In this situation (VLAN filtering disabled on br0):

    br0.10
     /
   br0
   / \
swp0 swp1

When a frame is transmitted from the VLAN upper, the bridge will send
it down to one of the switch ports with forward offloading
enabled. This will cause tag_dsa to generate a FORWARD tag. Before
this change, that tag would have it's VID set to 10, even though VID
10 is not loaded in the VTU.

Before the blamed commit, the frame would trigger a VTU miss and be
forwarded according to the PVT configuration. Now that all fabric
ports are in 802.1Q secure mode, the frame is dropped instead.

Therefore, restrict the condition under which we rewrite an 802.1Q tag
to a DSA tag. On standalone port's, reuse is always safe since we will
always generate FROM_CPU tags in that case. For bridged ports though,
we must ensure that VLAN filtering is enabled, which in turn
guarantees that the VID in question is loaded into the VTU.

Fixes: d352b20f ("net: dsa: mv88e6xxx: Improve multichip isolation of standalone ports")
Signed-off-by: Tobias Waldekranz <tobias@waldekranz.com>
Tested-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Vladimir Oltean <olteanv@gmail.com>
Link: https://lore.kernel.org/r/20220307110548.812455-1-tobias@waldekranz.comSigned-off-by: Paolo Abeni <pabeni@redhat.com>

In case the MAC is using 'netif_rx()' to deliver the skb up the network
stack, it needs to check whether 'skb_defer_rx_timestmap()' is necessary
or not. In case is needed then don't call 'netif_rx()'
Signed-off-by: Horatiu Vultur <horatiu.vultur@microchip.com>
Link: https://lore.kernel.org/r/20220307094632.3764266-1-horatiu.vultur@microchip.comSigned-off-by: Paolo Abeni <pabeni@redhat.com>

In case of DT-configured systems it may be hard to identify the PHY
interrupt in the /proc/interrupts output. Therefore add the name to
the id to make clearer that it's about a device on a muxed mdio bus.
In my case:

Now: mdio_mux-0.e40908ff:08
Before: 0.e40908ff:08
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Link: https://lore.kernel.org/r/00b4bb1e-98f9-b4e7-5549-e095a4701f66@gmail.comSigned-off-by: Paolo Abeni <pabeni@redhat.com>

During the process of driver probing, probe function should return < 0
for failure, otherwise kernel will treat value >= 0 as success.

Therefore, the driver should set 'err' to -ENODEV when
'adapter->registered_device_map' is NULL. Otherwise kernel will assume
that the driver has been successfully probed and will cause unexpected
errors.
Signed-off-by: Zheyu Ma <zheyuma97@gmail.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Link: https://lore.kernel.org/r/1646546192-32737-1-git-send-email-zheyuma97@gmail.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

Pragma unroll was introduced around GCC 8, whereas current xsk code in
ice that prepares loop_unrolled_for macro that is based on mentioned
pragma, compares GCC version against 4, which is wrong and Stephen
found this out by compiling kernel with GCC 5.4 [0].

Fix this mistake and check if GCC version is >= 8.

[0]: https://lore.kernel.org/netdev/20220307213659.47658125@canb.auug.org.au/

Fixes: 126cdfe1 ("ice: xsk: Improve AF_XDP ZC Tx and use batching API")
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Link: https://lore.kernel.org/r/20220307231353.56638-1-maciej.fijalkowski@intel.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

The previous check handled the "if (!nh)" condition so we know "nh"
is non-NULL here.  Delete the check and pull the code in one tab.
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Nikolay Aleksandrov <razor@blackwall.org>
Reviewed-by: Roopa Prabhu <roopa@nvidia.com>
Link: https://lore.kernel.org/r/20220307125735.GC16710@kiliSigned-off-by: Jakub Kicinski <kuba@kernel.org>

The > ARRAY_SIZE() needs to be >= ARRAY_SIZE() to prevent an out of
bounds access.

Fixes: 9f492c4c ("ptp: ocp: add TOD debug information")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Richard Cochran <richardcochran@gmail.com>
Acked-by: Jonathan Lemon <jonathan.lemon@gmail.com>
Link: https://lore.kernel.org/r/20220307141318.GA18867@kiliSigned-off-by: Jakub Kicinski <kuba@kernel.org>

The clang static analyzer reports this issue
rtnetlink.c:5481:2: warning: Undefined or garbage
  value returned to caller
  return err;
  ^~~~~~~~~~

There is a function level err variable, in the
list_for_each_entry_rcu block there is a shadow
err.  Remove the shadow.

