Now ip_gre is using ip_tunnel_changelink to update it's properties, but
ip_tunnel_changelink in ip_tunnel doesn't update i/o_flags as a common
function.

o_flags updates would cause that tunnel->tun_hlen / hlen and dev->mtu /
needed_headroom need to be recalculated, and dev->(hw_)features need to
be updated as well.

Therefore, we can't just add the update into ip_tunnel_update called
in ip_tunnel_changelink, and it's also better not to touch ip_tunnel
codes.

This patch updates i/o_flags and calls ipgre_link_update to recalculate
these gre properties after ip_tunnel_changelink does the common update.

Note that since ipgre_link_update doesn't know the lower dev, it will
update gre->hlen, dev->mtu and dev->needed_headroom with the value of
'new tun_hlen - old tun_hlen'. In this way, we can avoid many redundant
codes, unlike ip6_gre.
Reported-by: NJianlin Shi <jishi@redhat.com>
Signed-off-by: NXin Long <lucien.xin@gmail.com>
Acked-by: NWilliam Tu <u9012063@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Eric Dumazet says:

====================
net: Namespace-ify sysctl_tcp_rmem and sysctl_tcp_wmem

We need to get per netns sysctl for sysctl_[proto]_rmem and sysctl_[proto]_wmem

This patch series adds the basic infrastructure allowing per proto
conversion, and takes care of TCP.
====================
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Note that when a new netns is created, it inherits its
sysctl_tcp_rmem and sysctl_tcp_wmem from initial netns.

This change is needed so that we can refine TCP rcvbuf autotuning,
to take RTT into consideration.
Signed-off-by: NEric Dumazet <edumazet@google.com>
Cc: Wei Wang <weiwan@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

As we want to gradually implement per netns sysctl_rmem and sysctl_wmem
on per protocol basis, add two new fields in struct proto,
and two new helpers : sk_get_wmem0() and sk_get_rmem0()

First user will be TCP. Then UDP and SCTP can be easily converted,
while DECNET probably wont get this support.
Signed-off-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The software bridge can be build with vlan filtering support
included. However, by default it is turned off. In its turned off
state, it still passes VLANs via switchev, even though they are not to
be used. Don't pass these VLANs to the hardware. Only do so when vlan
filtering is enabled.

This fixes at least one corner case. There are still issues in other
corners, such as when vlan_filtering is later enabled.
Signed-off-by: NAndrew Lunn <andrew@lunn.ch>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Saeed Mahameed says:

====================
mlx5-updates-2017-11-09

This series introduces vlan offloads related improvements for mlx5
ethernet netdev driver, from Gal Pressman.

 - Add support for 802.1ad vlan filter
 - Add support for 802.1ad vlan insertion
 - Add vlan offloads statistics to ethtool (inserted/stripped vlans)
 - CHECKSUM_COMPLETE support for vlan traffic when vlan stripping is off! (Finally)
====================
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Andrew Lunn says:

====================
IGMP snooping for local traffic

The linux bridge supports IGMP snooping. It will listen to IGMP
reports on bridge ports and keep track of which groups have been
joined on an interface. It will then forward multicast based on this
group membership.

When the bridge adds or removed groups from an interface, it uses
switchdev to request the hardware add an mdb to a port, so the
hardware can perform the selective forwarding between ports.

What is not covered by the current bridge code, is IGMP joins/leaves
from the host on the brX interface. These are not reported via
switchdev so that hardware knows the local host is interested in the
multicast frames.

Luckily, the bridge does track joins/leaves on the brX interface. The
code is obfusticated, which is why i missed it with my first attempt.
So the first patch tries to remove this obfustication. Currently,
there is no notifications sent when the bridge interface joins a
group. The second patch adds them. bridge monitor then shows
joins/leaves in the same way as for other ports of the bridge.

Then starts the work passing down to the hardware that the host has
joined/left a group. The existing switchdev mdb object cannot be used,
since the semantics are different. The existing
SWITCHDEV_OBJ_ID_PORT_MDB is used to indicate a specific multicast
group should be forwarded out that port of the switch. However here we
require the exact opposite. We want multicast frames for the group
received on the port to the forwarded to the host. Hence add a new
object SWITCHDEV_OBJ_ID_HOST_MDB, a multicast database entry to
forward to the host. This new object is then propagated through the
DSA layers. No DSA driver changes should be needed, this should just
work...

