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 <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 a81caa1..cab2458 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -1868,7 +1868,7 @@
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 @@
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 @@
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 @@
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;