[DECNET]: Tidy send side socket SKB allocation.

Patch from Steve Whitehouse which I've vetted and tested:

"This patch is really intended has a move towards fixing the
sendmsg/recvmsg functions in various ways so that we will finally
have working nagle. Also reduces code duplication."

Signed-off-by: Patrick Caulfield <patrick@tykepenguin.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 33 insertions, 7 deletions

diff --git a/net/decnet/af_decnet.c b/net/decnet/af_decnet.c
index 621680f127af..348f36b529f7 100644
--- a/net/decnet/af_decnet.c
+++ b/net/decnet/af_decnet.c
@@ -1876,8 +1876,27 @@ static inline unsigned int dn_current_mss(struct sock *sk, int flags)
         return mss_now;
 }
 
+/* 
+ * N.B. We get the timeout wrong here, but then we always did get it
+ * wrong before and this is another step along the road to correcting
+ * it. It ought to get updated each time we pass through the routine,
+ * but in practise it probably doesn't matter too much for now.
+ */
+static inline struct sk_buff *dn_alloc_send_pskb(struct sock *sk,
+                              unsigned long datalen, int noblock,
+                              int *errcode)
+{
+        struct sk_buff *skb = sock_alloc_send_skb(sk, datalen,
+                                                   noblock, errcode);
+        if (skb) {
+                skb->protocol = __constant_htons(ETH_P_DNA_RT);
+                skb->pkt_type = PACKET_OUTGOING;
+        }
+        return skb;
+}
+
 static int dn_sendmsg(struct kiocb *iocb, struct socket *sock,
-           struct msghdr *msg, size_t size)
+                      struct msghdr *msg, size_t size)
 {
         struct sock *sk = sock->sk;
         struct dn_scp *scp = DN_SK(sk);
@@ -1892,7 +1911,7 @@ static int dn_sendmsg(struct kiocb *iocb, struct socket *sock,
         struct dn_skb_cb *cb;
         size_t len;
         unsigned char fctype;
-        long timeo = sock_sndtimeo(sk, flags & MSG_DONTWAIT);
+        long timeo;
 
         if (flags & ~(MSG_TRYHARD|MSG_OOB|MSG_DONTWAIT|MSG_EOR|MSG_NOSIGNAL|MSG_MORE|MSG_CMSG_COMPAT))
                 return -EOPNOTSUPP;
@@ -1900,18 +1919,21 @@ static int dn_sendmsg(struct kiocb *iocb, struct socket *sock,
         if (addr_len && (addr_len != sizeof(struct sockaddr_dn)))
                 return -EINVAL;
 
+        lock_sock(sk);
+        timeo = sock_sndtimeo(sk, flags & MSG_DONTWAIT);
         /*
          * The only difference between stream sockets and sequenced packet
          * sockets is that the stream sockets always behave as if MSG_EOR
          * has been set.
          */
         if (sock->type == SOCK_STREAM) {
-                if (flags & MSG_EOR)
-                        return -EINVAL;
+                if (flags & MSG_EOR) {
+                        err = -EINVAL;
+                        goto out;
+                }
                 flags |= MSG_EOR;
         }
 
-        lock_sock(sk);
 
         err = dn_check_state(sk, addr, addr_len, &timeo, flags);
         if (err)
@@ -1980,8 +2002,12 @@ static int dn_sendmsg(struct kiocb *iocb, struct socket *sock,
 
                 /*
                  * Get a suitably sized skb.
+                 * 64 is a bit of a hack really, but its larger than any
+                 * link-layer headers and has served us well as a good
+                 * guess as to their real length.
                  */
-                skb = dn_alloc_send_skb(sk, &len, flags & MSG_DONTWAIT, timeo, &err);
+                skb = dn_alloc_send_pskb(sk, len + 64 + DN_MAX_NSP_DATA_HEADER,
+                                         flags & MSG_DONTWAIT, &err);
 
                 if (err)
                         break;
@@ -1991,7 +2017,7 @@ static int dn_sendmsg(struct kiocb *iocb, struct socket *sock,
 
                 cb = DN_SKB_CB(skb);
 
-                skb_reserve(skb, DN_MAX_NSP_DATA_HEADER);
+                skb_reserve(skb, 64 + DN_MAX_NSP_DATA_HEADER);
 
                 if (memcpy_fromiovec(skb_put(skb, len), msg->msg_iov, len)) {
                         err = -EFAULT;