inet: Decrease overhead of on-stack inet_cork.

When we fast path datagram sends to avoid locking by putting
the inet_cork on the stack we use up lots of space that isn't
necessary.

This is because inet_cork contains a "struct flowi" which isn't
used in these code paths.

Split inet_cork to two parts, "inet_cork" and "inet_cork_full".
Only the latter of which has the "struct flowi" and is what is
stored in inet_sock.

Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Eric Dumazet <eric.dumazet@gmail.com>

2 files changed, 20 insertions, 18 deletions

diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index 4cfbb24b9e04..9d4b165837d6 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -1150,6 +1150,7 @@ int ip6_append_data(struct sock *sk, int getfrag(void *from, char *to,
 {
         struct inet_sock *inet = inet_sk(sk);
         struct ipv6_pinfo *np = inet6_sk(sk);
+        struct inet_cork *cork;
         struct sk_buff *skb;
         unsigned int maxfraglen, fragheaderlen;
         int exthdrlen;
@@ -1163,6 +1164,7 @@ int ip6_append_data(struct sock *sk, int getfrag(void *from, char *to,
 
         if (flags&MSG_PROBE)
                 return 0;
+        cork = &inet->cork.base;
         if (skb_queue_empty(&sk->sk_write_queue)) {
                 /*
                  * setup for corking
@@ -1202,7 +1204,7 @@ int ip6_append_data(struct sock *sk, int getfrag(void *from, char *to,
                         /* need source address above miyazawa*/
                 }
                 dst_hold(&rt->dst);
-                inet->cork.dst = &rt->dst;
+                cork->dst = &rt->dst;
                 inet->cork.fl.u.ip6 = *fl6;
                 np->cork.hop_limit = hlimit;
                 np->cork.tclass = tclass;
@@ -1212,10 +1214,10 @@ int ip6_append_data(struct sock *sk, int getfrag(void *from, char *to,
                         if (np->frag_size)
                                 mtu = np->frag_size;
                 }
-                inet->cork.fragsize = mtu;
+                cork->fragsize = mtu;
                 if (dst_allfrag(rt->dst.path))
-                        inet->cork.flags |= IPCORK_ALLFRAG;
-                inet->cork.length = 0;
+                        cork->flags |= IPCORK_ALLFRAG;
+                cork->length = 0;
                 sk->sk_sndmsg_page = NULL;
                 sk->sk_sndmsg_off = 0;
                 exthdrlen = rt->dst.header_len + (opt ? opt->opt_flen : 0) -
@@ -1223,12 +1225,12 @@ int ip6_append_data(struct sock *sk, int getfrag(void *from, char *to,
                 length += exthdrlen;
                 transhdrlen += exthdrlen;
         } else {
-                rt = (struct rt6_info *)inet->cork.dst;
+                rt = (struct rt6_info *)cork->dst;
                 fl6 = &inet->cork.fl.u.ip6;
                 opt = np->cork.opt;
                 transhdrlen = 0;
                 exthdrlen = 0;
-                mtu = inet->cork.fragsize;
+                mtu = cork->fragsize;
         }
 
         hh_len = LL_RESERVED_SPACE(rt->dst.dev);
@@ -1238,7 +1240,7 @@ int ip6_append_data(struct sock *sk, int getfrag(void *from, char *to,
         maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen - sizeof(struct frag_hdr);
 
         if (mtu <= sizeof(struct ipv6hdr) + IPV6_MAXPLEN) {
-                if (inet->cork.length + length > sizeof(struct ipv6hdr) + IPV6_MAXPLEN - fragheaderlen) {
+                if (cork->length + length > sizeof(struct ipv6hdr) + IPV6_MAXPLEN - fragheaderlen) {
                         ipv6_local_error(sk, EMSGSIZE, fl6, mtu-exthdrlen);
                         return -EMSGSIZE;
                 }
@@ -1267,7 +1269,7 @@ int ip6_append_data(struct sock *sk, int getfrag(void *from, char *to,
          * --yoshfuji
          */
 
