[RFC PATCH 2/2] netdev: Add tracepoint to netif_receive_skb

[Koki Sanagi <sanagi.koki@jp.fujitsu.com>]

This patch adds tracepoint to netif_receive_skb.
It notices that receive packet passes network/driver interface.
An output is below.

<idle>-0     [001] 68238.417058: netdev_receive_skb: dev=eth3 skbaddr=f3c81540 len=52
<idle>-0     [001] 68238.704363: netdev_receive_skb: dev=eth3 skbaddr=f3c81540 len=100
<idle>-0     [001] 68238.706891: netdev_receive_skb: dev=eth3 skbaddr=f3c81540 len=52
<idle>-0     [001] 68238.878736: netdev_receive_skb: dev=eth3 skbaddr=f3c81540 len=100

Signed-off-by: Koki Sanagi <sanagi.koki@jp.fujitsu.com>
---
  include/trace/events/skb.h |   28 ++++++++++++++++++++++++++++
  net/core/dev.c             |    1 +
  2 files changed, 29 insertions(+), 0 deletions(-)

diff --git a/include/trace/events/skb.h b/include/trace/events/skb.h
index 425a062..ca78d49 100644
--- a/include/trace/events/skb.h
+++ b/include/trace/events/skb.h
@@ -37,6 +37,34 @@ TRACE_EVENT(netdev_start_xmit,
  );
  
  /*
+ * netdev_receive_skb - invoked when skb is received from the driver
+ * @skb:		pointer to struct sk_buff
+ * @dev:		pointer to struct net_device
+ */
+TRACE_EVENT(netdev_receive_skb,
+
+	TP_PROTO(struct sk_buff *skb,
+		 struct net_device *dev),
+
+	TP_ARGS(skb, dev),
+
+	TP_STRUCT__entry(
+		__field(	const void *, 	skbaddr		)
+		__field(	unsigned int, 	len		)
+		__string(	name, 		dev->name	)
+       ),
+
+	TP_fast_assign(
+		__entry->skbaddr = skb;
+		__entry->len = skb->len;
+		__assign_str(name, dev->name);
+	),
+
+	TP_printk("dev=%s skbaddr=%p len=%u",
+		__get_str(name), __entry->skbaddr, __entry->len)
+);
+
+/*
   * Tracepoint for free an sk_buff:
   */
  TRACE_EVENT(kfree_skb,
diff --git a/net/core/dev.c b/net/core/dev.c
index 4667a96..7281286 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -2683,6 +2683,7 @@ static int __netif_receive_skb(struct sk_buff *skb)
  
  	__get_cpu_var(netdev_rx_stat).total++;
  
+	trace_netdev_receive_skb(skb, orig_dev);
  	skb_reset_network_header(skb);
  	skb_reset_transport_header(skb);
  	skb->mac_len = skb->network_header - skb->mac_header;