In the same block, the call to nla_nest_start_noflag()
can fail without setting an err.  Set the err
to -EMSGSIZE.

Fixes: 216e6906 ("net: rtnetlink: rtnl_fill_statsinfo(): Permit non-EMSGSIZE error returns")
Signed-off-by: Tom Rix <trix@redhat.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Reviewed-by: Petr Machata <petrm@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Clang static analysis reports this representative issue
dsa.c:486:2: warning: Undefined or garbage value
  returned to caller
  return err;
  ^~~~~~~~~~

err is only set in the loop.  If the loop is empty,
garbage will be returned.  So initialize err to 0
to handle this noop case.
Signed-off-by: Tom Rix <trix@redhat.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Vladimir Oltean <olteanv@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Fit the following coccicheck warning:
tools/testing/selftests/net/reuseport_bpf_numa.c:89:28-29:
WARNING: Use ARRAY_SIZE.

It has been tested with gcc (Debian 8.3.0-6) 8.3.0 on x86_64.
Signed-off-by: Guo Zhengkui <guozhengkui@vivo.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Fix the following coccicheck warning:
drivers/net/ethernet/netronome/nfp/nfp_net_common.c:3434:8-48: WARNING
avoid newline at end of message in NL_SET_ERR_MSG_MOD
Signed-off-by: Guo Zhengkui <guozhengkui@vivo.com>
Reviewed-by: Niklas Söderlund <niklas.soderlund@corigine.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

kernel test robot reports multiple warning for smc_sysctl:

  In file included from net/smc/smc_sysctl.c:17:
>> net/smc/smc_sysctl.h:23:5: warning: no previous prototype \
	for function 'smc_sysctl_init' [-Wmissing-prototypes]
  int smc_sysctl_init(void)
       ^
and
  >> WARNING: modpost: vmlinux.o(.text+0x12ced2d): Section mismatch \
  in reference from the function smc_sysctl_exit() to the variable
  .init.data:smc_sysctl_ops
  The function smc_sysctl_exit() references
  the variable __initdata smc_sysctl_ops.
  This is often because smc_sysctl_exit lacks a __initdata
  annotation or the annotation of smc_sysctl_ops is wrong.

and
  net/smc/smc_sysctl.c: In function 'smc_sysctl_init_net':
  net/smc/smc_sysctl.c:47:17: error: 'struct netns_smc' has no member named 'smc_hdr'
     47 |         net->smc.smc_hdr = register_net_sysctl(net, "net/smc", table);

Since we don't need global sysctl initialization. To make things
clean and simple, remove the global pernet_operations and
smc_sysctl_{init|exit}. Call smc_sysctl_net_{init|exit} directly
from smc_net_{init|exit}.

Also initialized sysctl_autocorking_size if CONFIG_SYSCTL it not
set, this make sure SMC autocorking is enabled by default if
CONFIG_SYSCTL is not set.

Fixes: 462791bb ("net/smc: add sysctl interface for SMC")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Dust Li <dust.li@linux.alibaba.com>
Tested-by: Randy Dunlap <rdunlap@infradead.org> # build-tested
Signed-off-by: David S. Miller <davem@davemloft.net>

Sebastian Andrzej Siewior says:

====================
net: Convert user to netif_rx(), part 3.

This is the third and last batch of converting netif_rx_ni() caller to
netif_rx(). The change making this possible is net-next and
netif_rx_ni() is a wrapper around netif_rx(). This is a clean up in
order to remove netif_rx_ni().

The micrel phy driver is patched twice within this series: the first is
is to replace netif_rx_ni() and second to move netif_rx() outside of the
IRQ-off section. It is probably simpler to keep it within this series.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

lan8814_match_rx_ts() invokes netif_rx() with disables interrupts
outside which will create a warning. Invoking netif_rx_ni() with
disabled interrupts is wrong even without the recent rework because
netif_rx_ni() would enable interrupts while processing the softirq. This
in turn can lead to dead lock if an interrupts triggers and attempts to
acquire kszphy_ptp_priv::rx_ts_lock.

Move netif_rx() outside the IRQ-off section.