This version fixes up the nitpick from Nikolay, removes an unrelated
white space change, and adds in a patch adding a few const attributes
to a couple of functions taking a port parameter, in order to stop the
following patch produces warnings.
====================
Acked-by: NStephen Hemminger <stephen@networkplumber.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Now that the host indicates when a multicast group should be forwarded
from the switch to the host, don't do it by default.
Signed-off-by: NAndrew Lunn <andrew@lunn.ch>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The notify mechanism does not need to modify the port it is notifying.
So make the parameter const.
Signed-off-by: NAndrew Lunn <andrew@lunn.ch>
Reviewed-by: NVivien Didelot <vivien.didelot@savoirfairelinux.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Add code to handle switchdev host mdb add/del. Since DSA uses one of
the switch ports as a transport to the host, we just need to add an
MDB on this port.
Signed-off-by: NAndrew Lunn <andrew@lunn.ch>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

When the host joins or leaves a multicast group, use switchdev to add
an object to the hardware to forward traffic for the group to the
host.
Signed-off-by: NAndrew Lunn <andrew@lunn.ch>
Acked-by: NNikolay Aleksandrov <nikolay@cumulusnetworks.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The host can join or leave a multicast group on the brX interface, as
indicated by IGMP snooping.  This is tracked within the bridge
multicast code. Send a notification when this happens, in the same way
a notification is sent when a port of the bridge joins/leaves a group
because of IGMP snooping.
Signed-off-by: NAndrew Lunn <andrew@lunn.ch>
Acked-by: NNikolay Aleksandrov <nikolay@cumulusnetworks.com>
Acked-by: NFlorian Fainelli <f.fainelli@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The boolean mglist indicates the host has joined a particular
multicast group on the bridge interface. It is badly named, obscuring
what is means. Rename it.
Signed-off-by: NAndrew Lunn <andrew@lunn.ch>
Acked-by: NNikolay Aleksandrov <nikolay@cumulusnetworks.com>
Acked-by: NFlorian Fainelli <f.fainelli@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Simple cases of overlapping changes in the packet scheduler.

Must easier to resolve this time.

Which probably means that I screwed it up somehow.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Pull final power management fixes from Rafael Wysocki:
 "These fix a regression in the schedutil cpufreq governor introduced by
  a recent change and blacklist Dell XPS13 9360 from using the Low Power
  S0 Idle _DSM interface which triggers serious problems on one of these
  machines.

  Specifics:

   - Prevent the schedutil cpufreq governor from using the utilization
     of a wrong CPU in some cases which started to happen after one of
     the recent changes in it (Chris Redpath).

   - Blacklist Dell XPS13 9360 from using the Low Power S0 Idle _DSM
     interface as that causes serious issue (related to NVMe) to appear
     on one of these machines, even though the other Dells XPS13 9360 in
     somewhat different HW configurations behave correctly (Rafael
     Wysocki)"

* tag 'pm-final-4.14' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
  ACPI / PM: Blacklist Low Power S0 Idle _DSM for Dell XPS13 9360
  cpufreq: schedutil: Examine the correct CPU when we update util

Pull sound fixes from Takashi Iwai:
 "The amount of the changes isn't as quite small as wished, nevertheless
  they are straight fixes that deserve merging to 4.14 final.

  Most of fixes are about ALSA core bugs spotted by fuzzer: a follow-up
  fix for the previous nested rwsem patch, a fix to avoid the resource
  hogs due to too many concurrent ALSA timer invocations, and a fix for
  a crash with SYSEX MIDI transfer over OSS sequencer emulation that is
  used by none but fuzzer.

