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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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4
net/ipv4/inet_diag.c
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@@ -720,13 +720,13 @@ static int inet_diag_dump(struct sk_buff *skb, struct netlink_callback *cb)
for (i = s_i; i < INET_LHTABLE_SIZE; i++) {
struct sock *sk;
struct hlist_node *node;
struct hlist_nulls_node *node;
struct inet_listen_hashbucket *ilb;
num = 0;
ilb = &hashinfo->listening_hash[i];
spin_lock_bh(&ilb->lock);
sk_for_each(sk, node, &ilb->head) {
sk_nulls_for_each(sk, node, &ilb->head) {
struct inet_sock *inet = inet_sk(sk);
if (num < s_num) {