linux-stable.git/include/linux/skbuff.h, branch v3.17.2

net: Always untag vlan-tagged traffic on input.

2014-08-11T19:16:51+00:00

Currently the functionality to untag traffic on input resides
as part of the vlan module and is build only when VLAN support
is enabled in the kernel.  When VLAN is disabled, the function
vlan_untag() turns into a stub and doesn't really untag the
packets.  This seems to create an interesting interaction
between VMs supporting checksum offloading and some network drivers.

There are some drivers that do not allow the user to change
tx-vlan-offload feature of the driver.  These drivers also seem
to assume that any VLAN-tagged traffic they transmit will
have the vlan information in the vlan_tci and not in the vlan
header already in the skb.  When transmitting skbs that already
have tagged data with partial checksum set, the checksum doesn't
appear to be updated correctly by the card thus resulting in a
failure to establish TCP connections.

The following is a packet trace taken on the receiver where a
sender is a VM with a VLAN configued.  The host VM is running on
doest not have VLAN support and the outging interface on the
host is tg3:
10:12:43.503055 52:54:00:ae:42:3f > 28:d2:44:7d:c2:de, ethertype 802.1Q
(0x8100), length 78: vlan 100, p 0, ethertype IPv4, (tos 0x0, ttl 64, id 27243,
offset 0, flags [DF], proto TCP (6), length 60)
    10.0.100.1.58545 > 10.0.100.10.ircu-2: Flags [S], cksum 0xdc39 (incorrect
-> 0x48d9), seq 1069378582, win 29200, options [mss 1460,sackOK,TS val
4294837885 ecr 0,nop,wscale 7], length 0
10:12:44.505556 52:54:00:ae:42:3f > 28:d2:44:7d:c2:de, ethertype 802.1Q
(0x8100), length 78: vlan 100, p 0, ethertype IPv4, (tos 0x0, ttl 64, id 27244,
offset 0, flags [DF], proto TCP (6), length 60)
    10.0.100.1.58545 > 10.0.100.10.ircu-2: Flags [S], cksum 0xdc39 (incorrect
-> 0x44ee), seq 1069378582, win 29200, options [mss 1460,sackOK,TS val
4294838888 ecr 0,nop,wscale 7], length 0

This connection finally times out.

I've only access to the TG3 hardware in this configuration thus have
only tested this with TG3 driver.  There are a lot of other drivers
that do not permit user changes to vlan acceleration features, and
I don't know if they all suffere from a similar issue.

The patch attempt to fix this another way.  It moves the vlan header
stipping code out of the vlan module and always builds it into the
kernel network core.  This way, even if vlan is not supported on
a virtualizatoin host, the virtual machines running on top of such
host will still work with VLANs enabled.

CC: Patrick McHardy 
CC: Nithin Nayak Sujir 
CC: Michael Chan 
CC: Jiri Pirko 
Signed-off-by: Vladislav Yasevich 
Acked-by: Jiri Pirko 
Signed-off-by: David S. Miller

net-timestamp: ACK timestamp for bytestreams

2014-08-05T23:35:54+00:00

Add SOF_TIMESTAMPING_TX_ACK, a request for a tstamp when the last byte
in the send() call is acknowledged. It implements the feature for TCP.

The timestamp is generated when the TCP socket cumulative ACK is moved
beyond the tracked seqno for the first time. The feature ignores SACK
and FACK, because those acknowledge the specific byte, but not
necessarily the entire contents of the buffer up to that byte.

Signed-off-by: Willem de Bruijn 
Signed-off-by: David S. Miller

net-timestamp: SCHED timestamp on entering packet scheduler

2014-08-05T23:35:54+00:00

Kernel transmit latency is often incurred in the packet scheduler.
Introduce a new timestamp on transmission just before entering the
scheduler. When data travels through multiple devices (bonding,
tunneling, ...) each device will export an individual timestamp.

Signed-off-by: Willem de Bruijn 
Signed-off-by: David S. Miller

net-timestamp: add key to disambiguate concurrent datagrams

2014-08-05T23:35:54+00:00

Datagrams timestamped on transmission can coexist in the kernel stack
and be reordered in packet scheduling. When reading looped datagrams
from the socket error queue it is not always possible to unique
correlate looped data with original send() call (for application
level retransmits). Even if possible, it may be expensive and complex,
requiring packet inspection.

