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Message-Id: <20190319140108.195288-1-edumazet@google.com>
Date: Tue, 19 Mar 2019 07:01:08 -0700
From: Eric Dumazet <edumazet@...gle.com>
To: "David S . Miller" <davem@...emloft.net>
Cc: netdev <netdev@...r.kernel.org>,
Eric Dumazet <edumazet@...gle.com>,
Eric Dumazet <eric.dumazet@...il.com>
Subject: [PATCH net-next] tcp: add tcp_inet6_sk() helper
TCP ipv6 fast path dereferences a pointer to get to the inet6
part of a tcp socket, but given the fixed memory placement,
we can do better and avoid a possible cache line miss.
This also reduces register pressure, since we let the compiler
know about this memory placement.
Signed-off-by: Eric Dumazet <edumazet@...gle.com>
---
net/ipv6/tcp_ipv6.c | 44 ++++++++++++++++++++++++++------------------
1 file changed, 26 insertions(+), 18 deletions(-)
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 57ef69a1088908fc624ecfca99a728fa296ae0bf..983ad7a751027cb8fbaee095b90225d71fbaa698 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -90,6 +90,17 @@ static struct tcp_md5sig_key *tcp_v6_md5_do_lookup(const struct sock *sk,
}
#endif
+/* Helper returning the inet6 address from a given tcp socket.
+ * It can be used in TCP stack instead of inet6_sk(sk).
+ * This avoids a dereference and allow compiler optimizations.
+ */
+static struct ipv6_pinfo *tcp_inet6_sk(const struct sock *sk)
+{
+ struct tcp6_sock *tcp6 = container_of(tcp_sk(sk), struct tcp6_sock, tcp);
+
+ return &tcp6->inet6;
+}
+
static void inet6_sk_rx_dst_set(struct sock *sk, const struct sk_buff *skb)
{
struct dst_entry *dst = skb_dst(skb);
@@ -99,7 +110,7 @@ static void inet6_sk_rx_dst_set(struct sock *sk, const struct sk_buff *skb)
sk->sk_rx_dst = dst;
inet_sk(sk)->rx_dst_ifindex = skb->skb_iif;
- inet6_sk(sk)->rx_dst_cookie = rt6_get_cookie(rt);
+ tcp_inet6_sk(sk)->rx_dst_cookie = rt6_get_cookie(rt);
}
}
@@ -138,7 +149,7 @@ static int tcp_v6_connect(struct sock *sk, struct sockaddr *uaddr,
struct sockaddr_in6 *usin = (struct sockaddr_in6 *) uaddr;
struct inet_sock *inet = inet_sk(sk);
struct inet_connection_sock *icsk = inet_csk(sk);
- struct ipv6_pinfo *np = inet6_sk(sk);
+ struct ipv6_pinfo *np = tcp_inet6_sk(sk);
struct tcp_sock *tp = tcp_sk(sk);
struct in6_addr *saddr = NULL, *final_p, final;
struct ipv6_txoptions *opt;
@@ -390,7 +401,7 @@ static int tcp_v6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
if (sk->sk_state == TCP_CLOSE)
goto out;
- if (ipv6_hdr(skb)->hop_limit < inet6_sk(sk)->min_hopcount) {
+ if (ipv6_hdr(skb)->hop_limit < tcp_inet6_sk(sk)->min_hopcount) {
__NET_INC_STATS(net, LINUX_MIB_TCPMINTTLDROP);
goto out;
}
@@ -405,7 +416,7 @@ static int tcp_v6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
goto out;
}
- np = inet6_sk(sk);
+ np = tcp_inet6_sk(sk);
if (type == NDISC_REDIRECT) {
if (!sock_owned_by_user(sk)) {
@@ -478,7 +489,7 @@ static int tcp_v6_send_synack(const struct sock *sk, struct dst_entry *dst,
enum tcp_synack_type synack_type)
{