-        inet->cork.length += length;
+        cork->length += length;
         if (length > mtu) {
                 int proto = sk->sk_protocol;
                 if (dontfrag && (proto == IPPROTO_UDP || proto == IPPROTO_RAW)){
@@ -1292,7 +1294,7 @@ int ip6_append_data(struct sock *sk, int getfrag(void *from, char *to,
 
         while (length > 0) {
                 /* Check if the remaining data fits into current packet. */
-                copy = (inet->cork.length <= mtu && !(inet->cork.flags & IPCORK_ALLFRAG) ? mtu : maxfraglen) - skb->len;
+                copy = (cork->length <= mtu && !(cork->flags & IPCORK_ALLFRAG) ? mtu : maxfraglen) - skb->len;
                 if (copy < length)
                         copy = maxfraglen - skb->len;
 
@@ -1317,7 +1319,7 @@ alloc_new_skb:
                          * we know we need more fragment(s).
                          */
                         datalen = length + fraggap;
-                        if (datalen > (inet->cork.length <= mtu && !(inet->cork.flags & IPCORK_ALLFRAG) ? mtu : maxfraglen) - fragheaderlen)
+                        if (datalen > (cork->length <= mtu && !(cork->flags & IPCORK_ALLFRAG) ? mtu : maxfraglen) - fragheaderlen)
                                 datalen = maxfraglen - fragheaderlen;
 
                         fraglen = datalen + fragheaderlen;
@@ -1481,7 +1483,7 @@ alloc_new_skb:
         }
         return 0;
 error:
-        inet->cork.length -= length;
+        cork->length -= length;
         IP6_INC_STATS(sock_net(sk), rt->rt6i_idev, IPSTATS_MIB_OUTDISCARDS);
         return err;
 }
@@ -1497,10 +1499,10 @@ static void ip6_cork_release(struct inet_sock *inet, struct ipv6_pinfo *np)
                 np->cork.opt = NULL;
         }
 
-        if (inet->cork.dst) {
-                dst_release(inet->cork.dst);
-                inet->cork.dst = NULL;
-                inet->cork.flags &= ~IPCORK_ALLFRAG;
+        if (inet->cork.base.dst) {
+                dst_release(inet->cork.base.dst);
+                inet->cork.base.dst = NULL;
+                inet->cork.base.flags &= ~IPCORK_ALLFRAG;
         }
         memset(&inet->cork.fl, 0, sizeof(inet->cork.fl));
 }
@@ -1515,7 +1517,7 @@ int ip6_push_pending_frames(struct sock *sk)
         struct net *net = sock_net(sk);
         struct ipv6hdr *hdr;
         struct ipv6_txoptions *opt = np->cork.opt;
-        struct rt6_info *rt = (struct rt6_info *)inet->cork.dst;
+        struct rt6_info *rt = (struct rt6_info *)inet->cork.base.dst;
         struct flowi6 *fl6 = &inet->cork.fl.u.ip6;
         unsigned char proto = fl6->flowi6_proto;
         int err = 0;
diff --git a/net/ipv6/raw.c b/net/ipv6/raw.c
index e5e5425fe7d0..ae64984f81aa 100644
--- a/net/ipv6/raw.c
+++ b/net/ipv6/raw.c
@@ -542,8 +542,8 @@ static int rawv6_push_pending_frames(struct sock *sk, struct flowi6 *fl6,
                 goto out;
 
         offset = rp->offset;
-        total_len = inet_sk(sk)->cork.length - (skb_network_header(skb) -
-                                                skb->data);
+        total_len = inet_sk(sk)->cork.base.length - (skb_network_header(skb) -
+                                                     skb->data);
         if (offset >= total_len - 1) {
                 err = -EINVAL;
                 ip6_flush_pending_frames(sk);