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Message-ID: <4AF45796.8010409@gmail.com>
Date: Fri, 06 Nov 2009 18:06:30 +0100
From: Eric Dumazet <eric.dumazet@...il.com>
To: David Miller <davem@...emloft.net>
CC: Lucian Adrian Grijincu <lgrijincu@...acom.com>,
netdev@...r.kernel.org, opurdila@...acom.com
Subject: [PATCH net-next-2.6 take2] ipv6: udp: Optimise multicast reception
Take 2 of patch, adding a missing kfree_skb() in case no socket could receive a copy
[PATCH net-next-2.6 take2] ipv6: udp: Optimise multicast reception
IPV6 UDP multicast rx path is a bit complex and can hold a spinlock
for a long time.
Using a small (32 or 64 entries) stack of socket pointers can help
to perform expensive operations (skb_clone(), udp_queue_rcv_skb())
outside of the lock, in most cases.
Signed-off-by: Eric Dumazet <eric.dumazet@...il.com>
---
net/ipv6/udp.c | 71 +++++++++++++++++++++++++++++++----------------
1 files changed, 47 insertions(+), 24 deletions(-)
diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index 5bc7cdb..ecb6a6f 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -440,6 +440,27 @@ static struct sock *udp_v6_mcast_next(struct net *net, struct sock *sk,
return NULL;
}
+static void flush_stack(struct sock **stack, unsigned int count,
+ struct sk_buff *skb, unsigned int final)
+{
+ unsigned int i;
+ struct sock *sk;
+ struct sk_buff *skb1;
+
+ for (i = 0; i < count; i++) {
+ skb1 = (i == final) ? skb : skb_clone(skb, GFP_ATOMIC);
+
+ if (skb1) {
+ sk = stack[i];
+ bh_lock_sock(sk);
+ if (!sock_owned_by_user(sk))
+ udpv6_queue_rcv_skb(sk, skb1);
+ else
+ sk_add_backlog(sk, skb1);
+ bh_unlock_sock(sk);
+ }
+ }
+}
/*
* Note: called only from the BH handler context,
* so we don't need to lock the hashes.
@@ -448,41 +469,43 @@ static int __udp6_lib_mcast_deliver(struct net *net, struct sk_buff *skb,
struct in6_addr *saddr, struct in6_addr *daddr,
struct udp_table *udptable)
{
- struct sock *sk, *sk2;
+ struct sock *sk, *stack[256 / sizeof(struct sock *)];
const struct udphdr *uh = udp_hdr(skb);
struct udp_hslot *hslot = udp_hashslot(udptable, net, ntohs(uh->dest));
int dif;
+ unsigned int i, count = 0;
spin_lock(&hslot->lock);
sk = sk_nulls_head(&hslot->head);
dif = inet6_iif(skb);
sk = udp_v6_mcast_next(net, sk, uh->dest, daddr, uh->source, saddr, dif);
- if (!sk) {
- kfree_skb(skb);
- goto out;
- }
-
- sk2 = sk;
- while ((sk2 = udp_v6_mcast_next(net, sk_nulls_next(sk2), uh->dest, daddr,
- uh->source, saddr, dif))) {
- struct sk_buff *buff = skb_clone(skb, GFP_ATOMIC);
- if (buff) {
- bh_lock_sock(sk2);
- if (!sock_owned_by_user(sk2))
- udpv6_queue_rcv_skb(sk2, buff);
- else
- sk_add_backlog(sk2, buff);
- bh_unlock_sock(sk2);
+ while (sk) {
+ stack[count++] = sk;
+ sk = udp_v6_mcast_next(net, sk_nulls_next(sk), uh->dest, daddr,
+ uh->source, saddr, dif);
+ if (unlikely(count == ARRAY_SIZE(stack))) {
+ if (!sk)
+ break;
+ flush_stack(stack, count, skb, ~0);
+ count = 0;
}
}
- bh_lock_sock(sk);
- if (!sock_owned_by_user(sk))
- udpv6_queue_rcv_skb(sk, skb);
- else
- sk_add_backlog(sk, skb);
- bh_unlock_sock(sk);
-out:
+ /*
+ * before releasing the lock, we must take reference on sockets
+ */
+ for (i = 0; i < count; i++)
+ sock_hold(stack[i]);
+
spin_unlock(&hslot->lock);
+
+ if (count) {
+ flush_stack(stack, count, skb, count - 1);
+
+ for (i = 0; i < count; i++)
+ sock_put(stack[i]);
+ } else {
+ kfree_skb(skb);
+ }
return 0;
}
--
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