struct inet_request_sock *ireq = inet_rsk(req);
- struct ipv6_pinfo *np = inet6_sk(sk);
+ struct ipv6_pinfo *np = tcp_inet6_sk(sk);
struct ipv6_txoptions *opt;
struct flowi6 *fl6 = &fl->u.ip6;
struct sk_buff *skb;
@@ -737,7 +748,7 @@ static void tcp_v6_init_req(struct request_sock *req,
{
bool l3_slave = ipv6_l3mdev_skb(TCP_SKB_CB(skb)->header.h6.flags);
struct inet_request_sock *ireq = inet_rsk(req);
- const struct ipv6_pinfo *np = inet6_sk(sk_listener);
+ const struct ipv6_pinfo *np = tcp_inet6_sk(sk_listener);
ireq->ir_v6_rmt_addr = ipv6_hdr(skb)->saddr;
ireq->ir_v6_loc_addr = ipv6_hdr(skb)->daddr;
@@ -1066,9 +1077,8 @@ static struct sock *tcp_v6_syn_recv_sock(const struct sock *sk, struct sk_buff *
{
struct inet_request_sock *ireq;
struct ipv6_pinfo *newnp;
- const struct ipv6_pinfo *np = inet6_sk(sk);
+ const struct ipv6_pinfo *np = tcp_inet6_sk(sk);
struct ipv6_txoptions *opt;
- struct tcp6_sock *newtcp6sk;
struct inet_sock *newinet;
struct tcp_sock *newtp;
struct sock *newsk;
@@ -1088,11 +1098,10 @@ static struct sock *tcp_v6_syn_recv_sock(const struct sock *sk, struct sk_buff *
if (!newsk)
return NULL;
- newtcp6sk = (struct tcp6_sock *)newsk;
- inet_sk(newsk)->pinet6 = &newtcp6sk->inet6;
+ inet_sk(newsk)->pinet6 = tcp_inet6_sk(newsk);
newinet = inet_sk(newsk);
- newnp = inet6_sk(newsk);
+ newnp = tcp_inet6_sk(newsk);
newtp = tcp_sk(newsk);
memcpy(newnp, np, sizeof(struct ipv6_pinfo));
@@ -1156,12 +1165,11 @@ static struct sock *tcp_v6_syn_recv_sock(const struct sock *sk, struct sk_buff *
ip6_dst_store(newsk, dst, NULL, NULL);
inet6_sk_rx_dst_set(newsk, skb);
- newtcp6sk = (struct tcp6_sock *)newsk;
- inet_sk(newsk)->pinet6 = &newtcp6sk->inet6;
+ inet_sk(newsk)->pinet6 = tcp_inet6_sk(newsk);
newtp = tcp_sk(newsk);
newinet = inet_sk(newsk);
- newnp = inet6_sk(newsk);
+ newnp = tcp_inet6_sk(newsk);
memcpy(newnp, np, sizeof(struct ipv6_pinfo));
@@ -1276,9 +1284,9 @@ static struct sock *tcp_v6_syn_recv_sock(const struct sock *sk, struct sk_buff *
*/
static int tcp_v6_do_rcv(struct sock *sk, struct sk_buff *skb)
{
- struct ipv6_pinfo *np = inet6_sk(sk);
- struct tcp_sock *tp;
+ struct ipv6_pinfo *np = tcp_inet6_sk(sk);
struct sk_buff *opt_skb = NULL;
+ struct tcp_sock *tp;
/* Imagine: socket is IPv6. IPv4 packet arrives,
goes to IPv4 receive handler and backlogged.
@@ -1524,7 +1532,7 @@ static int tcp_v6_rcv(struct sk_buff *skb)
return 0;
}
}
- if (hdr->hop_limit < inet6_sk(sk)->min_hopcount) {
+ if (hdr->hop_limit < tcp_inet6_sk(sk)->min_hopcount) {
__NET_INC_STATS(net, LINUX_MIB_TCPMINTTLDROP);
goto discard_and_relse;
}
@@ -1669,7 +1677,7 @@ static void tcp_v6_early_demux(struct sk_buff *skb)
struct dst_entry *dst = READ_ONCE(sk->sk_rx_dst);
if (dst)
- dst = dst_check(dst, inet6_sk(sk)->rx_dst_cookie);
+ dst = dst_check(dst, tcp_inet6_sk(sk)->rx_dst_cookie);
if (dst &&
inet_sk(sk)->rx_dst_ifindex == skb->skb_iif)
skb_dst_set_noref(skb, dst);
--
2.21.0.225.g810b269d1ac-goog
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