Signed-off-by: NHariprasad Shenai <hariprasad@chelsio.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

We need to clear delayed kick counters when we free rings otherwise
after ndo_close()/ndo_open() we could kick HW by more entries than
actually written to rings.
Signed-off-by: NJakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: NRolf Neugebauer <rolf.neugebauer@netronome.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

If a tun interface is turned down, we should not allow packet injection
into the kernel.

Kernel does not send packets to the tun already.

TUNATTACHFILTER can not be used as only tun_net_xmit() is taking care
of it.
Reported-by: NCurt Wohlgemuth <curtw@google.com>
Signed-off-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Same as in Windows, we miss IPV6_HDRINCL for SOL_IPV6 and SOL_RAW.
The SOL_IP/IP_HDRINCL is not available for IPv6 sockets.
Signed-off-by: NHannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Add the support for adding expire value to routes,  requested by
Tom Gundersen <teg@jklm.no> for systemd-networkd, and NetworkManager
wants it too.

implement it by adding the new RTNETLINK attribute RTA_EXPIRES.
Signed-off-by: NXin Long <lucien.xin@gmail.com>
Acked-by: NHannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Before this change applications monitoring FDB notifications
were not able to determine whether a new FDB entry is permament
or not:
bridge fdb add f1:f2:f3:f4:f5:f8 dev sw0p1 temp self
bridge fdb add f1:f2:f3:f4:f5:f9 dev sw0p1 self

bridge monitor fdb

f1:f2:f3:f4:f5:f8 dev sw0p1 self permanent
f1:f2:f3:f4:f5:f9 dev sw0p1 self permanent

With this change ndm_state from the original netlink message
is passed to the new netlink message sent as notification.

bridge fdb add f1:f2:f3:f4:f5:f6 dev sw0p1 self
bridge fdb add f1:f2:f3:f4:f5:f7 dev sw0p1 temp self

bridge monitor fdb
f1:f2:f3:f4:f5:f6 dev sw0p1 self permanent
f1:f2:f3:f4:f5:f7 dev sw0p1 self static
Signed-off-by: NHubert Sokolowski <hubert.sokolowski@intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Antonio Quartulli says:

====================
Included changes:
- change my email in MAINTAINERS and Doc files
- create and export list of single hop neighs per interface
- protect CRC in the BLA code by means of its own lock
- minor fixes and code cleanups
====================
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Anjali Singhai Jain says:

====================
Add support for Geneve udp port offload

This patch series adds new ndo ops for Geneve add/del port, so as
to help offload Geneve tunnel functionalities such as RX checksum,
RSS, filters etc.

i40e driver has been tested with the changes to make sure the offloads
happen.

We do understand that this is not the ideal solution and most likely
will be redone with a more generic offload framework.
But this certainly will enable us to start seeing benefits of the
accelerations for Geneve tunnels.

As a side note, we did find an existing issue in i40e driver where a
service task can modify tunnel data structures with no locks held to
help linearize access. A separate patch will be taking care of that issue.

A question out to the community is regarding the driver Kconfig parameters
for VxLAN and Geneve, it would be ideal to drop those if there is a way
to help resolve vxlan/geneve_get_rx_port symbols while the tunnel modules
are not loaded.

Performance numbers:
With the offloads enable on X722 devices with remote checksum enabled
and no other tuning in terms of cpu governer etc on my test machine:

With offload
Throughput: 5527Mbits/sec with a single thread
%cpu: ~43% per core with 4 threads

Without offload
Throughput: 2364Mbits/sec with a single thread
%cpu: ~99% per core with 4 threads

