Commit cd3c7480 authored by Pavel Begunkov's avatar Pavel Begunkov Committed by Jakub Kicinski
Browse files

ipv6: optimise dst refcounting on skb init 



__ip6_make_skb() gets a cork->dst ref, hands it over to skb and shortly
after puts cork->dst. Save two atomics by stealing it without extra
referencing, ip6_cork_release() handles NULL cork->dst.

Signed-off-by: default avatarPavel Begunkov <asml.silence@gmail.com>
Reviewed-by: default avatarWillem de Bruijn <willemb@google.com>
Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent d344e553

net/ipv6/ip6_output.c

+10 −1
Original line number Diff line number Diff line
@@ -1807,6 +1807,15 @@ int ip6_append_data(struct sock *sk, 
}

EXPORT_SYMBOL_GPL(ip6_append_data);



static void ip6_cork_steal_dst(struct sk_buff *skb, struct inet_cork_full *cork)

{

	struct dst_entry *dst = cork->base.dst;



	cork->base.dst = NULL;

	cork->base.flags &= ~IPCORK_ALLFRAG;

	skb_dst_set(skb, dst);

}



static void ip6_cork_release(struct inet_cork_full *cork,

			     struct inet6_cork *v6_cork)

{
@@ -1889,7 +1898,7 @@ struct sk_buff *__ip6_make_skb(struct sock *sk, 


	skb->tstamp = cork->base.transmit_time;



	skb_dst_set(skb, dst_clone(&rt->dst));

	ip6_cork_steal_dst(skb, cork);

	IP6_UPD_PO_STATS(net, rt->rt6i_idev, IPSTATS_MIB_OUT, skb->len);

	if (proto == IPPROTO_ICMPV6) {

		struct inet6_dev *idev = ip6_dst_idev(skb_dst(skb));