linux.git/include/linux/skbuff.h, branch v3.14-rc5

net: ip, ipv6: handle gso skbs in forwarding path

2014-02-13T22:17:02+00:00

Marcelo Ricardo Leitner reported problems when the forwarding link path
has a lower mtu than the incoming one if the inbound interface supports GRO.

Given:
Host  R1  R2

Host sends tcp stream which is routed via R1 and R2.  R1 performs GRO.

In this case, the kernel will fail to send ICMP fragmentation needed
messages (or pkt too big for ipv6), as GSO packets currently bypass dstmtu
checks in forward path. Instead, Linux tries to send out packets exceeding
the mtu.

When locking route MTU on Host (i.e., no ipv4 DF bit set), R1 does
not fragment the packets when forwarding, and again tries to send out
packets exceeding R1-R2 link mtu.

This alters the forwarding dstmtu checks to take the individual gso
segment lengths into account.

For ipv6, we send out pkt too big error for gso if the individual
segments are too big.

For ipv4, we either send icmp fragmentation needed, or, if the DF bit
is not set, perform software segmentation and let the output path
create fragments when the packet is leaving the machine.
It is not 100% correct as the error message will contain the headers of
the GRO skb instead of the original/segmented one, but it seems to
work fine in my (limited) tests.

Eric Dumazet suggested to simply shrink mss via ->gso_size to avoid
sofware segmentation.

However it turns out that skb_segment() assumes skb nr_frags is related
to mss size so we would BUG there.  I don't want to mess with it considering
Herbert and Eric disagree on what the correct behavior should be.

Hannes Frederic Sowa notes that when we would shrink gso_size
skb_segment would then also need to deal with the case where
SKB_MAX_FRAGS would be exceeded.

This uses sofware segmentation in the forward path when we hit ipv4
non-DF packets and the outgoing link mtu is too small.  Its not perfect,
but given the lack of bug reports wrt. GRO fwd being broken this is a
rare case anyway.  Also its not like this could not be improved later
once the dust settles.

Acked-by: Herbert Xu 
Reported-by: Marcelo Ricardo Leitner 
Signed-off-by: Florian Westphal 
Signed-off-by: David S. Miller

net: add and use skb_gso_transport_seglen()

2014-01-27T06:38:23+00:00

This moves part of Eric Dumazets skb_gso_seglen helper from tbf sched to
skbuff core so it may be reused by upcoming ip forwarding path patch.

Signed-off-by: Florian Westphal 
Acked-by: Eric Dumazet 
Signed-off-by: David S. Miller

net: Add skb_get_hash_raw

2014-01-17T00:22:54+00:00

Function to just return skb->rxhash without checking to see if it needs
to be recomputed.

Signed-off-by: Tom Herbert 
Acked-by: Eric Dumazet 
Signed-off-by: David S. Miller

net: add skb_checksum_setup

2014-01-14T22:24:19+00:00

This patch adds a function to set up the partial checksum offset for IP
packets (and optionally re-calculate the pseudo-header checksum) into the
core network code.
The implementation was previously private and duplicated between xen-netback
and xen-netfront, however it is not xen-specific and is potentially useful
to any network driver.

Signed-off-by: Paul Durrant 
Cc: David Miller 
Cc: Eric Dumazet 
Cc: Veaceslav Falico 
Cc: Alexander Duyck 
Cc: Nicolas Dichtel 
Signed-off-by: David S. Miller

net: skbuff: const-ify casts in skb_queue_* functions

2014-01-07T23:34:00+00:00

We should const-ify comparisons on skb_queue_* inline helper
functions as their parameters are const as well, so lets not
drop that.

Suggested-by: Brad Spengler 
Signed-off-by: Daniel Borkmann 
Signed-off-by: David S. Miller

Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/jesse/openvswitch

2014-01-07T00:48:38+00:00

Jesse Gross says:

====================
[GIT net-next] Open vSwitch

Open vSwitch changes for net-next/3.14. Highlights are:
 * Performance improvements in the mechanism to get packets to userspace
   using memory mapped netlink and skb zero copy where appropriate.
 * Per-cpu flow stats in situations where flows are likely to be shared
   across CPUs. Standard flow stats are used in other situations to save
   memory and allocation time.
 * A handful of code cleanups and rationalization.
====================

Signed-off-by: David S. Miller

net: Export skb_zerocopy() to zerocopy from one skb to another

2014-01-06T23:52:42+00:00

Make the skb zerocopy logic written for nfnetlink queue available for
use by other modules.

Signed-off-by: Thomas Graf 
Reviewed-by: Daniel Borkmann 
Acked-by: David S. Miller 
Signed-off-by: Jesse Gross

Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/davem/net

2014-01-06T22:37:45+00:00

Conflicts:
	drivers/net/ethernet/qlogic/qlcnic/qlcnic_sriov_pf.c
	net/ipv6/ip6_tunnel.c
	net/ipv6/ip6_vti.c

ipv6 tunnel statistic bug fixes conflicting with consolidation into
generic sw per-cpu net stats.

qlogic conflict between queue counting bug fix and the addition
of multiple MAC address support.

Signed-off-by: David S. Miller

net: Add some clarification to skb_tx_timestamp() comment.

2013-12-27T18:04:33+00:00

We've seen so many instances of people invoking skb_tx_timestamp()
after the device already has been given the packet, that it's worth
being a little bit more verbose and explicit in this comment.

Signed-off-by: David S. Miller

net: skbuff: improve comment on checksumming

2013-12-19T19:51:32+00:00

It can be a bit confusing when looking for checksumming flags that
the actual comment for this resides elsewhere further below in the
header file.

Thus, bring the documentation where we define these flags, and
slightly improve the doc text to make it a bit more clear/readable.

Also, whitespace-align values of the define while at it.

Signed-off-by: Daniel Borkmann 
Signed-off-by: David S. Miller