These numbers will get better for X722 as it is being worked. But
this does bring out the delta in terms of when the stack is notified
with csum_level 1 and CHECKSUM_UNNECESSARY vs not without the RX offload.
====================
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This patch adds a call to geneve_get_rx_port in i40e so that when it
comes up it can learn about the existing geneve tunnels.
Signed-off-by: NAnjali Singhai Jain <anjali.singhai@intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This patch adds an op that the drivers can call into to get existing
geneve ports.
Signed-off-by: NAnjali Singhai Jain <anjali.singhai@intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Update the Kconfig file with dependency for supporting GENEVE tunnel
offloads.
Signed-off-by: NAnjali Singhai Jain <anjali.singhai@intel.com>
Signed-off-by: NKiran Patil <kiran.patil@intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This patch adds driver hooks to implement ndo_ops to add/del
udp port in the HW to identify GENEVE tunnels.
Signed-off-by: NAnjali Singhai Jain <anjali.singhai@intel.com>
Signed-off-by: NKiran Patil <kiran.patil@intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Add ndo_ops to add/del UDP ports to a device that supports geneve
offload.

v2: Comment fix.
Signed-off-by: NAnjali Singhai Jain <anjali.singhai@intel.com>
Signed-off-by: NKiran Patil <kiran.patil@intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

As we all know, the value of pf_retrans >= max_retrans_path can
disable pf state. The variables of pf_retrans and max_retrans_path
can be changed by the userspace application.

Sometimes the user expects to disable pf state while the 2
variables are changed to enable pf state. So it is necessary to
introduce a new variable to disable pf state.

According to the suggestions from Vlad Yasevich, extra1 and extra2
are removed. The initialization of pf_enable is added.
Acked-by: NVlad Yasevich <vyasevich@gmail.com>
Signed-off-by: NZhu Yanjun <zyjzyj2000@gmail.com>
Acked-by: NMarcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

We have found some networks in which nodes were constantly requesting
other nodes BLA claim tables to synchronize, just to ask for that again
once completed. The reason was that the crc checksum of the asked nodes
were out of sync due to missing locking and multiple writes to the same
crc checksum when adding/removing entries. Therefore the asked nodes
constantly reported the wrong crc, which caused repeating requests.

To avoid multiple functions changing a backbone gateways crc entry at
the same time, lock it using a spinlock.
Signed-off-by: NSimon Wunderlich <sw@simonwunderlich.de>
Tested-by: NAlfons Name <AlfonsName@web.de>
Signed-off-by: NMarek Lindner <mareklindner@neomailbox.ch>
Signed-off-by: NAntonio Quartulli <antonio@meshcoding.com>

Signed-off-by: NSven Eckelmann <sven@narfation.org>
Signed-off-by: NMarek Lindner <mareklindner@neomailbox.ch>
Signed-off-by: NAntonio Quartulli <antonio@meshcoding.com>

The chain pointer was already created in batadv_frag_purge_orig to make the
checks more readable. Just use the chain pointer everywhere instead of
having the same dereference + array access in the most lines of this
function.
Signed-off-by: NSven Eckelmann <sven@narfation.org>
Acked-by: NMartin Hundebøll <martin@hundeboll.net>
Signed-off-by: NMarek Lindner <mareklindner@neomailbox.ch>
Signed-off-by: NAntonio Quartulli <antonio@meshcoding.com>

This should slightly improve readability
Signed-off-by: NSimon Wunderlich <sw@simonwunderlich.de>
Signed-off-by: NMarek Lindner <mareklindner@neomailbox.ch>
Signed-off-by: NAntonio Quartulli <antonio@meshcoding.com>

If the local representation of the global TT table of one originator has
more VLAN entries than the respective TT update, there is some
inconsistency present. By detecting and reporting this inconsistency,
the global table gets updated and the excess VLAN will get removed in
the process.
Reported-by: NAlessandro Bolletta <alessandro@mediaspot.net>
Signed-off-by: NSimon Wunderlich <sw@simonwunderlich.de>
Acked-by: NAntonio Quartulli <antonio@meshcoding.com>
Signed-off-by: NMarek Lindner <mareklindner@neomailbox.ch>
Signed-off-by: NAntonio Quartulli <antonio@meshcoding.com>

modules init functions being called from process context, we better
use GFP_KERNEL allocations to increase our chances to get these
high-order pages we want for SCTP hash tables.

