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net: Add net_dev_start_xmit trace event, exposing more skb fields

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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>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Ben Hutchings 2014-01-10 22:17:03 +00:00 committed by David S. Miller
parent 20567661a1
commit d87d04a785
2 changed files with 60 additions and 0 deletions
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58
include/trace/events/net.h
View file

@ -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,

2
net/core/dev.c
View file

@ -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)) {