1 files changed, 35 insertions, 21 deletions

diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 44d431849d39..eec814fe53b8 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 @@ out:
  */
 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.
@@ -1428,6 +1436,7 @@ static void tcp_v6_fill_cb(struct sk_buff *skb, const struct ipv6hdr *hdr,
 
 static int tcp_v6_rcv(struct sk_buff *skb)
 {
+        struct sk_buff *skb_to_free;
         int sdif = inet6_sdif(skb);
         const struct tcphdr *th;
         const struct ipv6hdr *hdr;
@@ -1524,7 +1533,7 @@ process:
                         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;
         }
@@ -1554,12 +1563,17 @@ process:
         tcp_segs_in(tcp_sk(sk), skb);
         ret = 0;
         if (!sock_owned_by_user(sk)) {
+                skb_to_free = sk->sk_rx_skb_cache;
+                sk->sk_rx_skb_cache = NULL;
                 ret = tcp_v6_do_rcv(sk, skb);
-        } else if (tcp_add_backlog(sk, skb)) {
-                goto discard_and_relse;
+        } else {
+                if (tcp_add_backlog(sk, skb))
+                        goto discard_and_relse;
+                skb_to_free = NULL;
         }
         bh_unlock_sock(sk);
-
+        if (skb_to_free)
+                __kfree_skb(skb_to_free);
 put_and_return:
         if (refcounted)
                 sock_put(sk);
@@ -1669,7 +1683,7 @@ 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);