Cc: Andrew Lunn <andrew@lunn.ch>
Cc: Heiner Kallweit <hkallweit1@gmail.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Divya Koppera <Divya.Koppera@microchip.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

Remove netif_rx_any_context and netif_rx_ni() because there are no more
users in tree.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

Since commit
   baebdf48 ("net: dev: Makes sure netif_rx() can be invoked in any context.")

the function netif_rx() can be used in preemptible/thread context as
well as in interrupt context.

Use netif_rx().

Cc: Andrew Lunn <andrew@lunn.ch>
Cc: Heiner Kallweit <hkallweit1@gmail.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Divya Koppera <Divya.Koppera@microchip.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

Since commit
   baebdf48 ("net: dev: Makes sure netif_rx() can be invoked in any context.")

the function netif_rx() can be used in preemptible/thread context as
well as in interrupt context.

Use netif_rx().

Cc: Remi Denis-Courmont <courmisch@gmail.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

Since commit
   baebdf48 ("net: dev: Makes sure netif_rx() can be invoked in any context.")

the function netif_rx() can be used in preemptible/thread context as
well as in interrupt context.

Use netif_rx().

Cc: Marcel Holtmann <marcel@holtmann.org>
Cc: Johan Hedberg <johan.hedberg@gmail.com>
Cc: Luiz Augusto von Dentz <luiz.dentz@gmail.com>
Cc: linux-bluetooth@vger.kernel.org
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

Since commit
   baebdf48 ("net: dev: Makes sure netif_rx() can be invoked in any context.")

the function netif_rx() can be used in preemptible/thread context as
well as in interrupt context.

Use netif_rx().

Cc: Antonio Quartulli <a@unstable.cc>
Cc: Marek Lindner <mareklindner@neomailbox.ch>
Cc: Simon Wunderlich <sw@simonwunderlich.de>
Cc: Sven Eckelmann <sven@narfation.org>
Cc: b.a.t.m.a.n@lists.open-mesh.org
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Acked-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

Since commit
   baebdf48 ("net: dev: Makes sure netif_rx() can be invoked in any context.")

the function netif_rx() can be used in preemptible/thread context as
well as in interrupt context.

Use netif_rx().

Cc: Jon Maloy <jmaloy@redhat.com>
Cc: Ying Xue <ying.xue@windriver.com>
Cc: tipc-discussion@lists.sourceforge.net
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

Since commit
   baebdf48 ("net: dev: Makes sure netif_rx() can be invoked in any context.")

the function netif_rx() can be used in preemptible/thread context as
well as in interrupt context.

Use netif_rx().
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

Since commit
   baebdf48 ("net: dev: Makes sure netif_rx() can be invoked in any context.")

the function netif_rx() can be used in preemptible/thread context as
well as in interrupt context.

Use netif_rx().

Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: linux-staging@lists.linux.dev
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

Since commit
   baebdf48 ("net: dev: Makes sure netif_rx() can be invoked in any context.")

the function netif_rx() can be used in preemptible/thread context as
well as in interrupt context.

Use netif_rx().

Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Alexandra Winter <wintera@linux.ibm.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Wenjia Zhang <wenjia@linux.ibm.com>
Cc: linux-s390@vger.kernel.org
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

Kurt Kanzenbach says:

====================
ptp: Add generic is_sync() function

as multiple PHY drivers such as micrel or TI dp83640 need to inspect whether a
given skb represents a PTP Sync message, provide a generic function for it. This
avoids code duplication and can be reused by future PHY IEEE 1588 implementations.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

Use generic ptp_msg_is_sync() function to avoid code duplication.
Signed-off-by: Kurt Kanzenbach <kurt@linutronix.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

Use generic ptp_msg_is_sync() function to avoid code duplication.
Signed-off-by: Kurt Kanzenbach <kurt@linutronix.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

PHY drivers such as micrel or dp83640 need to analyze whether a given
skb is a PTP sync message for one step functionality.

In order to avoid code duplication introduce a generic function and
move it to ptp classify.
Signed-off-by: Kurt Kanzenbach <kurt@linutronix.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

Signed-off-by: Lianjie Zhang <zhanglianjie@uniontech.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Sebastian Andrzej Siewior says:

====================
net: Convert user to netif_rx(), part 2.

This is the second batch of converting netif_rx_ni() caller to
netif_rx(). The change making this possible is net-next and
netif_rx_ni() is a wrapper around netif_rx(). This is a clean up in
order to remove netif_rx_ni().

