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net: Convert TCP/DCCP listening hash tables to use RCU

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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>
This commit is contained in:
Eric Dumazet
2008-11-23 17:22:55 -08:00
committed by David S. Miller
parent 8c862c23e2
commit c25eb3bfb9
5 changed files with 145 additions and 114 deletions
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8
net/ipv4/tcp_ipv4.c
View File

@ -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;