  The rest are usual HD-audio and USB-audio device-specific quirks,
  which are safe to apply"

* tag 'sound-4.14' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound:
  ALSA: hda - fix headset mic problem for Dell machines with alc274
  ALSA: seq: Fix OSS sysex delivery in OSS emulation
  ALSA: seq: Avoid invalid lockdep class warning
  ALSA: timer: Limit max instances per timer
  ALSA: usb-audio: support new Amanero Combo384 firmware version

Pull networking fixes from David Miller:

 1) Fix use-after-free in IPSEC input parsing, desintation address
    pointer was loaded before pskb_may_pull() which can change the SKB
    data pointers. From Florian Westphal.

 2) Stack out-of-bounds read in xfrm_state_find(), from Steffen
    Klassert.

 3) IPVS state of SKB is not properly reset when moving between
    namespaces, from Ye Yin.

 4) Fix crash in asix driver suspend and resume, from Andrey Konovalov.

 5) Don't deliver ipv6 l2tp tunnel packets to ipv4 l2tp tunnels, and
    vice versa, from Guillaume Nault.

 6) Fix DSACK undo on non-dup ACKs, from Priyaranjan Jha.

 7) Fix regression in bond_xmit_hash()'s behavior after the TCP port
    selection changes back in 4.2, from Hangbin Liu.

 8) Two divide by zero bugs in USB networking drivers when parsing
    descriptors, from Bjorn Mork.

 9) Fix bonding slaves being stuck in BOND_LINK_FAIL state, from Jay
    Vosburgh.

10) Missing skb_reset_mac_header() in qmi_wwan, from Kristian Evensen.

11) Fix the destruction of tc action object races properly, from Cong
    Wang.

* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net: (31 commits)
  cls_u32: use tcf_exts_get_net() before call_rcu()
  cls_tcindex: use tcf_exts_get_net() before call_rcu()
  cls_rsvp: use tcf_exts_get_net() before call_rcu()
  cls_route: use tcf_exts_get_net() before call_rcu()
  cls_matchall: use tcf_exts_get_net() before call_rcu()
  cls_fw: use tcf_exts_get_net() before call_rcu()
  cls_flower: use tcf_exts_get_net() before call_rcu()
  cls_flow: use tcf_exts_get_net() before call_rcu()
  cls_cgroup: use tcf_exts_get_net() before call_rcu()
  cls_bpf: use tcf_exts_get_net() before call_rcu()
  cls_basic: use tcf_exts_get_net() before call_rcu()
  net_sched: introduce tcf_exts_get_net() and tcf_exts_put_net()
  Revert "net_sched: hold netns refcnt for each action"
  net: usb: asix: fill null-ptr-deref in asix_suspend
  Revert "net: usb: asix: fill null-ptr-deref in asix_suspend"
  qmi_wwan: Add missing skb_reset_mac_header-call
  bonding: fix slave stuck in BOND_LINK_FAIL state
  qrtr: Move to postcore_initcall
  net: qmi_wwan: fix divide by 0 on bad descriptors
  net: cdc_ether: fix divide by 0 on bad descriptors
  ...

Confirmed with Kailang of Realtek, the pin 0x19 is for Headset Mic, and
the pin 0x1a is for Headphone Mic, he suggested to apply
ALC269_FIXUP_DELL1_MIC_NO_PRESENCE to fix this problem. And we
verified applying this FIXUP can fix this problem.

Cc: <stable@vger.kernel.org>
Cc: Kailang Yang <kailang@realtek.com>
Signed-off-by: NHui Wang <hui.wang@canonical.com>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>

When the VLAN tag is present in the packet buffer (i.e VLAN stripping disabled, QinQ)
the driver will currently report CHECKSUM_UNNECESSARY.
Instead of using CHECKSUM_COMPLETE offload for packets with first
ethertype of IPv4/6, use it for packets with last ethertype of IPv4/6 to
cover the former cases as well.

The checksum field present in the CQE is calculated from the IP header
until the end of the packet. When the first ethertype is different than
IPv4/6 (for ex. 802.1Q VLAN) a checksum of the VLAN header/s should be
added. The small header/s checksum calculation will allow us to use
CHECKSUM_COMPLETE instead of CHECKSUM_UNNECESSARY.

