tcp: md5: remove spinlock usage in fast path
TCP md5 code uses per cpu variables but protects access to them with
a shared spinlock, which is a contention point.
[ tcp_md5sig_pool_lock is locked twice per incoming packet ]
Makes things much simpler, by allocating crypto structures once, first
time a socket needs md5 keys, and not deallocating them as they are
really small.
Next step would be to allow crypto allocations being done in a NUMA
aware way.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 7196523..d20ede0 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -1026,7 +1026,7 @@
key = sock_kmalloc(sk, sizeof(*key), gfp);
if (!key)
return -ENOMEM;
- if (hlist_empty(&md5sig->head) && !tcp_alloc_md5sig_pool(sk)) {
+ if (!tcp_alloc_md5sig_pool()) {
sock_kfree_s(sk, key, sizeof(*key));
return -ENOMEM;
}
@@ -1044,9 +1044,7 @@
int tcp_md5_do_del(struct sock *sk, const union tcp_md5_addr *addr, int family)
{
- struct tcp_sock *tp = tcp_sk(sk);
struct tcp_md5sig_key *key;
- struct tcp_md5sig_info *md5sig;
key = tcp_md5_do_lookup(sk, (union tcp_md5_addr *)&addr, AF_INET);
if (!key)
@@ -1054,10 +1052,6 @@
hlist_del_rcu(&key->node);
atomic_sub(sizeof(*key), &sk->sk_omem_alloc);
kfree_rcu(key, rcu);
- md5sig = rcu_dereference_protected(tp->md5sig_info,
- sock_owned_by_user(sk));
- if (hlist_empty(&md5sig->head))
- tcp_free_md5sig_pool();
return 0;
}
EXPORT_SYMBOL(tcp_md5_do_del);
@@ -1071,8 +1065,6 @@
md5sig = rcu_dereference_protected(tp->md5sig_info, 1);
- if (!hlist_empty(&md5sig->head))
- tcp_free_md5sig_pool();
hlist_for_each_entry_safe(key, n, &md5sig->head, node) {
hlist_del_rcu(&key->node);
atomic_sub(sizeof(*key), &sk->sk_omem_alloc);
