Commit d87d04a7 authored by Ben Hutchings's avatar Ben Hutchings Committed by David S. Miller
Browse files

net: Add net_dev_start_xmit trace event, exposing more skb fields 



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: default avatarBen Hutchings <bhutchings@solarflare.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 20567661

include/trace/events/net.h

+58 −0
Original line number Diff line number Diff line
@@ -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,

net/core/dev.c

+2 −0
Original line number Diff line number Diff line
@@ -2596,6 +2596,7 @@ 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)
@@ -2614,6 +2615,7 @@ 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)) {

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