Testing bandwidth of one and 8 TCP streams to a single RQ,
LRO and VLAN stripping offloads disabled:
CPU: Intel(R) Xeon(R) CPU E5-2660 v2 @ 2.20GHz
NIC: Mellanox Technologies MT27710 Family [ConnectX-4 Lx]

Before:
+--------------+--------------------+---------------------+----------------------+
| Traffic type | 1 Stream BW [Mbps] | 8 Streams BW [Mbps] |   Checksum offload   |
+--------------+--------------------+---------------------+----------------------+
| Untagged     |          28,247.35 |           24,716.88 | CHECKSUM_COMPLETE    |
| VLAN         |          27,516.69 |           23,752.26 | CHECKSUM_UNNECESSARY |
| QinQ         |           6,961.30 |           20,667.04 | CHECKSUM_UNNECESSARY |
+--------------+--------------------+---------------------+----------------------+

Now:
+--------------+--------------------+---------------------+-------------------+
| Traffic type | 1 Stream BW [Mbps] | 8 Streams BW [Mbps] | Checksum offload  |
+--------------+--------------------+---------------------+-------------------+
| Untagged     |          28,521.28 |           24,926.32 | CHECKSUM_COMPLETE |
| VLAN         |          27,389.37 |           23,715.34 | CHECKSUM_COMPLETE |
| QinQ         |           6,901.77 |           20,845.73 | CHECKSUM_COMPLETE |
+--------------+--------------------+---------------------+-------------------+

No performance degradation observed.
Signed-off-by: NGal Pressman <galp@mellanox.com>
Reviewed-by: NTariq Toukan <tariqt@mellanox.com>
Signed-off-by: NSaeed Mahameed <saeedm@mellanox.com>

The following counters are now exposed through ethtool -S:
rx[i]_removed_vlan_packets (per channel)
rx_removed_vlan_packets
tx[i]_added_vlan_packets (per channel)
tx_added_vlan_packets

rx_removed_vlan_packets: The number of packets that had their
outer VLAN header stripped to the CQE by the hardware.
tx_added_vlan_packets: The number of packets that had their
outer VLAN header inserted by the hardware.
Signed-off-by: NGal Pressman <galp@mellanox.com>
Reviewed-by: NTariq Toukan <tariqt@mellanox.com>
Signed-off-by: NSaeed Mahameed <saeedm@mellanox.com>

Report VLAN insertion support for S-tagged packets and add support by
choosing the correct VLAN type in the WQE.
Signed-off-by: NGal Pressman <galp@mellanox.com>
Reviewed-by: NTariq Toukan <tariqt@mellanox.com>
Signed-off-by: NSaeed Mahameed <saeedm@mellanox.com>

When a user chooses to use 802.1ad VLAN the proper steering rules will
be added to the VLAN flow table (matching the specific S-tag VID).
Due to current hardware limitation, when using 802.1ad, we must disable
C-tag VLAN stripping on the RQs.
Signed-off-by: NGal Pressman <galp@mellanox.com>
Reviewed-by: NMaor Gottlieb <maorg@mellanox.com>
Signed-off-by: NSaeed Mahameed <saeedm@mellanox.com>

Replace explicit declaration of bitmap with DECLARE_BITMAP kernel macro.
Signed-off-by: NGal Pressman <galp@mellanox.com>
Reviewed-by: NMaor Gottlieb <maorg@mellanox.com>
Signed-off-by: NSaeed Mahameed <saeedm@mellanox.com>

Extend the net device error logging with netdev_*_once macros.
netdev_*_once are the equivalents of the dev_*_once macros which are
useful for messages that should only be logged once.

Also add netdev_WARN_ONCE, which is the "once" extension for the already
existing netdev_WARN macro.
Signed-off-by: NGal Pressman <galp@mellanox.com>
Signed-off-by: NSaeed Mahameed <saeedm@mellanox.com>

When add VLAN rule fails the active vlan bit should be cleared.

