Netdev Archive on lore.kernel.org
 help / color / Atom feed
From: Wei Wang <tracywwnj@gmail.com>
To: David Miller <davem@davemloft.net>, netdev@vger.kernel.org
Cc: Martin KaFai Lau <kafai@fb.com>,
	Eric Dumazet <edumazet@google.com>,
	Mahesh Bandewar <maheshb@google.com>,
	David Ahern <dsahern@gmail.com>, Wei Wang <weiwan@google.com>
Subject: [PATCH net-next 4/5] ipv6: convert rx data path to not take refcnt on dst
Date: Tue, 18 Jun 2019 11:25:42 -0700
Message-ID: <20190618182543.65477-5-tracywwnj@gmail.com> (raw)
In-Reply-To: <20190618182543.65477-1-tracywwnj@gmail.com>

From: Wei Wang <weiwan@google.com>

ip6_route_input() is the key function to do the route lookup in the
rx data path. All the callers to this function are already holding rcu
lock. So it is fairly easy to convert it to not take refcnt on the dst:
We pass in flag RT6_LOOKUP_F_DST_NOREF and do skb_dst_set_noref().
This saves a few atomic inc or dec operations and should boost
performance overall.
This also makes the logic more aligned with v4.

Signed-off-by: Wei Wang <weiwan@google.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Acked-by: Mahesh Bandewar <maheshb@google.com>
---
 net/ipv6/route.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 33dc8af9a4bf..d2b287635aab 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -2375,11 +2375,12 @@ u32 rt6_multipath_hash(const struct net *net, const struct flowi6 *fl6,
 	return mhash >> 1;
 }
 
+/* Called with rcu held */
 void ip6_route_input(struct sk_buff *skb)
 {
 	const struct ipv6hdr *iph = ipv6_hdr(skb);
 	struct net *net = dev_net(skb->dev);
-	int flags = RT6_LOOKUP_F_HAS_SADDR;
+	int flags = RT6_LOOKUP_F_HAS_SADDR | RT6_LOOKUP_F_DST_NOREF;
 	struct ip_tunnel_info *tun_info;
 	struct flowi6 fl6 = {
 		.flowi6_iif = skb->dev->ifindex,
@@ -2401,8 +2402,8 @@ void ip6_route_input(struct sk_buff *skb)
 	if (unlikely(fl6.flowi6_proto == IPPROTO_ICMPV6))
 		fl6.mp_hash = rt6_multipath_hash(net, &fl6, skb, flkeys);
 	skb_dst_drop(skb);
-	skb_dst_set(skb,
-		    ip6_route_input_lookup(net, skb->dev, &fl6, skb, flags));
+	skb_dst_set_noref(skb, ip6_route_input_lookup(net, skb->dev,
+						      &fl6, skb, flags));
 }
 
 static struct rt6_info *ip6_pol_route_output(struct net *net,
-- 
2.22.0.410.gd8fdbe21b5-goog


  parent reply index

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-06-18 18:25 [PATCH net-next 0/5] ipv6: avoid taking refcnt on dst during route lookup Wei Wang
2019-06-18 18:25 ` [PATCH net-next 1/5] ipv6: introduce RT6_LOOKUP_F_DST_NOREF flag in ip6_pol_route() Wei Wang
2019-06-18 18:25 ` [PATCH net-next 2/5] ipv6: initialize rt6->rt6i_uncached in all pre-allocated dst entries Wei Wang
2019-06-18 18:25 ` [PATCH net-next 3/5] ipv6: honor RT6_LOOKUP_F_DST_NOREF in rule lookup logic Wei Wang
2019-06-19 16:07   ` David Miller
2019-06-19 16:51     ` Wei Wang
2019-06-18 18:25 ` Wei Wang [this message]
2019-06-18 18:25 ` [PATCH net-next 5/5] ipv6: convert major tx path to use RT6_LOOKUP_F_DST_NOREF Wei Wang
2019-06-20 22:47   ` kbuild test robot

Reply instructions:

You may reply publically to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20190618182543.65477-5-tracywwnj@gmail.com \
    --to=tracywwnj@gmail.com \
    --cc=davem@davemloft.net \
    --cc=dsahern@gmail.com \
    --cc=edumazet@google.com \
    --cc=kafai@fb.com \
    --cc=maheshb@google.com \
    --cc=netdev@vger.kernel.org \
    --cc=weiwan@google.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Netdev Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/netdev/0 netdev/git/0.git
	git clone --mirror https://lore.kernel.org/netdev/1 netdev/git/1.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 netdev netdev/ https://lore.kernel.org/netdev \
		netdev@vger.kernel.org netdev@archiver.kernel.org
	public-inbox-index netdev


Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.netdev


AGPL code for this site: git clone https://public-inbox.org/ public-inbox