This mostly matters if SCTP module is loaded once memory got fragmented.
Signed-off-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Lorenzo Colitti says:

====================
Support administratively closing application sockets

This patchset adds the ability to administratively close a socket
without any action from the process owning the socket or the
socket protocol.

It implements this by adding a new diag_destroy function pointer
to struct proto. In-kernel callers can access this functionality
directly by calling sk->sk_prot->diag_destroy(sk, err).

It also exposes this functionality to userspace via a new
SOCK_DESTROY operation in the NETLINK_SOCK_DIAG sockets. This
allows a privileged userspace process, such as a connection
manager or system administration tool, to close sockets belonging
to other apps when the network they were established on has
disconnected. It is needed on laptops and mobile hosts to ensure
that network switches / disconnects do not result in applications
being blocked for long periods of time (minutes) in read or
connect calls on TCP sockets that will never succeed because the
IP address they are bound to is no longer on the system. Closing
the sockets causes these calls to fail fast and allows the apps
to reconnect on another network.

Userspace intervention is necessary because in many cases the
kernel does not have enough information to know that a connection
is now inoperable. The kernel can know if a packet can't be
routed, but in general it won't know if a TCP connection is stuck
because it is now routed to a network where its source address is
no longer valid [5][6].

Many other operating systems offer similar functionality:

 - FreeBSD has had this since 5.4 in 2005 [2]. It is available
   to privileged userspace and there is a tool to use it [3].
 - The FreeBSD commit description states that the idea came
   from OpenBSD.
 - iOS has been administratively closing app sockets since
   iOS 4 - see [4], which states that a socket "might get
   reclaimed by the kernel" and after that will return EBADF].
   For many years Android kernels have supported this via an
   out-of-tree SIOCKILLADDR ioctl that is called on every
   RTM_DELADDR event, but this solution is cleaner, more robust
   and more flexible: the connection manager can iterate over all
   connections on the deleted IP address and close all of them.
   It can also be used to close all sockets opened by a given app
   process, for example if the user has restricted that app from
   using the network, if a secure network such as a VPN has
   connected and security policy requires all of an application's
   connections to be routed via the VPN, etc.
 - For many years Android kernels have supported an out-of-tree
   SIOCKILLADDR ioctl that is called when a network disconnects
   or an RTM_DELADDR event is received. This solution is cleaner,
   more robust and more flexible. The connection manager can
   implement SIOCKILLADDR by iterating over all connections on
   the deleted IP address and close all of them, but it can also
   close all sockets opened by a given app process (for example
   if the user has restricted that app from), close all of a
   user's TCP connections if a user has connected a secure
   network such as a VPN and expects all of an application's
   connections to be routed via the VPN, etc.

Alternative schemes such as TCP keepalives in combination with
"iptables -j REJECT --reject-with tcp-reset", could be used to
achieve similar results, but on mobile devices TCP keepalives are
very expensive, and in such a scheme detecting stuck connections
has to wait for a keepalive to be sent or the application to
perform a write. An explicit notification from userspace is
cheaper and faster in the common case where an application is
blocked on read.

SOCK_DESTROY is placed behind an INET_DIAG_DESTROY configuration
option, which is currently off by default.

The TCP implementation of diag_destroy causes a TCP ABORT as
specified by RFC 793 [1]: immediately send a RST and clear local
connection state. This is what happens today if an application
enables SO_LINGER with a timeout of 0 and then calls close.

The first versions of the patchset did not send a RST, but that
is not graceful/correct TCP behaviour. tcp_abort now does a
proper RFC 793 ABORT and sends a RST to the peer. This is
consistent with BSD's tcpdrop, and is more correct in general,
even though in many use cases tcp_abort will only be called when
sending a RST is no longer possible (e.g., the network has
disconnected).