Fixes: afb736e9 ("net/mlx5: Ethernet resource handling files")
Signed-off-by: NGal Pressman <galp@mellanox.com>
Reviewed-by: NMaor Gottlieb <maorg@mellanox.com>
Signed-off-by: NSaeed Mahameed <saeedm@mellanox.com>

Rename VLAN related symbols to better reflect the fact that they
are associated to C-tag VLAN.
Signed-off-by: NGal Pressman <galp@mellanox.com>
Reviewed-by: NMaor Gottlieb <maorg@mellanox.com>
Signed-off-by: NSaeed Mahameed <saeedm@mellanox.com>

Steffen Klassert says:

====================
pull request (net): ipsec 2017-11-09

1) Fix a use after free due to a reallocated skb head.
   From Florian Westphal.

2) Fix sporadic lookup failures on labeled IPSEC.
   From Florian Westphal.

3) Fix a stack out of bounds when a socket policy is applied
   to an IPv6 socket that sends IPv4 packets.

Please pull or let me know if there are problems.
====================
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Cong Wang says:

====================
net_sched: close the race between call_rcu() and cleanup_net()

This patchset tries to fix the race between call_rcu() and
cleanup_net() again. Without holding the netns refcnt the
tc_action_net_exit() in netns workqueue could be called before
filter destroy works in tc filter workqueue. This patchset
moves the netns refcnt from tc actions to tcf_exts, without
breaking per-netns tc actions.

Patch 1 reverts the previous fix, patch 2 introduces two new
API's to help to address the bug and the rest patches switch
to the new API's. Please see each patch for details.

I was not able to reproduce this bug, but now after adding
some delay in filter destroy work I manage to trigger the
crash. After this patchset, the crash is not reproducible
any more and the debugging printk's show the order is expected
too.
====================

Fixes: ddf97ccd ("net_sched: add network namespace support for tc actions")
Reported-by: NLucas Bates <lucasb@mojatatu.com>
Cc: Lucas Bates <lucasb@mojatatu.com>
Cc: Jamal Hadi Salim <jhs@mojatatu.com>
Cc: Jiri Pirko <jiri@resnulli.us>
Signed-off-by: NCong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Hold netns refcnt before call_rcu() and release it after
the tcf_exts_destroy() is done.

Note, on ->destroy() path we have to respect the return value
of tcf_exts_get_net(), on other paths it should always return
true, so we don't need to care.

Cc: Lucas Bates <lucasb@mojatatu.com>
Cc: Jamal Hadi Salim <jhs@mojatatu.com>
Cc: Jiri Pirko <jiri@resnulli.us>
Signed-off-by: NCong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Hold netns refcnt before call_rcu() and release it after
the tcf_exts_destroy() is done.

Note, on ->destroy() path we have to respect the return value
of tcf_exts_get_net(), on other paths it should always return
true, so we don't need to care.

Cc: Lucas Bates <lucasb@mojatatu.com>
Cc: Jamal Hadi Salim <jhs@mojatatu.com>
Cc: Jiri Pirko <jiri@resnulli.us>
Signed-off-by: NCong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Hold netns refcnt before call_rcu() and release it after
the tcf_exts_destroy() is done.

Note, on ->destroy() path we have to respect the return value
of tcf_exts_get_net(), on other paths it should always return
true, so we don't need to care.

Cc: Lucas Bates <lucasb@mojatatu.com>
Cc: Jamal Hadi Salim <jhs@mojatatu.com>
Cc: Jiri Pirko <jiri@resnulli.us>
Signed-off-by: NCong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Hold netns refcnt before call_rcu() and release it after
the tcf_exts_destroy() is done.

Note, on ->destroy() path we have to respect the return value
of tcf_exts_get_net(), on other paths it should always return
true, so we don't need to care.

Cc: Lucas Bates <lucasb@mojatatu.com>
Cc: Jamal Hadi Salim <jhs@mojatatu.com>
Cc: Jiri Pirko <jiri@resnulli.us>
Signed-off-by: NCong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Hold netns refcnt before call_rcu() and release it after
the tcf_exts_destroy() is done.

Cc: Lucas Bates <lucasb@mojatatu.com>
Cc: Jamal Hadi Salim <jhs@mojatatu.com>
Cc: Jiri Pirko <jiri@resnulli.us>
Signed-off-by: NCong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Hold netns refcnt before call_rcu() and release it after
the tcf_exts_destroy() is done.

