udp: no longer use SLAB_DESTROY_BY_RCU
Tom Herbert would like not touching UDP socket refcnt for encapsulated
traffic. For this to happen, we need to use normal RCU rules, with a grace
period before freeing a socket. UDP sockets are not short lived in the
high usage case, so the added cost of call_rcu() should not be a concern.
This actually removes a lot of complexity in UDP stack.
Multicast receives no longer need to hold a bucket spinlock.
Note that ip early demux still needs to take a reference on the socket.
Same remark for functions used by xt_socket and xt_PROXY netfilter modules,
but this might be changed later.
Performance for a single UDP socket receiving flood traffic from
many RX queues/cpus.
Simple udp_rx using simple recvfrom() loop :
438 kpps instead of 374 kpps : 17 % increase of the peak rate.
v2: Addressed Willem de Bruijn feedback in multicast handling
- keep early demux break in __udp4_lib_demux_lookup()
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Tom Herbert <tom@herbertland.com>
Cc: Willem de Bruijn <willemb@google.com>
Tested-by: Tom Herbert <tom@herbertland.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index b772a76..78a7dfd 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -213,37 +213,28 @@
struct sk_buff *skb)
{
struct sock *sk, *result;
- struct hlist_nulls_node *node;
int score, badness, matches = 0, reuseport = 0;
- bool select_ok = true;
u32 hash = 0;
-begin:
result = NULL;
badness = -1;
- udp_portaddr_for_each_entry_rcu(sk, node, &hslot2->head) {
+ udp_portaddr_for_each_entry_rcu(sk, &hslot2->head) {
score = compute_score2(sk, net, saddr, sport,
daddr, hnum, dif);
if (score > badness) {
- result = sk;
- badness = score;
reuseport = sk->sk_reuseport;
if (reuseport) {
hash = udp6_ehashfn(net, daddr, hnum,
saddr, sport);
- if (select_ok) {
- struct sock *sk2;
- sk2 = reuseport_select_sock(sk, hash, skb,
+ result = reuseport_select_sock(sk, hash, skb,
sizeof(struct udphdr));
- if (sk2) {
- result = sk2;
- select_ok = false;
- goto found;
- }
- }
+ if (result)
+ return result;
matches = 1;
}
+ result = sk;
+ badness = score;
} else if (score == badness && reuseport) {
matches++;
if (reciprocal_scale(hash, matches) == 0)
@@ -251,27 +242,10 @@
hash = next_pseudo_random32(hash);
}
}
- /*
- * 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) != slot2)
- goto begin;
-
- if (result) {
-found:
- if (unlikely(!atomic_inc_not_zero_hint(&result->sk_refcnt, 2)))
- result = NULL;
- else if (unlikely(compute_score2(result, net, saddr, sport,
- daddr, hnum, dif) < badness)) {
- sock_put(result);
- goto begin;
- }
- }
return result;
}
+/* rcu_read_lock() must be held */
struct sock *__udp6_lib_lookup(struct net *net,
const struct in6_addr *saddr, __be16 sport,
const struct in6_addr *daddr, __be16 dport,
@@ -279,15 +253,12 @@
struct sk_buff *skb)
{
struct sock *sk, *result;
- struct hlist_nulls_node *node;
unsigned short hnum = ntohs(dport);
unsigned int hash2, slot2, slot = udp_hashfn(net, hnum, udptable->mask);
struct udp_hslot *hslot2, *hslot = &udptable->hash[slot];
int score, badness, matches = 0, reuseport = 0;
- bool select_ok = true;
u32 hash = 0;
- rcu_read_lock();
if (hslot->count > 10) {
hash2 = udp6_portaddr_hash(net, daddr, hnum);
slot2 = hash2 & udptable->mask;
@@ -309,34 +280,26 @@
&in6addr_any, hnum, dif,
hslot2, slot2, skb);
}
- rcu_read_unlock();
return result;
}
begin:
result = NULL;
badness = -1;
- sk_nulls_for_each_rcu(sk, node, &hslot->head) {
+ sk_for_each_rcu(sk, &hslot->head) {
score = compute_score(sk, net, hnum, saddr, sport, daddr, dport, dif);
if (score > badness) {
- result = sk;
- badness = score;
reuseport = sk->sk_reuseport;
if (reuseport) {
hash = udp6_ehashfn(net, daddr, hnum,
saddr, sport);
