ipv6: introduce ipv6_make_skb

This commit is very similar to
commit 1c32c5ad6fac8cee1a77449f5abf211e911ff830
Author: Herbert Xu <herbert@gondor.apana.org.au>
Date:   Tue Mar 1 02:36:47 2011 +0000

    inet: Add ip_make_skb and ip_finish_skb

It adds IPv6 version of the helpers ip6_make_skb and ip6_finish_skb.

The job of ip6_make_skb is to collect messages into an ipv6 packet
and poplulate ipv6 eader.  The job of ip6_finish_skb is to transmit
the generated skb.  Together they replicated the job of
ip6_push_pending_frames() while also provide the capability to be
called independently.  This will be needed to add lockless UDP sendmsg
support.

Signed-off-by: Vladislav Yasevich <vyasevic@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 84 insertions, 19 deletions

diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index 1b66453a695d..b89d3c27dac7 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -1564,22 +1564,23 @@ static void ip6_cork_release(struct inet_cork_full *cork,
         memset(&cork->fl, 0, sizeof(cork->fl));
 }
 
-int ip6_push_pending_frames(struct sock *sk)
+struct sk_buff *__ip6_make_skb(struct sock *sk,
+                               struct sk_buff_head *queue,
+                               struct inet_cork_full *cork,
+                               struct inet6_cork *v6_cork)
 {
         struct sk_buff *skb, *tmp_skb;
         struct sk_buff **tail_skb;
         struct in6_addr final_dst_buf, *final_dst = &final_dst_buf;
-        struct inet_sock *inet = inet_sk(sk);
         struct ipv6_pinfo *np = inet6_sk(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.base.dst;
-        struct flowi6 *fl6 = &inet->cork.fl.u.ip6;
+        struct ipv6_txoptions *opt = v6_cork->opt;
+        struct rt6_info *rt = (struct rt6_info *)cork->base.dst;
+        struct flowi6 *fl6 = &cork->fl.u.ip6;
         unsigned char proto = fl6->flowi6_proto;
-        int err = 0;
 
-        skb = __skb_dequeue(&sk->sk_write_queue);
+        skb = __skb_dequeue(queue);
         if (skb == NULL)
                 goto out;
         tail_skb = &(skb_shinfo(skb)->frag_list);
@@ -1587,7 +1588,7 @@ int ip6_push_pending_frames(struct sock *sk)
         /* move skb->data to ip header from ext header */
         if (skb->data < skb_network_header(skb))
                 __skb_pull(skb, skb_network_offset(skb));
-        while ((tmp_skb = __skb_dequeue(&sk->sk_write_queue)) != NULL) {
+        while ((tmp_skb = __skb_dequeue(queue)) != NULL) {
                 __skb_pull(tmp_skb, skb_network_header_len(skb));
                 *tail_skb = tmp_skb;
                 tail_skb = &(tmp_skb->next);
@@ -1612,10 +1613,10 @@ int ip6_push_pending_frames(struct sock *sk)
         skb_reset_network_header(skb);
         hdr = ipv6_hdr(skb);
 
-        ip6_flow_hdr(hdr, np->cork.tclass,
+        ip6_flow_hdr(hdr, v6_cork->tclass,
                      ip6_make_flowlabel(net, skb, fl6->flowlabel,
                                         np->autoflowlabel));
-        hdr->hop_limit = np->cork.hop_limit;
+        hdr->hop_limit = v6_cork->hop_limit;
         hdr->nexthdr = proto;
         hdr->saddr = fl6->saddr;
         hdr->daddr = *final_dst;
@@ -1632,25 +1633,45 @@ int ip6_push_pending_frames(struct sock *sk)
                 ICMP6_INC_STATS(net, idev, ICMP6_MIB_OUTMSGS);
         }
 
+        ip6_cork_release(cork, v6_cork);
+out:
+        return skb;
+}
+
+int ip6_send_skb(struct sk_buff *skb)
+{
+        struct net *net = sock_net(skb->sk);
+        struct rt6_info *rt = (struct rt6_info *)skb_dst(skb);
+        int err;
+
         err = ip6_local_out(skb);
         if (err) {
                 if (err > 0)
                         err = net_xmit_errno(err);
                 if (err)
-                        goto error;
+                        IP6_INC_STATS(net, rt->rt6i_idev,
+                                      IPSTATS_MIB_OUTDISCARDS);
         }
 
-out:
-        ip6_cork_release(&inet->cork, &np->cork);
         return err;
-error:
-        IP6_INC_STATS(net, rt->rt6i_idev, IPSTATS_MIB_OUTDISCARDS);
-        goto out;
+}
+
+int ip6_push_pending_frames(struct sock *sk)
+{
+        struct sk_buff *skb;
+
+        skb = ip6_finish_skb(sk);
+        if (!skb)
+                return 0;
+
+        return ip6_send_skb(skb);
 }
 EXPORT_SYMBOL_GPL(ip6_push_pending_frames);
 
 static void __ip6_flush_pending_frames(struct sock *sk,
-                                       struct sk_buff_head *queue)
+                                       struct sk_buff_head *queue,
+                                       struct inet_cork_full *cork,
+                                       struct inet6_cork *v6_cork)
 {
         struct sk_buff *skb;
 
@@ -1661,11 +1682,55 @@ static void __ip6_flush_pending_frames(struct sock *sk,
                 kfree_skb(skb);
         }
 
-        ip6_cork_release(&inet_sk(sk)->cork, &inet6_sk(sk)->cork);
+        ip6_cork_release(cork, v6_cork);
 }
 
 void ip6_flush_pending_frames(struct sock *sk)
 {
-        __ip6_flush_pending_frames(sk, &sk->sk_write_queue);
+        __ip6_flush_pending_frames(sk, &sk->sk_write_queue,
+                                   &inet_sk(sk)->cork, &inet6_sk(sk)->cork);
 }
 EXPORT_SYMBOL_GPL(ip6_flush_pending_frames);
+
+struct sk_buff *ip6_make_skb(struct sock *sk,
+                             int getfrag(void *from, char *to, int offset,
+                                         int len, int odd, struct sk_buff *skb),
+                             void *from, int length, int transhdrlen,
+                             int hlimit, int tclass,
+                             struct ipv6_txoptions *opt, struct flowi6 *fl6,
+                             struct rt6_info *rt, unsigned int flags,
+                             int dontfrag)
+{
+        struct inet_cork_full cork;
+        struct inet6_cork v6_cork;
+        struct sk_buff_head queue;
+        int exthdrlen = (opt ? opt->opt_flen : 0);
+        int err;
+
+        if (flags & MSG_PROBE)
+                return NULL;
+
+        __skb_queue_head_init(&queue);
+
+        cork.base.flags = 0;
+        cork.base.addr = 0;
+        cork.base.opt = NULL;
+        v6_cork.opt = NULL;
+        err = ip6_setup_cork(sk, &cork, &v6_cork, hlimit, tclass, opt, rt, fl6);
+        if (err)
+                return ERR_PTR(err);
+
+        if (dontfrag < 0)
+                dontfrag = inet6_sk(sk)->dontfrag;
+
+        err = __ip6_append_data(sk, fl6, &queue, &cork.base, &v6_cork,
+                                &current->task_frag, getfrag, from,
+                                length + exthdrlen, transhdrlen + exthdrlen,
+                                flags, dontfrag);
+        if (err) {
+                __ip6_flush_pending_frames(sk, &queue, &cork, &v6_cork);
+                return ERR_PTR(err);
+        }
+
+        return __ip6_make_skb(sk, &queue, &cork, &v6_cork);
+}