Note, on ->destroy() path we have to respect the return value
of tcf_exts_get_net(), on other paths it should always return
true, so we don't need to care.

Cc: Lucas Bates <lucasb@mojatatu.com>
Cc: Jamal Hadi Salim <jhs@mojatatu.com>
Cc: Jiri Pirko <jiri@resnulli.us>
Signed-off-by: NCong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Hold netns refcnt before call_rcu() and release it after
the tcf_exts_destroy() is done.

Note, on ->destroy() path we have to respect the return value
of tcf_exts_get_net(), on other paths it should always return
true, so we don't need to care.

Cc: Lucas Bates <lucasb@mojatatu.com>
Cc: Jamal Hadi Salim <jhs@mojatatu.com>
Cc: Jiri Pirko <jiri@resnulli.us>
Signed-off-by: NCong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Hold netns refcnt before call_rcu() and release it after
the tcf_exts_destroy() is done.

Note, on ->destroy() path we have to respect the return value
of tcf_exts_get_net(), on other paths it should always return
true, so we don't need to care.

Cc: Lucas Bates <lucasb@mojatatu.com>
Cc: Jamal Hadi Salim <jhs@mojatatu.com>
Cc: Jiri Pirko <jiri@resnulli.us>
Signed-off-by: NCong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Hold netns refcnt before call_rcu() and release it after
the tcf_exts_destroy() is done.

Note, on ->destroy() path we have to respect the return value
of tcf_exts_get_net(), on other paths it should always return
true, so we don't need to care.

Cc: Lucas Bates <lucasb@mojatatu.com>
Cc: Jamal Hadi Salim <jhs@mojatatu.com>
Cc: Jiri Pirko <jiri@resnulli.us>
Signed-off-by: NCong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Hold netns refcnt before call_rcu() and release it after
the tcf_exts_destroy() is done.

Note, on ->destroy() path we have to respect the return value
of tcf_exts_get_net(), on other paths it should always return
true, so we don't need to care.

Cc: Lucas Bates <lucasb@mojatatu.com>
Cc: Jamal Hadi Salim <jhs@mojatatu.com>
Cc: Jiri Pirko <jiri@resnulli.us>
Signed-off-by: NCong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Hold netns refcnt before call_rcu() and release it after
the tcf_exts_destroy() is done.

Note, on ->destroy() path we have to respect the return value
of tcf_exts_get_net(), on other paths it should always return
true, so we don't need to care.

Cc: Lucas Bates <lucasb@mojatatu.com>
Cc: Jamal Hadi Salim <jhs@mojatatu.com>
Cc: Jiri Pirko <jiri@resnulli.us>
Signed-off-by: NCong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Instead of holding netns refcnt in tc actions, we can minimize
the holding time by saving it in struct tcf_exts instead. This
means we can just hold netns refcnt right before call_rcu() and
release it after tcf_exts_destroy() is done.

However, because on netns cleanup path we call tcf_proto_destroy()
too, obviously we can not hold netns for a zero refcnt, in this
case we have to do cleanup synchronously. It is fine for RCU too,
the caller cleanup_net() already waits for a grace period.

For other cases, refcnt is non-zero and we can safely grab it as
normal and release it after we are done.

This patch provides two new API for each filter to use:
tcf_exts_get_net() and tcf_exts_put_net(). And all filters now can
use the following pattern:

void __destroy_filter() {
  tcf_exts_destroy();
  tcf_exts_put_net();  // <== release netns refcnt
  kfree();
}
void some_work() {
  rtnl_lock();
  __destroy_filter();
  rtnl_unlock();
}
void some_rcu_callback() {
  tcf_queue_work(some_work);
}

if (tcf_exts_get_net())  // <== hold netns refcnt
  call_rcu(some_rcu_callback);
else
  __destroy_filter();

Cc: Lucas Bates <lucasb@mojatatu.com>
Cc: Jamal Hadi Salim <jhs@mojatatu.com>
Cc: Jiri Pirko <jiri@resnulli.us>
Signed-off-by: NCong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>