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authorEric Dumazet <edumazet@google.com>2016-04-01 08:52:17 -0700
committerDavid S. Miller <davem@davemloft.net>2016-04-04 22:11:20 -0400
commit3b24d854cb35383c30642116e5992fd619bdc9bc (patch)
treea2a0c8c8ad3f7f974d6a9b11b17865edfb62d6d1 /net/ipv4/inet_hashtables.c
parentinet: reqsk_alloc() needs to take care of dead listeners (diff)
downloadlinux-dev-3b24d854cb35383c30642116e5992fd619bdc9bc.tar.xz
linux-dev-3b24d854cb35383c30642116e5992fd619bdc9bc.zip
tcp/dccp: do not touch listener sk_refcnt under synflood
When a SYNFLOOD targets a non SO_REUSEPORT listener, multiple cpus contend on sk->sk_refcnt and sk->sk_wmem_alloc changes. By letting listeners use SOCK_RCU_FREE infrastructure, we can relax TCP_LISTEN lookup rules and avoid touching sk_refcnt Note that we still use SLAB_DESTROY_BY_RCU rules for other sockets, only listeners are impacted by this change. Peak performance under SYNFLOOD is increased by ~33% : On my test machine, I could process 3.2 Mpps instead of 2.4 Mpps Most consuming functions are now skb_set_owner_w() and sock_wfree() contending on sk->sk_wmem_alloc when cooking SYNACK and freeing them. Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to '')
-rw-r--r--net/ipv4/inet_hashtables.c73
1 files changed, 25 insertions, 48 deletions
diff --git a/net/ipv4/inet_hashtables.c b/net/ipv4/inet_hashtables.c
index 387338d71dcd..98ba03b6f87d 100644
--- a/net/ipv4/inet_hashtables.c
+++ b/net/ipv4/inet_hashtables.c
@@ -198,13 +198,13 @@ static inline int compute_score(struct sock *sk, struct net *net,
}
/*
- * Don't inline this cruft. Here are some nice properties to exploit here. The
- * BSD API does not allow a listening sock to specify the remote port nor the
+ * Here are some nice properties to exploit here. The BSD API
+ * does not allow a listening sock to specify the remote port nor the
* remote address for the connection. So always assume those are both
* wildcarded during the search since they can never be otherwise.
*/
-
+/* called with rcu_read_lock() : No refcount taken on the socket */
struct sock *__inet_lookup_listener(struct net *net,
struct inet_hashinfo *hashinfo,
struct sk_buff *skb, int doff,
@@ -212,37 +212,27 @@ struct sock *__inet_lookup_listener(struct net *net,
const __be32 daddr, const unsigned short hnum,
const int dif)
{
- struct sock *sk, *result;
- struct hlist_nulls_node *node;
unsigned int hash = inet_lhashfn(net, hnum);
struct inet_listen_hashbucket *ilb = &hashinfo->listening_hash[hash];
- int score, hiscore, matches = 0, reuseport = 0;
- bool select_ok = true;
+ int score, hiscore = 0, matches = 0, reuseport = 0;
+ struct sock *sk, *result = NULL;
u32 phash = 0;
-begin:
- result = NULL;
- hiscore = 0;
- sk_nulls_for_each_rcu(sk, node, &ilb->head) {
+ sk_for_each_rcu(sk, &ilb->head) {
score = compute_score(sk, net, hnum, daddr, dif);
if (score > hiscore) {
- result = sk;
- hiscore = score;
reuseport = sk->sk_reuseport;
if (reuseport) {
phash = inet_ehashfn(net, daddr, hnum,
saddr, sport);
- if (select_ok) {
- struct sock *sk2;
- sk2 = reuseport_select_sock(sk, phash,
- skb, doff);
- if (sk2) {
- result = sk2;
- goto found;
- }
- }
+ result = reuseport_select_sock(sk, phash,
+ skb, doff);
+ if (result)
+ return result;
matches = 1;
}
+ result = sk;
+ hiscore = score;
} else if (score == hiscore && reuseport) {
matches++;
if (reciprocal_scale(phash, matches) == 0)
@@ -250,24 +240,6 @@ begin:
phash = next_pseudo_random32(phash);
}
}
- /*
- * if the nulls value we got at the end of this lookup is
- * not the expected one, we must restart lookup.
- * We probably met an item that was moved to another chain.
- */
- if (get_nulls_value(node) != hash + LISTENING_NULLS_BASE)
- goto begin;
- if (result) {
-found:
- if (unlikely(!atomic_inc_not_zero(&result->sk_refcnt)))
- result = NULL;
- else if (unlikely(compute_score(result, net, hnum, daddr,
- dif) < hiscore)) {
- sock_put(result);
- select_ok = false;
- goto begin;
- }
- }
return result;
}
EXPORT_SYMBOL_GPL(__inet_lookup_listener);
@@ -508,7 +480,8 @@ int __inet_hash(struct sock *sk, struct sock *osk,
if (err)
goto unlock;
}
- __sk_nulls_add_node_rcu(sk, &ilb->head);
+ hlist_add_head_rcu(&sk->sk_node, &ilb->head);
+ sock_set_flag(sk, SOCK_RCU_FREE);
sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
unlock:
spin_unlock(&ilb->lock);
@@ -535,20 +508,25 @@ void inet_unhash(struct sock *sk)
{
struct inet_hashinfo *hashinfo = sk->sk_prot->h.hashinfo;
spinlock_t *lock;
+ bool listener = false;
int done;
if (sk_unhashed(sk))
return;
- if (sk->sk_state == TCP_LISTEN)
+ if (sk->sk_state == TCP_LISTEN) {
lock = &hashinfo->listening_hash[inet_sk_listen_hashfn(sk)].lock;
- else
+ listener = true;
+ } else {
lock = inet_ehash_lockp(hashinfo, sk->sk_hash);
-
+ }
spin_lock_bh(lock);
if (rcu_access_pointer(sk->sk_reuseport_cb))
reuseport_detach_sock(sk);
- done = __sk_nulls_del_node_init_rcu(sk);
+ if (listener)
+ done = __sk_del_node_init(sk);
+ else
+ done = __sk_nulls_del_node_init_rcu(sk);
if (done)
sock_prot_inuse_add(sock_net(sk), sk->sk_prot, -1);
spin_unlock_bh(lock);
@@ -684,9 +662,8 @@ void inet_hashinfo_init(struct inet_hashinfo *h)
for (i = 0; i < INET_LHTABLE_SIZE; i++) {
spin_lock_init(&h->listening_hash[i].lock);
- INIT_HLIST_NULLS_HEAD(&h->listening_hash[i].head,
- i + LISTENING_NULLS_BASE);
- }
+ INIT_HLIST_HEAD(&h->listening_hash[i].head);
+ }
}
EXPORT_SYMBOL_GPL(inet_hashinfo_init);