- if (select_ok) {
- struct sock *sk2;
-
- sk2 = reuseport_select_sock(sk, hash, skb,
+ result = reuseport_select_sock(sk, hash, skb,
sizeof(struct udphdr));
- if (sk2) {
- result = sk2;
- select_ok = false;
- goto found;
- }
- }
+ if (result)
+ return result;
matches = 1;
}
+ result = sk;
+ badness = score;
} else if (score == badness && reuseport) {
matches++;
if (reciprocal_scale(hash, matches) == 0)
@@ -344,25 +307,6 @@
hash = next_pseudo_random32(hash);
}
}
- /*
- * 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) != slot)
- goto begin;
-
- if (result) {
-found:
- if (unlikely(!atomic_inc_not_zero_hint(&result->sk_refcnt, 2)))
- result = NULL;
- else if (unlikely(compute_score(result, net, hnum, saddr, sport,
- daddr, dport, dif) < badness)) {
- sock_put(result);
- goto begin;
- }
- }
- rcu_read_unlock();
return result;
}
EXPORT_SYMBOL_GPL(__udp6_lib_lookup);
@@ -382,12 +326,24 @@
udptable, skb);
}
+/* Must be called under rcu_read_lock().
+ * Does increment socket refcount.
+ */
+#if IS_ENABLED(CONFIG_NETFILTER_XT_MATCH_SOCKET) || \
+ IS_ENABLED(CONFIG_NETFILTER_XT_TARGET_TPROXY)
struct sock *udp6_lib_lookup(struct net *net, const struct in6_addr *saddr, __be16 sport,
const struct in6_addr *daddr, __be16 dport, int dif)
{
- return __udp6_lib_lookup(net, saddr, sport, daddr, dport, dif, &udp_table, NULL);
+ struct sock *sk;
+
+ sk = __udp6_lib_lookup(net, saddr, sport, daddr, dport,
+ dif, &udp_table, NULL);
+ if (sk && !atomic_inc_not_zero(&sk->sk_refcnt))
+ sk = NULL;
+ return sk;
}
EXPORT_SYMBOL_GPL(udp6_lib_lookup);
+#endif
/*
* This should be easy, if there is something there we
@@ -585,7 +541,7 @@
sk->sk_err = err;
sk->sk_error_report(sk);
out:
- sock_put(sk);
+ return;
}
static int __udpv6_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
@@ -747,33 +703,6 @@
return true;
}
-static void flush_stack(struct sock **stack, unsigned int count,
- struct sk_buff *skb, unsigned int final)
-{
- struct sk_buff *skb1 = NULL;
- struct sock *sk;
- unsigned int i;
-
- for (i = 0; i < count; i++) {
- sk = stack[i];
- if (likely(!skb1))
- skb1 = (i == final) ? skb : skb_clone(skb, GFP_ATOMIC);
- if (!skb1) {
- atomic_inc(&sk->sk_drops);
- UDP6_INC_STATS_BH(sock_net(sk), UDP_MIB_RCVBUFERRORS,
- IS_UDPLITE(sk));
- UDP6_INC_STATS_BH(sock_net(sk), UDP_MIB_INERRORS,
- IS_UDPLITE(sk));
- }
-
- if (skb1 && udpv6_queue_rcv_skb(sk, skb1) <= 0)
- skb1 = NULL;
- sock_put(sk);
- }
- if (unlikely(skb1))
- kfree_skb(skb1);
-}
-
static void udp6_csum_zero_error(struct sk_buff *skb)
{
/* RFC 2460 section 8.1 says that we SHOULD log
@@ -792,15 +721,15 @@
const struct in6_addr *saddr, const struct in6_addr *daddr,
struct udp_table *udptable, int proto)
{
- struct sock *sk, *stack[256 / sizeof(struct sock *)];
+ struct sock *sk, *first = NULL;
const struct udphdr *uh = udp_hdr(skb);
- struct hlist_nulls_node *node;
unsigned short hnum = ntohs(uh->dest);
struct udp_hslot *hslot = udp_hashslot(udptable, net, hnum);
- int dif = inet6_iif(skb);
- unsigned int count = 0, offset = offsetof(typeof(*sk), sk_nulls_node);
+ unsigned int offset = offsetof(typeof(*sk), sk_node);
unsigned int hash2 = 0, hash2_any = 0, use_hash2 = (hslot->count > 10);
- bool inner_flushed = false;
+ int dif = inet6_iif(skb);
+ struct hlist_node *node;
+ struct sk_buff *nskb;
if (use_hash2) {
hash2_any = udp6_portaddr_hash(net, &in6addr_any, hnum) &
@@ -811,27 +740,32 @@
offset = offsetof(typeof(*sk), __sk_common.skc_portaddr_node);
}
- spin_lock(&hslot->lock);
- sk_nulls_for_each_entry_offset(sk, node, &hslot->head, offset) {
- if (__udp_v6_is_mcast_sock(net, sk,
- uh->dest, daddr,
- uh->source, saddr,
- dif, hnum) &&
- /* If zero checksum and no_check is not on for
- * the socket then skip it.
