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 <dada1@cosmosbay.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index d49233f..b2e3ab2 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -1857,16 +1857,16 @@
#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 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 @@
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 @@
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 @@
{
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 @@
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 @@
.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,