Introduce a data-independent ID mechanism to associate timestamps with
send calls. Pass an ID alongside the timestamp in field ee_data of
sock_extended_err.

The ID is a simple 32 bit unsigned int that is associated with the
socket and incremented on each send() call for which software tx
timestamp generation is enabled.

The feature is enabled only if SOF_TIMESTAMPING_OPT_ID is set, to
avoid changing ee_data for existing applications that expect it 0.
The counter is reset each time the flag is reenabled. Reenabling
does not change the ID of already submitted data. It is possible
to receive out of order IDs if the timestamp stream is not quiesced
first.

Signed-off-by: Willem de Bruijn 
Signed-off-by: David S. Miller

net-timestamp: extend SCM_TIMESTAMPING ancillary data struct

2014-08-05T23:35:53+00:00

Applications that request kernel tx timestamps with SO_TIMESTAMPING
read timestamps as recvmsg() ancillary data. The response is defined
implicitly as timespec[3].

1) define struct scm_timestamping explicitly and

2) add support for new tstamp types. On tx, scm_timestamping always
   accompanies a sock_extended_err. Define previously unused field
   ee_info to signal the type of ts[0]. Introduce SCM_TSTAMP_SND to
   define the existing behavior.

The reception path is not modified. On rx, no struct similar to
sock_extended_err is passed along with SCM_TIMESTAMPING.

Signed-off-by: Willem de Bruijn 
Signed-off-by: David S. Miller

net: remove deprecated syststamp timestamp

2014-07-29T18:39:50+00:00

The SO_TIMESTAMPING API defines three types of timestamps: software,
hardware in raw format (hwtstamp) and hardware converted to system
format (syststamp). The last has been deprecated in favor of combining
hwtstamp with a PTP clock driver. There are no active users in the
kernel.

The option was device driver dependent. If set, but without hardware
support, the correct behavior is to return zero in the relevant field
in the SCM_TIMESTAMPING ancillary message. Without device drivers
implementing the option, this field is effectively always zero.

Remove the internal plumbing to dissuage new drivers from implementing
the feature. Keep the SOF_TIMESTAMPING_SYS_HARDWARE flag, however, to
avoid breaking existing applications that request the timestamp.

Signed-off-by: Willem de Bruijn 
Signed-off-by: David S. Miller

net: skbuff: Use ALIGN macro instead of open coding it

2014-07-22T20:39:42+00:00

Use ALIGN from linux/kernel.h to define SKB_DATA_ALIGN instead of open
coding it.

Signed-off-by: Tobias Klauser 
Signed-off-by: David S. Miller

net-timestamp: document deprecated syststamp

2014-07-15T23:32:45+00:00

The SO_TIMESTAMPING API defines option SOF_TIMESTAMPING_SYS_HW.
This feature is deprecated. It should not be implemented by new
device drivers. Existing drivers do not implement it, either --
with one exception.

Driver developers are encouraged to expose the NIC hw clock as a
PTP HW clock source, instead, and synchronize system time to the
HW source.

The control flag cannot be removed due to being part of the ABI, nor
can the structure scm_timestamping that is returned. Due to the one
legacy driver, the internal datapath and structure are not removed.

This patch only clearly marks the interface as deprecated. Device
drivers should always return a syststamp value of zero.

Signed-off-by: Willem de Bruijn 

----

We can consider adding a WARN_ON_ONCE in__sock_recv_timestamp
if non-zero syststamp is encountered
Acked-by: Richard Cochran 
Signed-off-by: David S. Miller

net: Only do flow_dissector hash computation once per packet

2014-07-08T04:14:21+00:00

Add sw_hash flag to skbuff to indicate that skb->hash was computed
from flow_dissector. This flag is checked in skb_get_hash to avoid
repeatedly trying to compute the hash (ie. in the case that no L4 hash
can be computed).

Signed-off-by: Tom Herbert 
Signed-off-by: David S. Miller

net: Call skb_get_hash in get_xps_queue and __skb_tx_hash

2014-07-08T04:14:21+00:00

Call standard function to get a packet hash instead of taking this from
skb->sk->sk_hash or only using skb->protocol.

Signed-off-by: Tom Herbert 
Signed-off-by: David S. Miller