From 38aeef15d85c8f7a590ebf3daaeb3f4d72d414a4 Mon Sep 17 00:00:00 2001
From: Jesse Gross <jesse@nicira.com>
Date: Mon, 12 Jul 2010 13:27:57 -0700
Subject: [PATCH] datapath: Move over-MTU checking into vport_send().

We currently check for packets that are over the MTU in do_output().
There is a one-to-one correlation between this function and
vport_send() so move the MTU check there for consistency with
other error checking.
---
 datapath/actions.c | 16 ----------------
 datapath/vport.c   | 41 +++++++++++++++++++++++++++++++++--------
 2 files changed, 33 insertions(+), 24 deletions(-)

diff --git a/datapath/actions.c b/datapath/actions.c
index f7e51d92..131548c7 100644
--- a/datapath/actions.c
+++ b/datapath/actions.c
@@ -347,19 +347,10 @@ set_tp_port(struct sk_buff *skb, struct odp_flow_key *key,
 	return skb;
 }
 
-static inline unsigned packet_length(const struct sk_buff *skb)
-{
-	unsigned length = skb->len - ETH_HLEN;
-	if (skb->protocol == htons(ETH_P_8021Q))
-		length -= VLAN_HLEN;
-	return length;
-}
-
 static void
 do_output(struct datapath *dp, struct sk_buff *skb, int out_port)
 {
 	struct dp_port *p;
-	int mtu;
 
 	if (!skb)
 		goto error;
@@ -368,13 +359,6 @@ do_output(struct datapath *dp, struct sk_buff *skb, int out_port)
 	if (!p)
 		goto error;
 
-	mtu = vport_get_mtu(p->vport);
-	if (packet_length(skb) > mtu && !skb_is_gso(skb)) {
-		printk(KERN_WARNING "%s: dropped over-mtu packet: %d > %d\n",
-		       dp_name(dp), packet_length(skb), mtu);
-		goto error;
-	}
-
 	vport_send(p->vport, skb);
 	return;
 
diff --git a/datapath/vport.c b/datapath/vport.c
index 13039505..ef07a091 100644
--- a/datapath/vport.c
+++ b/datapath/vport.c
@@ -9,6 +9,7 @@
 #include <linux/dcache.h>
 #include <linux/etherdevice.h>
 #include <linux/if.h>
+#include <linux/if_vlan.h>
 #include <linux/kernel.h>
 #include <linux/list.h>
 #include <linux/mutex.h>
@@ -1275,6 +1276,17 @@ vport_receive(struct vport *vport, struct sk_buff *skb)
 	dp_process_received_packet(dp_port, skb);
 }
 
+static inline unsigned
+packet_length(const struct sk_buff *skb)
+{
+	unsigned length = skb->len - ETH_HLEN;
+
+	if (skb->protocol == htons(ETH_P_8021Q))
+		length -= VLAN_HLEN;
+
+	return length;
+}
+
 /**
  *	vport_send - send a packet on a device
  *
@@ -1288,25 +1300,28 @@ int
 vport_send(struct vport *vport, struct sk_buff *skb)
 {
 	int *loop_count;
+	int mtu;
 	int sent;
 
 	loop_count = &per_cpu_ptr(vport_loop_counter, get_cpu())->count[!!in_interrupt()];
 	(*loop_count)++;
 
-	if (likely(*loop_count <= VPORT_MAX_LOOPS)) {
-		sent = vport->ops->send(vport, skb);
-	} else {
+	if (unlikely(*loop_count > VPORT_MAX_LOOPS)) {
 		if (net_ratelimit())
 			printk(KERN_WARNING "%s: dropping packet that has looped more than %d times\n",
 			       dp_name(vport_get_dp_port(vport)->dp), VPORT_MAX_LOOPS);
+		goto error;
+	}
 
-		sent = 0;
-		kfree_skb(skb);
-		vport_record_error(vport, VPORT_E_TX_DROPPED);
+	mtu = vport_get_mtu(vport);
+	if (unlikely(packet_length(skb) > mtu && !skb_is_gso(skb))) {
+		if (net_ratelimit())
+			printk(KERN_WARNING "%s: dropped over-mtu packet: %d > %d\n",
+			       dp_name(vport_get_dp_port(vport)->dp), packet_length(skb), mtu);
+		goto error;
 	}
 
-	(*loop_count)--;
-	put_cpu();
+	sent = vport->ops->send(vport, skb);
 
 	if (vport->ops->flags & VPORT_F_GEN_STATS && sent > 0) {
 		struct vport_percpu_stats *stats;
@@ -1320,6 +1335,16 @@ vport_send(struct vport *vport, struct sk_buff *skb)
 		local_bh_enable();
 	}
 
+	goto out;
+
+error:
+	sent = 0;
+	kfree_skb(skb);
+	vport_record_error(vport, VPORT_E_TX_DROPPED);
+out:
+	(*loop_count)--;
+	put_cpu();
+
 	return sent;
 }
 
-- 
2.30.2