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>

1 files changed, 18 insertions, 16 deletions

diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index 4cfbb24..9d4b165 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;