From: Neil Horman <nhorman@redhat.com>
Date: Tue, 15 Dec 2009 00:57:16 -0500
Subject: [net] add send/receive tracepoints
Message-id: <20091215005716.GB2898@localhost.localdomain>
Patchwork-id: 21934
O-Subject: [RHEL 5.5 PATCH] net: add send/receive tracepoints (bz 475457)
Bugzilla: 475457
RH-Acked-by: Jason Baron <jbaron@redhat.com>

Hey all-
	This is a patch to add tracepoints to the end of the tx path and the
start of the rx path in the network stack.  They're not upstream yet, but I'll
be proposing them shortly as part of my port mirroring feature.  Fujitsu was
hoping to get them into 5.5 for some other apps of theirs, so I'm posting the
tracepoints, without the rest of the port mirroring code here.  I've tested the
tracepoints myself in rhts, and they've worked well.  When off, theres no
measureable impact on network throughput. Satisfies bz 475457

Neil

Signed-off-by: Jarod Wilson <jarod@redhat.com>

diff --git a/include/trace/net.h b/include/trace/net.h
new file mode 100644
index 0000000..1cde93b
--- /dev/null
+++ b/include/trace/net.h
@@ -0,0 +1,13 @@
+#ifndef _TRACE_NET_H_
+#define _TRACE_NET_H_
+
+#include <linux/tracepoint.h>
+
+DEFINE_TRACE(net_dev_xmit,
+	TPPROTO(struct sk_buff *skb, int rc),
+	TPARGS(skb, rc));
+
+DEFINE_TRACE(net_dev_receive,
+	TPPROTO(struct sk_buff *skb),
+	TPARGS(skb));
+#endif
diff --git a/net/core/dev.c b/net/core/dev.c
index 9f5f1fa..e9a472f 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -118,6 +118,7 @@
 #include <linux/err.h>
 #include <linux/ctype.h>
 #include <trace/napi.h>
+#include <trace/net.h>
 
 #ifdef CONFIG_XEN
 #include <net/ip.h>
@@ -1417,6 +1418,7 @@ static int dev_gso_segment(struct sk_buff *skb)
 
 int dev_hard_start_xmit(struct sk_buff *skb, struct net_device *dev)
 {
+	int rc;
 	if (likely(!skb->next)) {
 		if (netdev_nit)
 			dev_queue_xmit_nit(skb, dev);
@@ -1428,17 +1430,19 @@ int dev_hard_start_xmit(struct sk_buff *skb, struct net_device *dev)
 				goto gso;
 		}
 
-		return dev->hard_start_xmit(skb, dev);
+		rc = dev->hard_start_xmit(skb, dev);
+		trace_net_dev_xmit(skb, rc);
+		return rc;
 	}
 
 gso:
 	do {
 		struct sk_buff *nskb = skb->next;
-		int rc;
 
 		skb->next = nskb->next;
 		nskb->next = NULL;
 		rc = dev->hard_start_xmit(nskb, dev);
+		trace_net_dev_xmit(skb, rc);
 		if (unlikely(rc)) {
 			nskb->next = skb->next;
 			skb->next = nskb;
@@ -1875,6 +1879,8 @@ int netif_receive_skb(struct sk_buff *skb)
 	int ret = NET_RX_DROP;
 	unsigned short type;
 
+	trace_net_dev_receive(skb);
+
 	/* if we've gotten here through NAPI, check netpoll */
 	if (skb->dev->poll && netpoll_rx(skb))
 		return NET_RX_DROP;
diff --git a/net/core/net-traces.c b/net/core/net-traces.c
index b07b25b..53b8d0e 100644
--- a/net/core/net-traces.c
+++ b/net/core/net-traces.c
@@ -21,6 +21,7 @@
 #include <linux/net_dropmon.h>
 #include <trace/skb.h>
 #include <trace/napi.h>
+#include <trace/net.h>
 
 #include <asm/unaligned.h>
 #include <asm/bitops.h>
@@ -31,3 +32,10 @@ EXPORT_TRACEPOINT_SYMBOL_GPL(kfree_skb);
 
 DEFINE_TRACE(napi_poll);
 EXPORT_TRACEPOINT_SYMBOL_GPL(napi_poll);
+
+DEFINE_TRACE(net_dev_xmit);
+EXPORT_TRACEPOINT_SYMBOL_GPL(net_dev_xmit);
+
+DEFINE_TRACE(net_dev_receive);
+EXPORT_TRACEPOINT_SYMBOL_GPL(net_dev_receive);
+