, typeof(*tw), tw_node) : NULL; } static void *listening_get_next(struct seq_file *seq, void *cur) @@ -1954,8 +1954,8 @@ static void *listening_get_idx(struct seq_file *seq, loff_t *pos) static inline int empty_bucket(struct tcp_iter_state *st) { - return hlist_empty(&tcp_hashinfo.ehash[st->bucket].chain) && - hlist_empty(&tcp_hashinfo.ehash[st->bucket].twchain); + return hlist_nulls_empty(&tcp_hashinfo.ehash[st->bucket].chain) && + hlist_nulls_empty(&tcp_hashinfo.ehash[st->bucket].twchain); } static void *established_get_first(struct seq_file *seq) @@ -1966,7 +1966,7 @@ static void *established_get_first(struct seq_file *seq) for (st->bucket = 0; st->bucket < tcp_hashinfo.ehash_size; ++st->bucket) { struct sock *sk; - struct hlist_node *node; + struct hlist_nulls_node *node; struct inet_timewait_sock *tw; rwlock_t *lock = inet_ehash_lockp(&tcp_hashinfo, st->bucket); @@ -1975,7 +1975,7 @@ static void *established_get_first(struct seq_file *seq) continue; read_lock_bh(lock); - sk_for_each(sk, node, &tcp_hashinfo.ehash[st->bucket].chain) { + sk_nulls_for_each(sk, node, &tcp_hashinfo.ehash[st->bucket].chain) { if (sk->sk_family != st->family || !net_eq(sock_net(sk), net)) { continue; @@ -2004,7 +2004,7 @@ static void *established_get_next(struct seq_file *seq, void *cur) { struct sock *sk = cur; struct inet_timewait_sock *tw; - struct hlist_node *node; + struct hlist_nulls_node *node; struct tcp_iter_state *st = seq->private; struct net *net = seq_file_net(seq); @@ -2032,11 +2032,11 @@ get_tw: return NULL; read_lock_bh(inet_ehash_lockp(&tcp_hashinfo, st->bucket)); - sk = sk_head(&tcp_hashinfo.ehash[st->bucket].chain); + sk = sk_nulls_head(&tcp_hashinfo.ehash[st->bucket].chain); } else - sk = sk_next(sk); + sk = sk_nulls_next(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)) goto found; } @@ -2375,6 +2375,7 @@ struct proto tcp_prot = { .sysctl_rmem = sysctl_tcp_rmem, .max_header = MAX_TCP_HEADER, .obj_size = sizeof(struct tcp_sock), + .slab_flags = SLAB_DESTROY_BY_RCU, .twsk_prot = &tcp_timewait_sock_ops, .rsk_prot = &tcp_request_sock_ops, .h.hashinfo = &tcp_hashinfo, -- cgit v1.2.3