- */
- (uh->check || udp_sk(sk)->no_check6_rx)) {
- if (unlikely(count == ARRAY_SIZE(stack))) {
- flush_stack(stack, count, skb, ~0);
- inner_flushed = true;
- count = 0;
- }
- stack[count++] = sk;
- sock_hold(sk);
+ sk_for_each_entry_offset_rcu(sk, node, &hslot->head, offset) {
+ if (!__udp_v6_is_mcast_sock(net, sk, uh->dest, daddr,
+ uh->source, saddr, dif, hnum))
+ continue;
+ /* If zero checksum and no_check is not on for
+ * the socket then skip it.
+ */
+ if (!uh->check && !udp_sk(sk)->no_check6_rx)
+ continue;
+ if (!first) {
+ first = sk;
+ continue;
}
- }
+ nskb = skb_clone(skb, GFP_ATOMIC);
+ if (unlikely(!nskb)) {
+ atomic_inc(&sk->sk_drops);
+ UDP6_INC_STATS_BH(net, UDP_MIB_RCVBUFERRORS,
+ IS_UDPLITE(sk));
+ UDP6_INC_STATS_BH(net, UDP_MIB_INERRORS,
+ IS_UDPLITE(sk));
+ continue;
+ }
- spin_unlock(&hslot->lock);
+ if (udpv6_queue_rcv_skb(sk, nskb) > 0)
+ consume_skb(nskb);
+ }
/* Also lookup *:port if we are using hash2 and haven't done so yet. */
if (use_hash2 && hash2 != hash2_any) {
@@ -839,13 +773,13 @@
goto start_lookup;
}
- if (count) {
- flush_stack(stack, count, skb, count - 1);
+ if (first) {
+ if (udpv6_queue_rcv_skb(first, skb) > 0)
+ consume_skb(skb);
} else {
- if (!inner_flushed)
- UDP6_INC_STATS_BH(net, UDP_MIB_IGNOREDMULTI,
- proto == IPPROTO_UDPLITE);
- consume_skb(skb);
+ kfree_skb(skb);
+ UDP6_INC_STATS_BH(net, UDP_MIB_IGNOREDMULTI,
+ proto == IPPROTO_UDPLITE);
}
return 0;
}
@@ -853,10 +787,10 @@
int __udp6_lib_rcv(struct sk_buff *skb, struct udp_table *udptable,
int proto)
{
- struct net *net = dev_net(skb->dev);
- struct sock *sk;
- struct udphdr *uh;
const struct in6_addr *saddr, *daddr;
+ struct net *net = dev_net(skb->dev);
+ struct udphdr *uh;
+ struct sock *sk;
u32 ulen = 0;
if (!pskb_may_pull(skb, sizeof(struct udphdr)))
@@ -910,7 +844,6 @@
int ret;
if (!uh->check && !udp_sk(sk)->no_check6_rx) {
- sock_put(sk);
udp6_csum_zero_error(skb);
goto csum_error;
}
@@ -920,7 +853,6 @@
ip6_compute_pseudo);
ret = udpv6_queue_rcv_skb(sk, skb);
- sock_put(sk);
/* a return value > 0 means to resubmit the input */
if (ret > 0)