The original patchset also behaved like SIOCKILADDR and closed
TCP sockets with ETIMEDOUT. Tom Herbert pointed out that it would
be better if applications could distinguish between a timeout and
an administrative close. ECONNABORTED was chosen because it is
consistent with BSD.

[1] http://tools.ietf.org/html/rfc793#page-50
[2] http://svnweb.freebsd.org/base?view=revision&revision=141381
[3] https://www.freebsd.org/cgi/man.cgi?query=tcpdrop&sektion=8&manpath=FreeBSD+5.4-RELEASE
[4] https://developer.apple.com/library/ios/technotes/tn2277/_index.html#//apple_ref/doc/uid/DTS40010841-CH1-SUBSECTION3
[5] http://www.spinics.net/lists/netdev/msg352775.html
[6] http://www.spinics.net/lists/netdev/msg352952.html
====================
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This implements SOCK_DESTROY for TCP sockets. It causes all
blocking calls on the socket to fail fast with ECONNABORTED and
causes a protocol close of the socket. It informs the other end
of the connection by sending a RST, i.e., initiating a TCP ABORT
as per RFC 793. ECONNABORTED was chosen for consistency with
FreeBSD.
Signed-off-by: NLorenzo Colitti <lorenzo@google.com>
Acked-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This passes the SOCK_DESTROY operation to the underlying protocol
diag handler, or returns -EOPNOTSUPP if that handler does not
define a destroy operation.

Most of this patch is just renaming functions. This is not
strictly necessary, but it would be fairly counterintuitive to
have the code to destroy inet sockets be in a function whose name
starts with inet_diag_get.
Signed-off-by: NLorenzo Colitti <lorenzo@google.com>
Acked-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This patch adds a SOCK_DESTROY operation, a destroy function
pointer to sock_diag_handler, and a diag_destroy function
pointer.  It does not include any implementation code.
Signed-off-by: NLorenzo Colitti <lorenzo@google.com>
Acked-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Currently, inet_diag_dump_one_icsk finds a socket and then dumps
its information to userspace. Split it into a part that finds the
socket and a part that dumps the information.
Signed-off-by: NLorenzo Colitti <lorenzo@google.com>
Acked-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Tom Herbert says:

====================
ila: Optimization to preserve value of early demux

In the current implementation of ILA, LWT is used to perform
translation on both the input and output paths. This is functional,
however there is a big performance hit in the receive path. Early
demux occurs before the routing lookup (a hit actually obviates the
route lookup). Therefore the stack currently performs early
demux before translation so that a local connection with ILA
addresses is never matched. Note that this issue is not just
with ILA, but pretty much any translated or encapsulated packet
handled by LWT would miss the opportunity for early demux. Solving
the general problem seems non trivial since we would need to move
the route lookup before early demx thereby mitigating the value.

This patch set addresses the issue for ILA by adding a fast locator
lookup that occurs before early demux. This done by hooking in to
NF_INET_PRE_ROUTING

For the backend we implement an rhashtable that contains identifier
to locator to mappings. The table also allows more specific matches
that include original locator and interface.

This patch set:
 - Add an rhashtable function to atomically replace and element.
   This is useful to implement sub-trees from a table entry
   without needing to use a special anchor structure as the
   table entry.
 - Add a start callback for starting a netlink dump.
 - Creates an ila directory under net/ipv6 and moves ila.c to it.
   ila.c is split into ila_common.c and ila_lwt.c.
 - Implement a table to do identifier->locator mapping. This is
   an rhashtable (in ila_xlat.c).
 - Configuration for the table with netlink.
 - Add a hook into NF_INET_PRE_ROUTING to perform ILA translation
   before early demux.