The brcmfmac changes are slilghtly larger because the inirq parameter
can be removed.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

Since commit
   baebdf48 ("net: dev: Makes sure netif_rx() can be invoked in any context.")

the function netif_rx() can be used in preemptible/thread context as
well as in interrupt context.

Use netif_rx().

Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: linux-wireless@vger.kernel.org
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

Since commit
   baebdf48 ("net: dev: Makes sure netif_rx() can be invoked in any context.")

the function netif_rx() can be used in preemptible/thread context as
well as in interrupt context.

Use netif_rx().

Cc: Amitkumar Karwar <amitkarwar@gmail.com>
Cc: Ganapathi Bhat <ganapathi017@gmail.com>
Cc: Kalle Valo <kvalo@kernel.org>
Cc: Sharvari Harisangam <sharvari.harisangam@nxp.com>
Cc: Xinming Hu <huxinming820@gmail.com>
Cc: libertas-dev@lists.infradead.org
Cc: linux-wireless@vger.kernel.org
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

Since commit
   baebdf48 ("net: dev: Makes sure netif_rx() can be invoked in any context.")

the function netif_rx() can be used in preemptible/thread context as
well as in interrupt context.

Use netif_rx().

Cc: Arend van Spriel <aspriel@gmail.com>
Cc: Chi-hsien Lin <chi-hsien.lin@infineon.com>
Cc: Chung-hsien Hsu <chung-hsien.hsu@infineon.com>
Cc: Franky Lin <franky.lin@broadcom.com>
Cc: Hante Meuleman <hante.meuleman@broadcom.com>
Cc: Kalle Valo <kvalo@kernel.org>
Cc: SHA-cyfmac-dev-list@infineon.com
Cc: Wright Feng <wright.feng@infineon.com>
Cc: brcm80211-dev-list.pdl@broadcom.com
Cc: linux-wireless@vger.kernel.org
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

Since commit
   baebdf48 ("net: dev: Makes sure netif_rx() can be invoked in any context.")

the function netif_rx() can be used in preemptible/thread context as
well as in interrupt context.

Use netif_rx().

Cc: Kalle Valo <kvalo@kernel.org>
Cc: Maya Erez <merez@codeaurora.org>
Cc: linux-wireless@vger.kernel.org
Cc: wil6210@qti.qualcomm.com
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

Since commit
   baebdf48 ("net: dev: Makes sure netif_rx() can be invoked in any context.")

the function netif_rx() can be used in preemptible/thread context as
well as in interrupt context.

Use netif_rx().
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Acked-by: Oliver Hartkopp <socketcan@hartkopp.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

Since commit
   baebdf48 ("net: dev: Makes sure netif_rx() can be invoked in any context.")

the function netif_rx() can be used in preemptible/thread context as
well as in interrupt context.

Use netif_rx().

Cc: Jeremy Kerr <jk@codeconstruct.com.au>
Cc: Matt Johnston <matt@codeconstruct.com.au>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

Since commit
   baebdf48 ("net: dev: Makes sure netif_rx() can be invoked in any context.")

the function netif_rx() can be used in preemptible/thread context as
well as in interrupt context.

Use netif_rx().

Cc: Marc Kleine-Budde <mkl@pengutronix.de>
Cc: Oliver Hartkopp <socketcan@hartkopp.net>
Cc: Wolfgang Grandegger <wg@grandegger.com>
Cc: linux-can@vger.kernel.org
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Acked-by: Oliver Hartkopp <socketcan@hartkopp.net>
Acked-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

Since commit
   baebdf48 ("net: dev: Makes sure netif_rx() can be invoked in any context.")

the function netif_rx() can be used in preemptible/thread context as
well as in interrupt context.

Use netif_rx().

Cc: Andrew Lunn <andrew@lunn.ch>
Cc: Heiner Kallweit <hkallweit1@gmail.com>
Cc: Radu Pirea <radu-nicolae.pirea@oss.nxp.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Russell King <linux@armlinux.org.uk>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

Dongli Zhang says:

====================
tun/tap: use kfree_skb_reason() to trace dropped skb

The commit c504e5c2 ("net: skb: introduce kfree_skb_reason()") has
introduced the kfree_skb_reason() to help track the reason.

The tun and tap are commonly used as virtio-net/vhost-net backend. This is to
use kfree_skb_reason() to trace the dropped skb for those two drivers.

Changed since v1:
- I have renamed many of the reasons since v1. I make them as generic as
  possible so that they can be re-used by core networking and drivers.

