android_kernel_xiaomi_sm8350/net
Neil Horman 977750076d af_packet: add interframe drop cmsg (v6)
Add Ancilliary data to better represent loss information

I've had a few requests recently to provide more detail regarding frame loss
during an AF_PACKET packet capture session.  Specifically the requestors want to
see where in a packet sequence frames were lost, i.e. they want to see that 40
frames were lost between frames 302 and 303 in a packet capture file.  In order
to do this we need:

1) The kernel to export this data to user space
2) The applications to make use of it

This patch addresses item (1).  It does this by doing the following:

A) Anytime we drop a frame for which we would increment po->stats.tp_drops, we
also no increment a stats called po->stats.tp_gap.

B) Every time we successfully enqueue a frame to sk_receive_queue, we record the
value of po->stats.tp_gap in skb->mark.  skb->cb would nominally be the place to
record this, but since all the space there is used up, we're overloading
skb->mark.  Its safe to do since any enqueued packet is guaranteed to be
unshared at this point, and skb->mark isn't used for anything else in the rx
path to the application.  After we record tp_gap in the skb, we zero
po->stats.tp_gap.  This allows us to keep a counter of the number of frames lost
between any two enqueued packets

C) When the application goes to dequeue a frame from the packet socket, we look
at skb->mark for that frame.  If it is non-zero, we add a cmsg chunk to the
msghdr of level SOL_PACKET and type PACKET_GAPDATA.  Its a 32 bit integer that
represents the number of frames lost between this packet and the last previous
frame received.

Note there is a chance that if there is frame loss after a receive, and then the
socket is closed, some gap data might be lost.  This is covered by the use of
the PACKET_AUXDATA socket option, which gives total loss data.  With a bit of
math, the final gap can be determined that way.

I've tested this patch myself, and it works well.

Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>

 include/linux/if_packet.h |    2 ++
 net/packet/af_packet.c    |   33 +++++++++++++++++++++++++++++++++
 2 files changed, 35 insertions(+)
Signed-off-by: David S. Miller <davem@davemloft.net>
2009-10-05 00:21:55 -07:00
..
9p virtio: add virtio IDs file 2009-09-23 22:26:32 +09:30
802 net: remove COMPAT_NET_DEV_OPS 2009-05-25 01:53:53 -07:00
8021q net: fix vlan_get_size to include vlan_flags size 2009-09-26 20:16:07 -07:00
appletalk Have atalk_route_packet() return NET_RX_SUCCESS not NET_XMIT_SUCCESS 2009-09-14 17:02:47 -07:00
atm net: Make setsockopt() optlen be unsigned. 2009-09-30 16:12:20 -07:00
ax25 ax25: Fix possible oops in ax25_make_new 2009-09-30 16:44:12 -07:00
bluetooth net: Make setsockopt() optlen be unsigned. 2009-09-30 16:12:20 -07:00
bridge bridge: Fix double-free in br_add_if. 2009-09-28 12:54:25 -07:00
can net: Make setsockopt() optlen be unsigned. 2009-09-30 16:12:20 -07:00
core pktgen: Avoid dirtying skb->users when txq is full 2009-10-05 00:21:54 -07:00
dcb net: fix double skb free in dcbnl 2009-09-26 20:16:15 -07:00
dccp net: Make setsockopt() optlen be unsigned. 2009-09-30 16:12:20 -07:00
decnet net: Make setsockopt() optlen be unsigned. 2009-09-30 16:12:20 -07:00
dsa netdev: convert pseudo-devices to netdev_tx_t 2009-09-01 01:13:07 -07:00
econet Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6 2009-08-12 17:44:53 -07:00
ethernet net: remove COMPAT_NET_DEV_OPS 2009-05-25 01:53:53 -07:00
ieee802154 net: Make setsockopt() optlen be unsigned. 2009-09-30 16:12:20 -07:00
ipv4 icmp: No need to call sk_write_space() 2009-10-05 00:21:54 -07:00
ipv6 sit: fix off-by-one in ipip6_tunnel_get_prl 2009-09-30 16:39:27 -07:00
ipx net: Make setsockopt() optlen be unsigned. 2009-09-30 16:12:20 -07:00
irda net: Make setsockopt() optlen be unsigned. 2009-09-30 16:12:20 -07:00
iucv net: Make setsockopt() optlen be unsigned. 2009-09-30 16:12:20 -07:00
key net: file_operations should be const 2009-09-02 01:03:53 -07:00
lapb net: remove NET_RX_BAD and NET_RX_CN* defines 2009-07-05 19:15:35 -07:00
llc net: Make setsockopt() optlen be unsigned. 2009-09-30 16:12:20 -07:00
mac80211 mac80211: Fix [re]association power saving issue on AP side 2009-09-29 17:25:15 -04:00
netfilter net: Make setsockopt() optlen be unsigned. 2009-09-30 16:12:20 -07:00
netlabel Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6 2009-07-30 19:22:43 -07:00
netlink net: Make setsockopt() optlen be unsigned. 2009-09-30 16:12:20 -07:00
netrom net: Make setsockopt() optlen be unsigned. 2009-09-30 16:12:20 -07:00
packet af_packet: add interframe drop cmsg (v6) 2009-10-05 00:21:55 -07:00
phonet Phonet: fix mutex imbalance 2009-09-30 16:41:34 -07:00
rds net: Make setsockopt() optlen be unsigned. 2009-09-30 16:12:20 -07:00
rfkill headers: remove sched.h from poll.h 2009-10-04 15:05:10 -07:00
rose net: Make setsockopt() optlen be unsigned. 2009-09-30 16:12:20 -07:00
rxrpc net: Make setsockopt() optlen be unsigned. 2009-09-30 16:12:20 -07:00
sched trivial: fix typo "to to" in multiple files 2009-09-21 15:14:55 +02:00
sctp net: Make setsockopt() optlen be unsigned. 2009-09-30 16:12:20 -07:00
sunrpc net: fix htmldocs sunrpc, clnt.c 2009-09-24 15:39:14 -07:00
tipc net: Make setsockopt() optlen be unsigned. 2009-09-30 16:12:20 -07:00
unix net: unix: fix sending fds in multiple buffers 2009-09-11 11:31:45 -07:00
wanrouter headers: smp_lock.h redux 2009-07-12 12:22:34 -07:00
wimax wimax: fix warning caused by not checking retval of rfkill_set_hw_state() 2009-06-11 11:12:48 -07:00
wireless wext: add back wireless/ dir in sysfs for cfg80211 interfaces 2009-09-28 16:55:07 -04:00
x25 net: Make setsockopt() optlen be unsigned. 2009-09-30 16:12:20 -07:00
xfrm net: file_operations should be const 2009-09-02 01:03:53 -07:00
compat.c net: Make setsockopt() optlen be unsigned. 2009-09-30 16:12:20 -07:00
Kconfig net/compat/wext: send different messages to compat tasks 2009-07-15 08:53:39 -07:00
Makefile net: remove redundant sched/ in net/Makefile 2009-07-12 20:11:14 -07:00
nonet.c
socket.c net: Make setsockopt() optlen be unsigned. 2009-09-30 16:12:20 -07:00
sysctl_net.c
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