Changes in v2:
 - Use iptables targets instead of a new xfrm function

Changes in v3:
 - Add __rcu to next pointer in struct ila_map

Changes in v4:
 - Use hook for NF_INET_PRE_ROUTING

Changed in v5:
 - Register hooks per namespace using nf_register_net_hooks
 - Only register hooks when first mapping is actually added

Changed in v6:
  - Remove gfp argument in alloc_ila_locks, it is unnecessary
  - Set registered_hooks properly when hooks are registered

Testing:
   Running 200 netperf TCP_RR streams

No ILA, baseline
   79.26% CPU utilization
   1678282 tps
   104/189/390 50/90/99% latencies

ILA before fix (LWT on both input and output)
   81.91% CPU utilization
   1464723 tps (-14.5% from baseline)
   121/215/411 50/90/99% latencies

ILA after fix
   80.62% CPU utilization
   1622985 (-3.4% from baseline)
   110/191/347 50/90/99% latencies
====================
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This patch implements an ILA tanslation table. This table can be
configured with identifier to locator mappings, and can be be queried
to resolve a mapping. Queries can be parameterized based on interface,
direction (incoming or outoing), and matching locator.  The table is
implemented using rhashtable and is configured via netlink (through
"ip ila .." in iproute).

The table may be used as alternative means to do do ILA tanslations
other than the lw tunnels
Signed-off-by: NTom Herbert <tom@herbertland.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The start callback allows the caller to set up a context for the
dump callbacks. Presumably, the context can then be destroyed in
the done callback.
Signed-off-by: NTom Herbert <tom@herbertland.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Add the rhashtable_replace_fast function. This replaces one object in
the table with another atomically. The hashes of the new and old objects
must be equal.
Signed-off-by: NTom Herbert <tom@herbertland.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Create ila directory in preparation for supporting other hooks in the
kernel than LWT for doing ILA. This includes:
  - Moving ila.c to ila/ila_lwt.c
  - Splitting out some common functions into ila_common.c
Signed-off-by: NTom Herbert <tom@herbertland.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Merge branch 'stmmac-mdio-compat'

Phil Reid says:

====================
stmmac: create of compatible mdio bus for stmacc driver

Provide ability to specify a fixed phy in the device tree and
retain the mdio bus if no phy is found. This is needed where
a dsa is connected via a fixed phy and uses the mdio bus for config.
Fixed ptp ref clock calculatins for the stmmac when ptp ref clock
is running at <= 50Mhz. Also add device tree setting to config
ptp clk source on socfpga platforms.

Changes from V5:
- Restore behaviour of unregister mdio bus when no phys found
  if there is no device tree node create the bus.
- Modify condition to allocate mdio_base_data conditional
  on fixed phy presece as well. Maintains existing behaviour
  in conditions where a fixed phy is not present.

Changes from V4:
- Restore #ifdef CONFIG_OF around setting of reset_gpio.
  Member doesn't exist when this isn't defined.

Changes from V3:
- Use if (IS_ENABLED(CONFIG_OF)) instead of #if.
  Reorder some code to reduce if statements.
- of_mdiobus_register already falls back to mdiobus_register
- Tested on system with CONFIG_OF

Changes from V2:
- Formatting, spaces & lines > 80 chars. Using checkpatch
- Drop PTP register debugfs patch.

Changes from V1:
- Fixed mismatch doc / code for ptp_ref_clk dt node.
- Remove unit address from doc example.
====================
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Provides an options to use the ptp clock routed from the Altera FPGA
fabric. Instead of the defalt eosc1 clock connected to the ARM HPS core.
This setting affects all emacs in the core as the ptp clock is common.
Acked-by: NRob Herring <robh@kernel.org>
Signed-off-by: NPhil Reid <preid@electromag.com.au>
Acked-by: NDinh Nguyen <dinguyen@opensource.altera.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

stmmac_config_sub_second_increment set the sub second increment to 20ns.
Driver is configured to use the fine adjustment method where the sub second
register is incremented when the acculumator incremented by the addend
register wraps overflows. This accumulator is update on every ptp clk
cycle. If a ptp clk with a period of greater than 20ns was used the
sub second register would not get updated correctly.

