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Message-ID: <4AF727AC.4010904@gmail.com> Date: Sun, 08 Nov 2009 21:18:52 +0100 From: Eric Dumazet <eric.dumazet@...il.com> To: "David S. Miller" <davem@...emloft.net> CC: Linux Netdev List <netdev@...r.kernel.org>, Lucian Adrian Grijincu <lgrijincu@...acom.com>, Octavian Purdila <opurdila@...acom.com> Subject: [PATCH 7/8] 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 c5b0451..173e531 100644 --- a/net/ipv6/udp.c +++ b/net/ipv6/udp.c @@ -569,6 +569,27 @@ 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. @@ -577,41 +598,43 @@ 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; } -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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