Changed since v2:
- declare drop_reason as type "enum skb_drop_reason"
- handle the drop in skb_list_walk_safe() case for tap driver, and
  kfree_skb_list_reason() is introduced

Changed since v3 (only for PATCH 4/4):
- rename to TAP_FILTER and TAP_TXFILTER
- honor reverse xmas tree style declaration for 'drop_reason' in
  tun_net_xmit()

Changed since v4:
- make kfree_skb_list() static inline
- add 'computation' to SKB_CSUM comment
- change COPY_DATA to UCOPY_FAULT
- add 'metadata' to DEV_HDR comment
- expand comment on DEV_READY
- change SKB_TRIM to NOMEM
- chnage SKB_PULL to HDR_TRUNC
Changed since v5:
- rebase to net-next

The following reasons are introduced.

- SKB_DROP_REASON_SKB_CSUM
- SKB_DROP_REASON_SKB_GSO_SEG
- SKB_DROP_REASON_SKB_UCOPY_FAULT
- SKB_DROP_REASON_DEV_HDR
- SKB_DROP_REASON_FULL_RING
- SKB_DROP_REASON_DEV_READY
- SKB_DROP_REASON_NOMEM
- SKB_DROP_REASON_HDR_TRUNC
- SKB_DROP_REASON_TAP_FILTER
- SKB_DROP_REASON_TAP_TXFILTER

This is the output for TUN device.

          <idle>-0       [029] ..s1.   450.727651: kfree_skb: skbaddr=0000000023d235cc protocol=0 location=00000000a6748854 reason: NOT_SPECIFIED
          <idle>-0       [000] b.s3.   451.165671: kfree_skb: skbaddr=000000006b5de7cc protocol=4 location=000000007c2b9eae reason: FULL_RING
          <idle>-0       [000] b.s3.   453.149650: kfree_skb: skbaddr=000000006b5de7cc protocol=4 location=000000007c2b9eae reason: FULL_RING
          <idle>-0       [000] b.s3.   455.133576: kfree_skb: skbaddr=000000006b5de7cc protocol=4 location=000000007c2b9eae reason: FULL_RING
          <idle>-0       [000] b.s3.   457.117566: kfree_skb: skbaddr=000000006b5de7cc protocol=4 location=000000007c2b9eae reason: FULL_RING

This is the output for TAP device.

          arping-7053    [006] ..s1.  1000.047753: kfree_skb: skbaddr=000000008618a587 protocol=2054 location=00000000743ad4a7 reason: FULL_RING
          <idle>-0       [022] ..s1.  1000.778514: kfree_skb: skbaddr=000000002c1e706c protocol=0 location=00000000a6748854 reason: NOT_SPECIFIED
          arping-7053    [006] ..s1.  1001.047830: kfree_skb: skbaddr=000000008618a587 protocol=2054 location=00000000743ad4a7 reason: FULL_RING
          arping-7053    [006] ..s1.  1002.047918: kfree_skb: skbaddr=000000008618a587 protocol=2054 location=00000000743ad4a7 reason: FULL_RING
          arping-7053    [006] ..s1.  1003.048017: kfree_skb: skbaddr=000000008618a587 protocol=2054 location=00000000743ad4a7 reason: FULL_RING
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

The TUN can be used as vhost-net backend. E.g, the tun_net_xmit() is the
interface to forward the skb from TUN to vhost-net/virtio-net.

However, there are many "goto drop" in the TUN driver. Therefore, the
kfree_skb_reason() is involved at each "goto drop" to help userspace
ftrace/ebpf to track the reason for the loss of packets.

The below reasons are introduced:

- SKB_DROP_REASON_DEV_READY
- SKB_DROP_REASON_NOMEM
- SKB_DROP_REASON_HDR_TRUNC
- SKB_DROP_REASON_TAP_FILTER
- SKB_DROP_REASON_TAP_TXFILTER

Cc: Joao Martins <joao.m.martins@oracle.com>
Cc: Joe Jin <joe.jin@oracle.com>
Signed-off-by: Dongli Zhang <dongli.zhang@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

No functional change.

Just to split the if statement into different conditions to use
kfree_skb_reason() to trace the reason later.

Cc: Joao Martins <joao.m.martins@oracle.com>
Cc: Joe Jin <joe.jin@oracle.com>
Signed-off-by: Dongli Zhang <dongli.zhang@oracle.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>