Instead set the sub sec increment to twice the period of the ptp clk.
This result in the addend register being set mid range and overflow
the accumlator every 2 clock cycles.
Signed-off-by: NPhil Reid <preid@electromag.com.au>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

devm_get_clk looks in clock-name property for matching clock.
the ptp_ref_clk property is ignored.
Acked-by: NRob Herring <robh@kernel.org>
Signed-off-by: NPhil Reid <preid@electromag.com.au>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The DSA driver needs to be passed a reference to an mdio bus. Typically
the mac is configured to use a fixed link but the mdio bus still needs
to be registered so that it con configure the switch.
This patch follows the same process as the altera tse ethernet driver for
creation of the mdio bus.
Acked-by: NRob Herring <robh@kernel.org>
Signed-off-by: NPhil Reid <preid@electromag.com.au>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Tom Herbert says:

====================
net: The beginning of the end for NETIF_F_IP_CSUM and NETIF_F_IPV6_CSUM

Background:

This patch set starts to address one front in the battle against
protocol ossification. Protocol ossification describes the state
that we have arrived at in the evolution of the Internet where we are
materially limited to only using a very narrow range of protocols
and protocol features. For instance, only TCP and UDP is sufficiently
supported on the Internet so that deploying alternative protocols,
such as SCTP and DCCP, are non-starters. Similarly, IP options and IPv6
extension headers are typically not considered feasible for wide
deployment, so we have loss the extensibility of IP protocols.

Protocol ossification is not only a problem on the Internet, but in
the data center as well. A root cause of this seems to be narrow,
protocol specific optimizations implemented in switches (for doing
EMCP) and in NICs (NIC offloads). These tend to be performance
optimization around TCP and UDP packets, and these have become
requirements to implement performant network solutions at scale.

Attempts to deal with protocol ossification in data center have yielded
ad hoc, sub-optimal solutions. A main driver of foo-over-UDP (e.g.
GRE/UDP, MPLS/UDP) is to leverage the existing EMCP and RSS support for
UDP by setting the source port as an entropy value. This has seen some
success, but the cost of additional overhead and layering limits its
usefulness.  An even more extreme solution is STT where non-TCP packets
are spoofed as TCP to leverage NIC offloads.

This patch set endeavours to address protocol ossification caused by
techniques used in transmit checksum offload for NICs. Future work
will address protocol ossification in the other primary NIC offloads--
namely receive checksum offload, LSO, LRO, and RSS.

NETIF_F_IP_CSUM and NETIF_F_IPV6_CSUM:

NETIF_F_IP_CSUM and NETIF_F_IPV6_CSUM exemplify the problem of protocol
ossification. These features are relics from a simpler time in the
Internet, before encapsulation, before GRE and  IPIP. Many hardware
vendors only saw the need to provide checksum offload for simple UDP and
TCP packets over IPv4 (IPv6 support is an afterthought also). In today's
Internet and data centers, checksum offload is well established as a
valuable feature, but we can no longer afford to be contsrained to
use a handful of protocols and features that are supported at the
discretion of NIC vendors. Generic and protocol agnostic methods are
needed.

The actual interface that the stack uses with drivers for checksum
offload is CHECKSUM_PARTIAL. This is a generic and protocol agnostic
interface. A driver for a device that supports this generic
interface advertises NETIF_F_HW_CSUM.

Goals of this patch set:

We propose that drivers advertise NETIF_F_HW_CSUM instead of protocol
specific values of NETIF_F_IP_CSUM and NETIF_F_IPV6_CSUM.  If the
driver's device is constrained (for instance it can only offlaod simple
IPv4 and IPv6 packets) then these constraints can be checked in the
transmit path and skb_checksum_help would be called for packets that the
driver is unable to offload. In order to facilitate this, we add some
helper functions that takes a specification argument indicating the
type of packets a device is able to offload. If a packet does not match
the specification, the helper function calls skb_checksum_help.

