tcp/dccp: install syn_recv requests into ehash table
In this patch, we insert request sockets into TCP/DCCP
regular ehash table (where ESTABLISHED and TIMEWAIT sockets
are) instead of using the per listener hash table.
ACK packets find SYN_RECV pseudo sockets without having
to find and lock the listener.
In nominal conditions, this halves pressure on listener lock.
Note that this will allow for SO_REUSEPORT refinements,
so that we can select a listener using cpu/numa affinities instead
of the prior 'consistent hash', since only SYN packets will
apply this selection logic.
We will shrink listen_sock in the following patch to ease
code review.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Ying Cai <ycai@google.com>
Cc: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/inet_hashtables.c b/net/ipv4/inet_hashtables.c
index 56742e9..bed8886 100644
--- a/net/ipv4/inet_hashtables.c
+++ b/net/ipv4/inet_hashtables.c
@@ -398,14 +398,18 @@
inet->inet_dport);
}
-void __inet_hash_nolisten(struct sock *sk, struct sock *osk)
+/* insert a socket into ehash, and eventually remove another one
+ * (The another one can be a SYN_RECV or TIMEWAIT
+ */
+int inet_ehash_insert(struct sock *sk, struct sock *osk)
{
struct inet_hashinfo *hashinfo = sk->sk_prot->h.hashinfo;
struct hlist_nulls_head *list;
struct inet_ehash_bucket *head;
spinlock_t *lock;
+ int ret = 0;
- WARN_ON(!sk_unhashed(sk));
+ WARN_ON_ONCE(!sk_unhashed(sk));
sk->sk_hash = sk_ehashfn(sk);
head = inet_ehash_bucket(hashinfo, sk->sk_hash);
@@ -419,6 +423,12 @@
sk_nulls_del_node_init_rcu(osk);
}
spin_unlock(lock);
+ return ret;
+}
+
+void __inet_hash_nolisten(struct sock *sk, struct sock *osk)
+{
+ inet_ehash_insert(sk, osk);
sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
}
EXPORT_SYMBOL_GPL(__inet_hash_nolisten);