[TCP/DCCP]: Introduce net_xmit_eval

Throughout the TCP/DCCP (and tunnelling) code, it often happens that the
return code of a transmit function needs to be tested against NET_XMIT_CN
which is a value that does not indicate a strict error condition.

This patch uses a macro for these recurring situations which is consistent
with the already existing macro net_xmit_errno, saving on duplicated code.

Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>

9 files changed, 14 insertions, 30 deletions

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 4e967b2e22cc..caa3c2593719 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -66,6 +66,10 @@ struct netpoll_info;
 #define NET_RX_CN_HIGH          4   /* The storm is here */
 #define NET_RX_BAD              5  /* packet dropped due to kernel error */
 
+/* NET_XMIT_CN is special. It does not guarantee that this packet is lost. It
+ * indicates that the device will soon be dropping packets, or already drops
+ * some packets of the same priority; prompting us to send less aggressively. */
+#define net_xmit_eval(e)        ((e) == NET_XMIT_CN? 0 : (e))
 #define net_xmit_errno(e)       ((e) != NET_XMIT_CN ? -ENOBUFS : 0)
 
 #endif
diff --git a/include/net/ipip.h b/include/net/ipip.h
index f490c3cbe377..84058858eea7 100644
--- a/include/net/ipip.h
+++ b/include/net/ipip.h
@@ -35,7 +35,7 @@ struct ip_tunnel
         ip_send_check(iph);                                             \
                                                                         \
         err = NF_HOOK(PF_INET, NF_IP_LOCAL_OUT, skb, NULL, rt->u.dst.dev, dst_output);\
-        if (err == NET_XMIT_SUCCESS || err == NET_XMIT_CN) {            \
+        if (net_xmit_eval(err) == 0) {                                  \
                 stats->tx_bytes += pkt_len;                             \
                 stats->tx_packets++;                                    \
         } else {                                                        \
diff --git a/net/dccp/ipv4.c b/net/dccp/ipv4.c
index bc400b2ba25e..61c09014dade 100644
--- a/net/dccp/ipv4.c
+++ b/net/dccp/ipv4.c
@@ -501,8 +501,7 @@ static int dccp_v4_send_response(struct sock *sk, struct request_sock *req,
                 err = ip_build_and_send_pkt(skb, sk, ireq->loc_addr,
                                             ireq->rmt_addr,
                                             ireq->opt);
-                if (err == NET_XMIT_CN)
-                        err = 0;
+                err = net_xmit_eval(err);
         }
 
 out:
@@ -571,7 +570,7 @@ static void dccp_v4_ctl_send_reset(struct sk_buff *rxskb)
                                     rxskb->nh.iph->saddr, NULL);
         bh_unlock_sock(dccp_v4_ctl_socket->sk);
 
-        if (err == NET_XMIT_CN || err == 0) {
+        if (net_xmit_eval(err) == 0) {
                 DCCP_INC_STATS_BH(DCCP_MIB_OUTSEGS);
                 DCCP_INC_STATS_BH(DCCP_MIB_OUTRSTS);
         }
diff --git a/net/dccp/ipv6.c b/net/dccp/ipv6.c
index 8d6ddb6389a7..2165b1740c7c 100644
--- a/net/dccp/ipv6.c
+++ b/net/dccp/ipv6.c
@@ -294,8 +294,7 @@ static int dccp_v6_send_response(struct sock *sk, struct request_sock *req,
                                                          &ireq6->rmt_addr);
                 ipv6_addr_copy(&fl.fl6_dst, &ireq6->rmt_addr);
                 err = ip6_xmit(sk, skb, &fl, opt, 0);
-                if (err == NET_XMIT_CN)
-                        err = 0;
+                err = net_xmit_eval(err);
         }
 
 done:
diff --git a/net/dccp/output.c b/net/dccp/output.c
index 0994b13f0f15..ef22f3cc791a 100644
--- a/net/dccp/output.c
+++ b/net/dccp/output.c
@@ -125,16 +125,7 @@ static int dccp_transmit_skb(struct sock *sk, struct sk_buff *skb)
 
                 memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
                 err = icsk->icsk_af_ops->queue_xmit(skb, sk, 0);
-                if (err <= 0)
-                        return err;
-
-                /* NET_XMIT_CN is special. It does not guarantee,
-                 * that this packet is lost. It tells that device
-                 * is about to start to drop packets or already
-                 * drops some packets of the same priority and
-                 * invokes us to send less aggressively.
-                 */
-                return err == NET_XMIT_CN ? 0 : err;
+                return net_xmit_eval(err);
         }
         return -ENOBUFS;
 }
@@ -426,8 +417,7 @@ int dccp_send_reset(struct sock *sk, enum dccp_reset_codes code)
                 if (skb != NULL) {
                         memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
                         err = inet_csk(sk)->icsk_af_ops->queue_xmit(skb, sk, 0);
-                        if (err == NET_XMIT_CN)
-                                err = 0;
+                        return net_xmit_eval(err);
                 }
         }
 
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 2eb58844403c..0ad0904bf56c 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -662,8 +662,7 @@ static int tcp_v4_send_synack(struct sock *sk, struct request_sock *req,
                 err = ip_build_and_send_pkt(skb, sk, ireq->loc_addr,
                                             ireq->rmt_addr,
                                             ireq->opt);
-                if (err == NET_XMIT_CN)
-                        err = 0;
+                err = net_xmit_eval(err);
         }
 
 out:
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index f63e99aac2d5..6a8581ab9a23 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -484,13 +484,7 @@ static int tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, int clone_it,
 
         tcp_enter_cwr(sk);
 
-        /* NET_XMIT_CN is special. It does not guarantee,
-         * that this packet is lost. It tells that device
-         * is about to start to drop packets or already
-         * drops some packets of the same priority and
-         * invokes us to send less aggressively.
-         */
-        return err == NET_XMIT_CN ? 0 : err;
+        return net_xmit_eval(err);
 
 #undef SYSCTL_FLAG_TSTAMPS
 #undef SYSCTL_FLAG_WSCALE
diff --git a/net/ipv6/ip6_tunnel.c b/net/ipv6/ip6_tunnel.c
index 4919f9294e2a..80a11909159d 100644
--- a/net/ipv6/ip6_tunnel.c
+++ b/net/ipv6/ip6_tunnel.c
@@ -748,7 +748,7 @@ ip6ip6_tnl_xmit(struct sk_buff *skb, struct net_device *dev)
         err = NF_HOOK(PF_INET6, NF_IP6_LOCAL_OUT, skb, NULL, 
                       skb->dst->dev, dst_output);
 
-        if (err == NET_XMIT_SUCCESS || err == NET_XMIT_CN) {
+        if (net_xmit_eval(err) == 0) {
                 stats->tx_bytes += pkt_len;
                 stats->tx_packets++;
         } else {
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 9a8e690fdf7c..9a88395a7629 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -502,8 +502,7 @@ static int tcp_v6_send_synack(struct sock *sk, struct request_sock *req,
 
                 ipv6_addr_copy(&fl.fl6_dst, &treq->rmt_addr);
                 err = ip6_xmit(sk, skb, &fl, opt, 0);
-                if (err == NET_XMIT_CN)
-                        err = 0;
+                err = net_xmit_eval(err);
         }
 
 done: