If the peer device was already unbound, then do not attempt to modify
it's resources, otherwise we will crash on dereferencing non-existing
device.

Fixes: 5c65c564 ("net/mlx5e: Support offloading TC NIC hairpin flows")
Signed-off-by: NAlaa Hleihel <alaa@mellanox.com>
Reviewed-by: NOr Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: NSaeed Mahameed <saeedm@mellanox.com>

Fix a simple typo: attribuets -> attributes
Signed-off-by: NJohannes Berg <johannes.berg@intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Disable the clk during suspend to save power. Note that tp->clk may be
NULL, the clk core functions handle this without problems.
Reviewed-by: NAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Tested-by: NCarlo Caione <carlo@endlessm.com>
Signed-off-by: NHans de Goede <hdegoede@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

In regular NIC transmission flow, driver always configures MAC using
Tx queue zero descriptor as a part of MAC learning flow.
But with multi Tx queue supported NIC, regular transmission can occur on
any non-zero Tx queue and from that context it uses
Tx queue zero descriptor to configure MAC, at the same time TX queue
zero could be used by another CPU for regular transmission
which could lead to Tx queue zero descriptor corruption and cause FW
abort.

This patch fixes this in such a way that driver always configures
learned MAC address from the same Tx queue which is used for
regular transmission.

Fixes: 7e2cf4fe ("qlcnic: change driver hardware interface mechanism")
Signed-off-by: NShahed Shaikh <shahed.shaikh@cavium.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

We see the following scenario:
1) Link endpoint B on node 1 discovers that its peer endpoint is gone.
   Since there is a second working link, failover procedure is started.
2) Link endpoint A on node 1 sends a FAILOVER message to peer endpoint
   A on node 2. The node item 1->2 goes to state FAILINGOVER.
3) Linke endpoint A/2 receives the failover, and is supposed to take
   down its parallell link endpoint B/2, while producing a FAILOVER
   message to send back to A/1.
4) However, B/2 has already been deleted, so no FAILOVER message can
   created.
5) Node 1->2 remains in state FAILINGOVER forever, refusing to receive
   any messages that can bring B/1 up again. We are left with a non-
   redundant link between node 1 and 2.

We fix this with letting endpoint A/2 build a dummy FAILOVER message
to send to back to A/1, so that the situation can be resolved.
Signed-off-by: NLUU Duc Canh <canh.d.luu@dektech.com.au>
Signed-off-by: NJon Maloy <jon.maloy@ericsson.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Florian Fainelli says:

====================
net: usb: Check for Wake-on-LAN modes

Most of our USB Ethernet drivers don't seem to be checking properly
whether the user is supplying a correct Wake-on-LAN mode to enter, so
the experience as an user could be confusing, since it would generally
lead to either no wake-up, or the device not being marked for wake-up.

Please review!

Changes in v2:

- fixed lan78xx handling, thanks Woojung!
====================
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The driver does not check for Wake-on-LAN modes specified by an user,
but will conditionally set the device as wake-up enabled or not based on
that, which could be a very confusing user experience.

Fixes: e0e474a8 ("smsc95xx: add wol magic packet support")
Signed-off-by: NFlorian Fainelli <f.fainelli@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The driver does not check for Wake-on-LAN modes specified by an user,
but will conditionally set the device as wake-up enabled or not based on
that, which could be a very confusing user experience.

Fixes: 6c636503 ("smsc75xx: add wol magic packet support")
Signed-off-by: NFlorian Fainelli <f.fainelli@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The driver does not check for Wake-on-LAN modes specified by an user,
but will conditionally set the device as wake-up enabled or not based on
that, which could be a very confusing user experience.

Fixes: 21ff2e89 ("r8152: support WOL")
Signed-off-by: NFlorian Fainelli <f.fainelli@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The driver currently silently accepts unsupported Wake-on-LAN modes
(other than WAKE_PHY or WAKE_MAGIC) without reporting that to the user,
which is confusing.

Fixes: 19a38d8e ("USB2NET : SR9800 : One chip USB2.0 USB2NET SR9800 Device Driver Support")
Signed-off-by: NFlorian Fainelli <f.fainelli@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The driver supports a fair amount of Wake-on-LAN modes, but is not
checking that the user specified one that is supported.

Fixes: 55d7de9d ("Microchip's LAN7800 family USB 2/3 to 10/100/1000 Ethernet device driver")
Signed-off-by: NFlorian Fainelli <f.fainelli@gmail.com>
Reviewed-by: NWoojung Huh <Woojung.Huh@Microchip.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The driver currently silently accepts unsupported Wake-on-LAN modes
(other than WAKE_PHY or WAKE_MAGIC) without reporting that to the user,
which is confusing.

Fixes: e2ca90c2 ("ax88179_178a: ASIX AX88179_178A USB 3.0/2.0 to gigabit ethernet adapter driver")
Signed-off-by: NFlorian Fainelli <f.fainelli@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The driver currently silently accepts unsupported Wake-on-LAN modes
(other than WAKE_PHY or WAKE_MAGIC) without reporting that to the user,
which is confusing.

Fixes: 2e55cc72 ("[PATCH] USB: usbnet (3/9) module for ASIX Ethernet adapters")
Signed-off-by: NFlorian Fainelli <f.fainelli@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Merge branch 'ieee802154-for-davem-2018-09-28' of git://git.kernel.org/pub/scm/linux/kernel/git/sschmidt/wpan

Stefan Schmidt says:

====================
pull-request: ieee802154 for net 2018-09-28

An update from ieee802154 for your *net* tree.

Some cleanup patches throughout the drivers from the Huawei tag team
Yue Haibing and Zhong Jiang.
Xue is replacing some magic numbers with defines in his mcr20a driver.
====================
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

David Howells says:

====================
rxrpc: Fixes

Here are some miscellaneous fixes for AF_RXRPC:

 (1) Remove a duplicate variable initialisation.

 (2) Fix one of the checks made when we decide to set up a new incoming
     service call in which a flag is being checked in the wrong field of
     the packet header.  This check is abstracted out into helper
     functions.

 (3) Fix RTT gathering.  The code has been trying to make use of socket
     timestamps, but wasn't actually enabling them.  The code has also been
     recording a transmit time for the outgoing packet for which we're
     going to measure the RTT after sending the message - but we can get
     the incoming packet before we get to that and record a negative RTT.

 (4) Fix the emission of BUSY packets (we are emitting ABORTs instead).

 (5) Improve error checking on incoming packets.

 (6) Try to fix a bug in new service call handling whereby a BUG we should
     never be able to reach somehow got triggered.  Do this by moving much
     of the checking as early as possible and not repeating it later
     (depends on (5) above).

 (7) Fix the sockopts set on a UDP6 socket to include the ones set on a
     UDP4 socket so that we receive UDP4 errors and packet-too-large
     notifications too.

 (8) Fix the distribution of errors so that we do it at the point of
     receiving an error in the UDP callback rather than deferring it
     thereby cutting short any transmissions that would otherwise occur in
     the window.
====================
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Eric Dumazet says:

====================
netpoll: second round of fixes.

As diagnosed by Song Liu, ndo_poll_controller() can
be very dangerous on loaded hosts, since the cpu
calling ndo_poll_controller() might steal all NAPI
contexts (for all RX/TX queues of the NIC).

This capture, showing one ksoftirqd eating all cycles
can last for unlimited amount of time, since one
cpu is generally not able to drain all the queues under load.

It seems that all networking drivers that do use NAPI
for their TX completions, should not provide a ndo_poll_controller() :

Most NAPI drivers have netpoll support already handled
in core networking stack, since netpoll_poll_dev()
uses poll_napi(dev) to iterate through registered
NAPI contexts for a device.

First patch is a fix in poll_one_napi().

Then following patches take care of ten drivers.
====================
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

As diagnosed by Song Liu, ndo_poll_controller() can
be very dangerous on loaded hosts, since the cpu
calling ndo_poll_controller() might steal all NAPI
contexts (for all RX/TX queues of the NIC). This capture
can last for unlimited amount of time, since one
cpu is generally not able to drain all the queues under load.

ibmvnic uses NAPI for TX completions, so we better let core
networking stack call the napi->poll() to avoid the capture.

ibmvnic_netpoll_controller() was completely wrong anyway,
as it was scheduling NAPI to service RX queues (instead of TX),
so I doubt netpoll ever worked on this driver.
Signed-off-by: NEric Dumazet <edumazet@google.com>
Cc: Thomas Falcon <tlfalcon@linux.vnet.ibm.com>
Cc: John Allen <jallen@linux.vnet.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

As diagnosed by Song Liu, ndo_poll_controller() can
be very dangerous on loaded hosts, since the cpu
calling ndo_poll_controller() might steal all NAPI
contexts (for all RX/TX queues of the NIC). This capture
can last for unlimited amount of time, since one
cpu is generally not able to drain all the queues under load.

sfc-falcon uses NAPI for TX completions, so we better let core
networking stack call the napi->poll() to avoid the capture.
Signed-off-by: NEric Dumazet <edumazet@google.com>
Cc: Solarflare linux maintainers <linux-net-drivers@solarflare.com>
Cc: Edward Cree <ecree@solarflare.com>
Cc: Bert Kenward <bkenward@solarflare.com>
Acked-By: NBert Kenward <bkenward@solarflare.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

As diagnosed by Song Liu, ndo_poll_controller() can
be very dangerous on loaded hosts, since the cpu
calling ndo_poll_controller() might steal all NAPI
contexts (for all RX/TX queues of the NIC). This capture
can last for unlimited amount of time, since one
cpu is generally not able to drain all the queues under load.

sfc uses NAPI for TX completions, so we better let core
networking stack call the napi->poll() to avoid the capture.
Signed-off-by: NEric Dumazet <edumazet@google.com>
Cc: Edward Cree <ecree@solarflare.com>
Cc: Bert Kenward <bkenward@solarflare.com>
Cc: Solarflare linux maintainers <linux-net-drivers@solarflare.com>
Acked-By: NBert Kenward <bkenward@solarflare.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

As diagnosed by Song Liu, ndo_poll_controller() can
be very dangerous on loaded hosts, since the cpu
calling ndo_poll_controller() might steal all NAPI
contexts (for all RX/TX queues of the NIC). This capture
can last for unlimited amount of time, since one
cpu is generally not able to drain all the queues under load.

ena uses NAPI for TX completions, so we better let core
networking stack call the napi->poll() to avoid the capture.
Signed-off-by: NEric Dumazet <edumazet@google.com>
Cc: Netanel Belgazal <netanel@amazon.com>
Cc: Saeed Bishara <saeedb@amazon.com>
Cc: Zorik Machulsky <zorik@amazon.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

As diagnosed by Song Liu, ndo_poll_controller() can
be very dangerous on loaded hosts, since the cpu
calling ndo_poll_controller() might steal all NAPI
contexts (for all RX/TX queues of the NIC). This capture
can last for unlimited amount of time, since one
cpu is generally not able to drain all the queues under load.

netxen uses NAPI for TX completions, so we better let core
networking stack call the napi->poll() to avoid the capture.
Signed-off-by: NEric Dumazet <edumazet@google.com>
Cc: Manish Chopra <manish.chopra@cavium.com>
Cc: Rahul Verma <rahul.verma@cavium.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

As diagnosed by Song Liu, ndo_poll_controller() can
be very dangerous on loaded hosts, since the cpu
calling ndo_poll_controller() might steal all NAPI
contexts (for all RX/TX queues of the NIC). This capture
can last for unlimited amount of time, since one
cpu is generally not able to drain all the queues under load.

qlcnic uses NAPI for TX completions, so we better let core
networking stack call the napi->poll() to avoid the capture.
Signed-off-by: NEric Dumazet <edumazet@google.com>
Cc: Harish Patil <harish.patil@cavium.com>
Cc: Manish Chopra <manish.chopra@cavium.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

As diagnosed by Song Liu, ndo_poll_controller() can
be very dangerous on loaded hosts, since the cpu
calling ndo_poll_controller() might steal all NAPI
contexts (for all RX/TX queues of the NIC). This capture
can last for unlimited amount of time, since one
cpu is generally not able to drain all the queues under load.

virto_net uses NAPI for TX completions, so we better let core
networking stack call the napi->poll() to avoid the capture.
Signed-off-by: NEric Dumazet <edumazet@google.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Jason Wang <jasowang@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

As diagnosed by Song Liu, ndo_poll_controller() can
be very dangerous on loaded hosts, since the cpu
calling ndo_poll_controller() might steal all NAPI
contexts (for all RX/TX queues of the NIC). This capture
can last for unlimited amount of time, since one
cpu is generally not able to drain all the queues under load.

hns uses NAPI for TX completions, so we better let core
networking stack call the napi->poll() to avoid the capture.
Signed-off-by: NEric Dumazet <edumazet@google.com>
Cc: Yisen Zhuang <yisen.zhuang@huawei.com>
Cc: Salil Mehta <salil.mehta@huawei.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

As diagnosed by Song Liu, ndo_poll_controller() can
be very dangerous on loaded hosts, since the cpu
calling ndo_poll_controller() might steal all NAPI
contexts (for all RX/TX queues of the NIC). This capture
can last for unlimited amount of time, since one
cpu is generally not able to drain all the queues under load.

ehea uses NAPI for TX completions, so we better let core
networking stack call the napi->poll() to avoid the capture.
Signed-off-by: NEric Dumazet <edumazet@google.com>
Cc: Douglas Miller <dougmill@linux.vnet.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

As diagnosed by Song Liu, ndo_poll_controller() can
be very dangerous on loaded hosts, since the cpu
calling ndo_poll_controller() might steal all NAPI
contexts (for all RX/TX queues of the NIC). This capture
can last for unlimited amount of time, since one
cpu is generally not able to drain all the queues under load.

hinic uses NAPI for TX completions, so we better let core
networking stack call the napi->poll() to avoid the capture.

Note that hinic_netpoll() was incorrectly scheduling NAPI
on both RX and TX queues.
Signed-off-by: NEric Dumazet <edumazet@google.com>
Cc: Aviad Krawczyk <aviad.krawczyk@huawei.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Since we do no longer require NAPI drivers to provide
an ndo_poll_controller(), napi_schedule() has not been done
before poll_one_napi() invocation.

So testing NAPI_STATE_SCHED is likely to cause early returns.

While we are at it, remove outdated comment.

Note to future bisections : This change might surface prior
bugs in drivers. See commit 73f21c65 ("bnxt_en: Fix TX
timeout during netpoll.") for one occurrence.

Fixes: ac3d9dd0 ("netpoll: make ndo_poll_controller() optional")
Signed-off-by: NEric Dumazet <edumazet@google.com>
Tested-by: NSong Liu <songliubraving@fb.com>
Cc: Michael Chan <michael.chan@broadcom.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Merge tag 'mac80211-for-davem-2018-09-27' of git://git.kernel.org/pub/scm/linux/kernel/git/jberg/mac80211

Johannes Berg says:

====================
More patches than I'd like perhaps, but each seems reasonable:
 * two new spectre-v1 mitigations in nl80211
 * TX status fix in general, and mesh in particular
 * powersave vs. offchannel fix
 * regulatory initialization fix
 * fix for a queue hang due to a bad return value
 * allocate TXQs for active monitor interfaces, fixing my
   earlier patch to avoid unnecessary allocations where I
   missed this case needed them
 * fix TDLS data frames priority assignment
 * fix scan results processing to take into account duplicate
   channel numbers (over different operating classes, but we
   don't necessarily know the operating class)
 * various hwsim fixes for radio destruction and new radio
   announcement messages
 * remove an extraneous kernel-doc line
====================
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The structure shared between driver and the management FW (mfw) differ in
sizes. This would lead to issues when driver try to access the structure
members which are not-aligned with the mfw copy e.g., data_ptr usage in the
case of mfw_tlv request.
Align the driver structure with mfw copy, add reserved field(s) to driver
structure for the members not used by the driver.

Fixes: dd006921 ("qed: Add MFW interfaces for TLV request support.)
Signed-off-by: NSudarsana Reddy Kalluru <Sudarsana.Kalluru@cavium.com>
Signed-off-by: NMichal Kalderon <Michal.Kalderon@cavium.com>

Signed-off-by: NSudarsana Reddy Kalluru <Sudarsana.Kalluru@cavium.com>
Signed-off-by: NAmeen Rahman <Ameen.Rahman@cavium.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

I haven't been doing reviews only but not active development on bridge
code for several years. Roopa and Nikolay have been doing most of
the new features and have agreed to take over as new co-maintainers.
Signed-off-by: NStephen Hemminger <stephen@networkplumber.org>
Acked-by: NRoopa Prabhu <roopa@cumulusnetworks.com>
Acked-by: NNikolay Aleksandrov <nikolay@cumulusnetworks.com>

Julian Wiedmann says:

====================
s390/qeth: fixes 2019-09-26

please apply two qeth patches for -net. The first is a trivial cleanup
required for patch #2 by Jean, which fixes a potential endless loop.
====================
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Functions qeth_get_ipa_msg and qeth_get_ipa_cmd_name are modifying
the last member of global arrays without any locking that I can see.
If two instances of either function are running at the same time,
it could cause a race ultimately leading to an array overrun (the
contents of the last entry of the array is the only guarantee that
the loop will ever stop).

Performing the lookups without modifying the arrays is admittedly
slower (two comparisons per iteration instead of one) but these
are operations which are rare (should only be needed in error
cases or when debugging, not during successful operation) and it
seems still less costly than introducing a mutex to protect the
arrays in question.

As a side bonus, it allows us to declare both arrays as const data.
Signed-off-by: NJean Delvare <jdelvare@suse.de>
Cc: Julian Wiedmann <jwi@linux.ibm.com>
Cc: Ursula Braun <ubraun@linux.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: NJulian Wiedmann <jwi@linux.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Use the common code ARRAY_SIZE macro instead of a private implementation.
Reviewed-by: NJean Delvare <jdelvare@suse.de>
Signed-off-by: Nzhong jiang <zhongjiang@huawei.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: NJulian Wiedmann <jwi@linux.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Fix error distribution by immediately delivering the errors to all the
affected calls rather than deferring them to a worker thread.  The problem
with the latter is that retries and things can happen in the meantime when we
want to stop that sooner.

To this end:

 (1) Stop the error distributor from removing calls from the error_targets
     list so that peer->lock isn't needed to synchronise against other adds
     and removals.

 (2) Require the peer's error_targets list to be accessed with RCU, thereby
     avoiding the need to take peer->lock over distribution.

 (3) Don't attempt to affect a call's state if it is already marked complete.
Signed-off-by: NDavid Howells <dhowells@redhat.com>

It seems that enabling IPV6_RECVERR on an IPv6 socket doesn't also turn on
IP_RECVERR, so neither local errors nor ICMP-transported remote errors from
IPv4 peer addresses are returned to the AF_RXRPC protocol.

Make the sockopt setting code in rxrpc_open_socket() fall through from the
AF_INET6 case to the AF_INET case to turn on all the AF_INET options too in
the AF_INET6 case.

Fixes: f2aeed3a ("rxrpc: Fix error reception on AF_INET6 sockets")
Signed-off-by: NDavid Howells <dhowells@redhat.com>

Make the following changes to improve the robustness of the code that sets
up a new service call:

 (1) Cache the rxrpc_sock struct obtained in rxrpc_data_ready() to do a
     service ID check and pass that along to rxrpc_new_incoming_call().
     This means that I can remove the check from rxrpc_new_incoming_call()
     without the need to worry about the socket attached to the local
     endpoint getting replaced - which would invalidate the check.

 (2) Cache the rxrpc_peer struct, thereby allowing the peer search to be
     done once.  The peer is passed to rxrpc_new_incoming_call(), thereby
     saving the need to repeat the search.

     This also reduces the possibility of rxrpc_publish_service_conn()
     BUG()'ing due to the detection of a duplicate connection, despite the
     initial search done by rxrpc_find_connection_rcu() having turned up
     nothing.

     This BUG() shouldn't ever get hit since rxrpc_data_ready() *should* be
     non-reentrant and the result of the initial search should still hold
     true, but it has proven possible to hit.

     I *think* this may be due to __rxrpc_lookup_peer_rcu() cutting short
     the iteration over the hash table if it finds a matching peer with a
     zero usage count, but I don't know for sure since it's only ever been
     hit once that I know of.

     Another possibility is that a bug in rxrpc_data_ready() that checked
     the wrong byte in the header for the RXRPC_CLIENT_INITIATED flag
     might've let through a packet that caused a spurious and invalid call
     to be set up.  That is addressed in another patch.

 (3) Fix __rxrpc_lookup_peer_rcu() to skip peer records that have a zero
     usage count rather than stopping and returning not found, just in case
     there's another peer record behind it in the bucket.

 (4) Don't search the peer records in rxrpc_alloc_incoming_call(), but
     rather either use the peer cached in (2) or, if one wasn't found,
     preemptively install a new one.

Fixes: 8496af50 ("rxrpc: Use RCU to access a peer's service connection tree")
Signed-off-by: NDavid Howells <dhowells@redhat.com>

Do more up-front checking on incoming packets to weed out invalid ones and
also ones aimed at services that we don't support.

Whilst we're at it, replace the clearing of call and skew if we don't find
a connection with just initialising the variables to zero at the top of the
function.
Signed-off-by: NDavid Howells <dhowells@redhat.com>

In the input path, a received sk_buff can be marked for rejection by
setting RXRPC_SKB_MARK_* in skb->mark and, if needed, some auxiliary data
(such as an abort code) in skb->priority.  The rejection is handled by
queueing the sk_buff up for dealing with in process context.  The output
code reads the mark and priority and, theoretically, generates an
appropriate response packet.

However, if RXRPC_SKB_MARK_BUSY is set, this isn't noticed and an ABORT
message with a random abort code is generated (since skb->priority wasn't
set to anything).

Fix this by outputting the appropriate sort of packet.

Also, whilst we're at it, most of the marks are no longer used, so remove
them and rename the remaining two to something more obvious.

Fixes: 248f219c ("rxrpc: Rewrite the data and ack handling code")
Signed-off-by: NDavid Howells <dhowells@redhat.com>

Fix RTT information gathering in AF_RXRPC by the following means:

 (1) Enable Rx timestamping on the transport socket with SO_TIMESTAMPNS.

 (2) If the sk_buff doesn't have a timestamp set when rxrpc_data_ready()
     collects it, set it at that point.

 (3) Allow ACKs to be requested on the last packet of a client call, but
     not a service call.  We need to be careful lest we undo:

	bf7d620a
	Author: David Howells <dhowells@redhat.com>
	Date:   Thu Oct 6 08:11:51 2016 +0100
	rxrpc: Don't request an ACK on the last DATA packet of a call's Tx phase

     but that only really applies to service calls that we're handling,
     since the client side gets to send the final ACK (or not).

 (4) When about to transmit an ACK or DATA packet, record the Tx timestamp
     before only; don't update the timestamp afterwards.

 (5) Switch the ordering between recording the serial and recording the
     timestamp to always set the serial number first.  The serial number
     shouldn't be seen referenced by an ACK packet until we've transmitted
     the packet bearing it - so in the Rx path, we don't need the timestamp
     until we've checked the serial number.

Fixes: cf1a6474 ("rxrpc: Add per-peer RTT tracker")
Signed-off-by: NDavid Howells <dhowells@redhat.com>