Benefits of this approach are:
  - Simplify the stack and clarify the interface for checksum offload
  - Encourage NIC vendors to implement the generic. protocol agnostic
    checksum offload methods in hardware
  - Encourage feature parity in NIC offloads for IPv4 and IPv6

Many drivers advertise NETIF_F_IP_CSUM and NETIF_F_IPV6_CSUM and it
probably isn't feasible to convert them all in a given time frame
(although if we could this would be a great simplification to the
stack). A reasonable direction may be to declare that new drivers must
use NETIF_F_HW_CSUM as NETIF_F_IP_CSUM and NETIF_F_IPV6_CSUM are
considered deprecated.

There is a class of drivers that should now be converted to advertise
NETIF_F_HW_CSUM, namely those that support offload of ecapsulated
checksums. These drivers have to date been using skb->encapsulation
to infer that checksum offload is being performed for an encapsulated
checksum. This is strictly not correct. skb->encapsulation
indicates that the inner headers are valid in the skbuff, whereas
the stack indicates checksum offload arguments exclusively in csum_start
and csum_offset. At some point we may want to set the inner headers for
an skbuff but offload the outer transport checksum, so this needs to be
fixed.

In this patch set:

  - Rename some of constants involved in checksum offload to be more
    reflective of their function
  - Eliminate NETIF_F_GEN_CSUM and NETIF_F_V[46]_CSUM entirely as
    unnecessary convolutions
  - Fix conditions in tcp_sendpage and tcp_sendmsg to take IP protocol
    into account when determining if checksum offload can be done
  - Add driver helper functions for determining if a checksum can
    be offloaded to a device. If not, the helper function can call
    skb_checksum_help
  - Document the checksum offload interface between the stack and
    drivers with detail and specifics

Testing:

Have been testing ixgbe and mlx4. No noticeable regressions seen yet.
====================
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Add specifics and details the description of the interface between
the stack and drivers for doing checksum offload. This description
is meant to be as specific and complete as possible.
Signed-off-by: NTom Herbert <tom@herbertland.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Add skb_csum_offload_chk driver helper function to determine if a
device with limited checksum offload capabilities is able to offload the
checksum for a given packet.

This patch includes:
  - The skb_csum_offload_chk function. Returns true if checksum is
    offloadable, else false. Optionally, in the case that the checksum
    is not offloable, the function can call skb_checksum_help to resolve
    the checksum. skb_csum_offload_chk also returns whether the checksum
    refers to an encapsulated checksum.
  - Definition of skb_csum_offl_spec structure that caller uses to
    indicate rules about what it can offload (e.g. IPv4/v6, TCP/UDP only,
    whether encapsulated checksums can be offloaded, whether checksum with
    IPv6 extension headers can be offloaded).
  - Ancilary functions called skb_csum_offload_chk_help,
    skb_csum_off_chk_help_cmn, skb_csum_off_chk_help_cmn_v4_only.
Signed-off-by: NTom Herbert <tom@herbertland.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

In tcp_send_sendpage and tcp_sendmsg we check the route capabilities to
determine if checksum offload can be performed. This check currently
does not take the IP protocol into account for devices that advertise
only one of NETIF_F_IPV6_CSUM or NETIF_F_IP_CSUM. This patch adds a
function to check capabilities for checksum offload with a socket
called sk_check_csum_caps. This function checks for specific IPv4 or
IPv6 offload support based on the family of the socket.
Signed-off-by: NTom Herbert <tom@herbertland.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

These netif flags are unnecessary convolutions. It is more
straightforward to just use NETIF_F_HW_CSUM, NETIF_F_IP_CSUM,
and NETIF_F_IPV6_CSUM directly.

This patch also:
    - Cleans up can_checksum_protocol
    - Simplifies netdev_intersect_features
Signed-off-by: NTom Herbert <tom@herbertland.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>