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[RFC,1/2] net: Add net_dev_start_xmit trace event, exposing more skb fields

Message ID 1381761660.1626.9.camel@bwh-desktop.uk.level5networks.com
State RFC, archived
Delegated to: David Miller
Headers show

Commit Message

Ben Hutchings Oct. 14, 2013, 2:41 p.m. UTC
The existing net/net_dev_xmit trace event provides little information
about the skb that has been passed to the driver, and it is not
simple to add more since the skb may already have been freed at
the point the event is emitted.

Add a separate trace event before the skb is passed to the driver,
including most fields that are likely to be interesting for debugging
driver datapath behaviour.

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
---
 include/trace/events/net.h | 58 ++++++++++++++++++++++++++++++++++++++++++++++
 net/core/dev.c             |  2 ++
 2 files changed, 60 insertions(+)
diff mbox

Patch

diff --git a/include/trace/events/net.h b/include/trace/events/net.h
index f99645d..0b61f2a 100644
--- a/include/trace/events/net.h
+++ b/include/trace/events/net.h
@@ -6,9 +6,67 @@ 
 
 #include <linux/skbuff.h>
 #include <linux/netdevice.h>
+#include <linux/if_vlan.h>
 #include <linux/ip.h>
 #include <linux/tracepoint.h>
 
+TRACE_EVENT(net_dev_start_xmit,
+
+	TP_PROTO(const struct sk_buff *skb, const struct net_device *dev),
+
+	TP_ARGS(skb, dev),
+
+	TP_STRUCT__entry(
+		__string(	name,			dev->name	)
+		__field(	u16,			queue_mapping	)
+		__field(	const void *,		skbaddr		)
+		__field(	bool,			vlan_tagged	)
+		__field(	u16,			vlan_proto	)
+		__field(	u16,			vlan_tci	)
+		__field(	u16,			protocol	)
+		__field(	u8,			ip_summed	)
+		__field(	unsigned int,		len		)
+		__field(	unsigned int,		data_len	)
+		__field(	int,			network_offset	)
+		__field(	bool,			transport_offset_valid)
+		__field(	int,			transport_offset)
+		__field(	u8,			tx_flags	)
+		__field(	u16,			gso_size	)
+		__field(	u16,			gso_segs	)
+		__field(	u16,			gso_type	)
+	),
+
+	TP_fast_assign(
+		__assign_str(name, dev->name);
+		__entry->queue_mapping = skb->queue_mapping;
+		__entry->skbaddr = skb;
+		__entry->vlan_tagged = vlan_tx_tag_present(skb);
+		__entry->vlan_proto = ntohs(skb->vlan_proto);
+		__entry->vlan_tci = vlan_tx_tag_get(skb);
+		__entry->protocol = ntohs(skb->protocol);
+		__entry->ip_summed = skb->ip_summed;
+		__entry->len = skb->len;
+		__entry->data_len = skb->data_len;
+		__entry->network_offset = skb_network_offset(skb);
+		__entry->transport_offset_valid =
+			skb_transport_header_was_set(skb);
+		__entry->transport_offset = skb_transport_offset(skb);
+		__entry->tx_flags = skb_shinfo(skb)->tx_flags;
+		__entry->gso_size = skb_shinfo(skb)->gso_size;
+		__entry->gso_segs = skb_shinfo(skb)->gso_segs;
+		__entry->gso_type = skb_shinfo(skb)->gso_type;
+	),
+
+	TP_printk("dev=%s queue_mapping=%u skbaddr=%p vlan_tagged=%d vlan_proto=0x%04x vlan_tci=0x%04x protocol=0x%04x ip_summed=%d len=%u data_len=%u network_offset=%d transport_offset_valid=%d transport_offset=%d tx_flags=%d gso_size=%d gso_segs=%d gso_type=%#x",
+		  __get_str(name), __entry->queue_mapping, __entry->skbaddr,
+		  __entry->vlan_tagged, __entry->vlan_proto, __entry->vlan_tci,
+		  __entry->protocol, __entry->ip_summed, __entry->len,
+		  __entry->data_len, 
+		  __entry->network_offset, __entry->transport_offset_valid,
+		  __entry->transport_offset, __entry->tx_flags,
+		  __entry->gso_size, __entry->gso_segs, __entry->gso_type)
+);
+
 TRACE_EVENT(net_dev_xmit,
 
 	TP_PROTO(struct sk_buff *skb,
diff --git a/net/core/dev.c b/net/core/dev.c
index 1b6eadf..e221963 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -2602,6 +2602,7 @@  int dev_hard_start_xmit(struct sk_buff *skb, struct net_device *dev,
 			dev_queue_xmit_nit(skb, dev);
 
 		skb_len = skb->len;
+		trace_net_dev_start_xmit(skb, dev);
 		rc = ops->ndo_start_xmit(skb, dev);
 		trace_net_dev_xmit(skb, rc, dev, skb_len);
 		if (rc == NETDEV_TX_OK)
@@ -2620,6 +2621,7 @@  gso:
 			dev_queue_xmit_nit(nskb, dev);
 
 		skb_len = nskb->len;
+		trace_net_dev_start_xmit(nskb, dev);
 		rc = ops->ndo_start_xmit(nskb, dev);
 		trace_net_dev_xmit(nskb, rc, dev, skb_len);
 		if (unlikely(rc != NETDEV_TX_OK)) {