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packet_mmap: expose hw packet timestamps to network packet capture utilities 

This patch adds a setting, PACKET_TIMESTAMP, to specify the packet
timestamp source that is exported to capture utilities like tcpdump by
packet_mmap.

PACKET_TIMESTAMP accepts the same integer bit field as
SO_TIMESTAMPING.  However, only the SOF_TIMESTAMPING_SYS_HARDWARE and
SOF_TIMESTAMPING_RAW_HARDWARE values are currently recognized by
PACKET_TIMESTAMP.  SOF_TIMESTAMPING_SYS_HARDWARE takes precedence over
SOF_TIMESTAMPING_RAW_HARDWARE if both bits are set.

If PACKET_TIMESTAMP is not set, a software timestamp generated inside
the networking stack is used (the behavior before this setting was
added).

Signed-off-by: Scott McMillan <scott.a.mcmillan@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Scott McMillan 2010-06-02 05:53:56 -07:00 committed by David S. Miller
parent 7dad171c39
commit 614f60fa9d
3 changed files with 62 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

26
Documentation/networking/packet_mmap.txt
View File

@ -493,6 +493,32 @@ The user can also use poll() to check if a buffer is available:
pfd.events = POLLOUT;
retval = poll(&pfd, 1, timeout);
-------------------------------------------------------------------------------
+ PACKET_TIMESTAMP
-------------------------------------------------------------------------------
The PACKET_TIMESTAMP setting determines the source of the timestamp in
the packet meta information. If your NIC is capable of timestamping
packets in hardware, you can request those hardware timestamps to used.
Note: you may need to enable the generation of hardware timestamps with
SIOCSHWTSTAMP.
PACKET_TIMESTAMP accepts the same integer bit field as
SO_TIMESTAMPING. However, only the SOF_TIMESTAMPING_SYS_HARDWARE
and SOF_TIMESTAMPING_RAW_HARDWARE values are recognized by
PACKET_TIMESTAMP. SOF_TIMESTAMPING_SYS_HARDWARE takes precedence over
SOF_TIMESTAMPING_RAW_HARDWARE if both bits are set.
int req = 0;
req |= SOF_TIMESTAMPING_SYS_HARDWARE;
setsockopt(fd, SOL_PACKET, PACKET_TIMESTAMP, (void *) &req, sizeof(req))
If PACKET_TIMESTAMP is not set, a software timestamp generated inside
the networking stack is used (the behavior before this setting was added).
See include/linux/net_tstamp.h and Documentation/networking/timestamping
for more information on hardware timestamps.
--------------------------------------------------------------------------------
+ THANKS
--------------------------------------------------------------------------------

1
include/linux/if_packet.h
View File

@ -48,6 +48,7 @@ struct sockaddr_ll {
#define PACKET_LOSS 14
#define PACKET_VNET_HDR 15
#define PACKET_TX_TIMESTAMP 16
#define PACKET_TIMESTAMP 17
struct tpacket_stats {
unsigned int tp_packets;

37
net/packet/af_packet.c
View File

@ -83,6 +83,7 @@
#include <linux/if_vlan.h>
#include <linux/virtio_net.h>
#include <linux/errqueue.h>
#include <linux/net_tstamp.h>
#ifdef CONFIG_INET
#include <net/inet_common.h>
@ -202,6 +203,7 @@ struct packet_sock {
unsigned int tp_hdrlen;
unsigned int tp_reserve;
unsigned int tp_loss:1;
unsigned int tp_tstamp;
struct packet_type prot_hook ____cacheline_aligned_in_smp;
};
@ -656,6 +658,7 @@ static int tpacket_rcv(struct sk_buff *skb, struct net_device *dev,
struct sk_buff *copy_skb = NULL;
struct timeval tv;
struct timespec ts;
struct skb_shared_hwtstamps *shhwtstamps = skb_hwtstamps(skb);
if (skb->pkt_type == PACKET_LOOPBACK)
goto drop;
@ -737,7 +740,13 @@ static int tpacket_rcv(struct sk_buff *skb, struct net_device *dev,
h.h1->tp_snaplen = snaplen;
h.h1->tp_mac = macoff;
h.h1->tp_net = netoff;
if (skb->tstamp.tv64)
if ((po->tp_tstamp & SOF_TIMESTAMPING_SYS_HARDWARE)
&& shhwtstamps->syststamp.tv64)
tv = ktime_to_timeval(shhwtstamps->syststamp);
else if ((po->tp_tstamp & SOF_TIMESTAMPING_RAW_HARDWARE)
&& shhwtstamps->hwtstamp.tv64)
tv = ktime_to_timeval(shhwtstamps->hwtstamp);
else if (skb->tstamp.tv64)
tv = ktime_to_timeval(skb->tstamp);
else
do_gettimeofday(&tv);
@ -750,7 +759,13 @@ static int tpacket_rcv(struct sk_buff *skb, struct net_device *dev,
h.h2->tp_snaplen = snaplen;
h.h2->tp_mac = macoff;
h.h2->tp_net = netoff;
if (skb->tstamp.tv64)
if ((po->tp_tstamp & SOF_TIMESTAMPING_SYS_HARDWARE)
&& shhwtstamps->syststamp.tv64)
ts = ktime_to_timespec(shhwtstamps->syststamp);
else if ((po->tp_tstamp & SOF_TIMESTAMPING_RAW_HARDWARE)
&& shhwtstamps->hwtstamp.tv64)
ts = ktime_to_timespec(shhwtstamps->hwtstamp);
else if (skb->tstamp.tv64)
ts = ktime_to_timespec(skb->tstamp);
else
getnstimeofday(&ts);
@ -2027,6 +2042,18 @@ packet_setsockopt(struct socket *sock, int level, int optname, char __user *optv
po->has_vnet_hdr = !!val;
return 0;
}
case PACKET_TIMESTAMP:
{
int val;
if (optlen != sizeof(val))
return -EINVAL;
if (copy_from_user(&val, optval, sizeof(val)))
return -EFAULT;
po->tp_tstamp = val;
return 0;
}
default:
return -ENOPROTOOPT;
}
@ -2119,6 +2146,12 @@ static int packet_getsockopt(struct socket *sock, int level, int optname,
val = po->tp_loss;
data = &val;
break;
case PACKET_TIMESTAMP:
if (len > sizeof(int))
len = sizeof(int);
val = po->tp_tstamp;
data = &val;
break;
default:
return -ENOPROTOOPT;
}