Previously, when using ethtool to change the RSS hash key, ethtool would
report back saying the old key was still being used and no error was
reported.  It was unclear whether it was being reported incorrectly or
being set incorrectly.  Debugging revealed 'i40e_set_rxfh()' returned
zero immediately instead of setting the key because a user defined
indirection table is not supplied when changing the hash key.

This fix instead changes it such that if an indirection table is not
supplied, then a default one is created and the hash key is now
correctly set.

Change-ID: Iddb621897ecf208650272b7ee46702cad7b69a71
Signed-off-by: Alan Brady <alan.brady@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

Joel Stanley says:

====================
ftgmac100 support for ast2500

This series adds support to the ftgmac100 driver for the Aspeed ast2400 and
ast2500 SoCs. In particular, they ensure the driver works correctly on the
ast2500 where the MAC block has seen some changes in register layout.

They have been tested on ast2400 and ast2500 systems with the NCSI stack and
with a directly attached PHY.

V2 reworks the two patches relating to PHYSTS_CHG into the one patch that
disables the interrupt instead of playing with interrupt sensitivity. I kept
patch 4 'net/faraday: Clear stale interrupts' which was first introduced to
clear the stale PHYSTS_CHG interrupt, as it helps keep us safe from unhygienic
(vendor) bootloaders.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

The PHYSTS_CHG (the ftgmac100's PHY IRQ) is telling the system to go
look at the PHY registers for a link status change.

The interrupt was causing issues on Aspeed SoC where some board designs
had an active high configuration, some active low, and in some cases
repurposed for other functions. When misconfigured Linux would chew 100%
of CPU cycles servicing interrupts:

 [   20.280000] ftgmac100 1e660000.ethernet eth0: [ISR] = 0x200: PHYSTS_CHG
 [   20.280000] ftgmac100 1e660000.ethernet eth0: [ISR] = 0x200: PHYSTS_CHG
 [   20.280000] ftgmac100 1e660000.ethernet eth0: [ISR] = 0x200: PHYSTS_CHG
 [   20.300000] ftgmac100 1e660000.ethernet eth0: [ISR] = 0x200: PHYSTS_CHG

While in the ftgmac100 IP can be configured for high, low and edge
sensitivity the current driver always polls the PHY, so we chose to mask
out the interrupt.

See https://patchwork.ozlabs.org/patch/672099/ for more discussion.
Signed-off-by: Joel Stanley <joel@jms.id.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

The Aspeed SoCs have a new MDIO interface as an option in the G4 and G5
SoCs. The old one is still available, so select it in order to remain
compatible with the ftgmac100 driver.
Signed-off-by: Joel Stanley <joel@jms.id.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

There is stale interrupt (PHYSTS_CHG in ISR, bit#6 in 0x0) from
the bootloader (uboot) when enabling the MAC. The stale interrupts
aren't part of kernel and should be cleared.

This clears the stale interrupts in ISR (0x0) when enabling the MAC.
Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
Signed-off-by: Joel Stanley <joel@jms.id.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

The RXDES and TXDES registers bits in the ftgmac100 indicates EDO{R,T}R
at bit position 15 for the Faraday Tech IP. However, the version of this
IP present in the Aspeed SoCs has these bits at position 30 in the
registers.

It appers that ast2400 SoCs support both positions, with the 15th bit
marked as reserved but still functional. In the ast2500 this bit is
reused for another function, so we need a work around.

This was confirmed with engineers from Aspeed that using bit 30 is
correct for both the ast2400 and ast2500 SoCs.
Signed-off-by: Joel Stanley <joel@jms.id.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

These bits are #defined at a fixed location. In order to support future
hardware that has chosen to move these bits around move the bits into a
member of the struct ftgmac100.
Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
Signed-off-by: Joel Stanley <joel@jms.id.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

The ftgmac100 hardware revision in e.g. the Aspeed AST2500 no longer
reserves all bits in RXDES#2 but instead uses the bottom 16 bits to
store MAC frame metadata. Avoid corruption by shifting struct page
pointers out to their own member in struct ftgmac100.
Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
Signed-off-by: Joel Stanley <joel@jms.id.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

Remove an open coded simple_open() function and replace file
operations references to the function with simple_open()
instead.

Generated by: scripts/coccinelle/api/simple_open.cocci
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

mdio_module_driver() makes the code simpler by eliminating
boilerplate code.
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Fixes the following sparse warning:

drivers/net/dsa/qca8k.c:259:22: warning:
 symbol 'qca8k_regmap_config' was not declared. Should it be static?
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Marcelo Ricardo Leitner says:

====================
Rename WORD_TRUNC/ROUND macros and use them

This patchset aims to rename these macros to a non-confusing name, as
reported by David Laight and David Miller, and to update all remaining
places to make use of it, which was 1 last remaining spot.

v3:
- Name it SCTP_PAD4 instead of SCTP_ALIGN4, as suggested by David Laight
v2:
- fixed 2nd patch summary

Details on the specific changelogs.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

And avoid the usage of '&~3'. This is the last place still not using
the macro.
Also break the line to make it easier to read.
Signed-off-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

To something more meaningful these days, specially because this is
working on packet headers or lengths and which are not tied to any CPU
arch but to the protocol itself.

So, WORD_TRUNC becomes SCTP_TRUNC4 and WORD_ROUND becomes SCTP_PAD4.
Reported-by: David Laight <David.Laight@ACULAB.COM>
Reported-by: David Miller <davem@davemloft.net>
Signed-off-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Tariq Toukan says:

====================
mlx5e XDP support

This series adds XDP support in mlx5e driver.
This includes the use cases: XDP_DROP, XDP_PASS, and XDP_TX.

Single stream performance tests show 16.5 Mpps for XDP_DROP,
and 12.4 Mpps for XDP_TX, with nice scalability for multiple streams/rings.

This rate of XDP_DROP is lower than the 32 Mpps we got in previous
implementation, when Striding RQ was used.

We moved to non-Striding RQ, as some XDP_TX requirements (like headroom,
packet-per-page) cannot be satisfied with the current Striding RQ HW,
and we decided to fully support both DROP/TX.

Few directions are considered in order to enable the faster rate for XDP_DROP,
e.g a possibility for users to enable Striding RQ so they choose optimized
XDP_DROP on the price of partial XDP_TX functionality, or some HW changes.

Series generated against net-next commit:
cf714ac1 'ipvlan: Fix dependency issue'

Thanks,
Tariq

V2:
* patch 8:
 - when XDP_TX fails, call mlx5e_page_release and drop the packet.
 - update xdp_tx counter within mlx5e_xmit_xdp_frame.
   (mlx5e_xmit_xdp_frame return value becomes obsolete, change it to void)
 - drop the packet for unknown XDP return code.
* patch 9:
 - use a boolean for xdp_doorbell in SQ struct, instead of dragging it
   throughout the functions calls.
 - handle doorbell and counters within mlx5e_xmit_xdp_frame.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

Previously we rang XDP SQ doorbell on every forwarded XDP packet.

Here we introduce a xmit more like mechanism that will queue up more
than one packet into SQ (up to RX napi budget) w/o notifying the hardware.

Once RX napi budget is consumed and we exit napi RX loop, we will
flush (doorbell) all XDP looped packets in case there are such.

XDP forward packet rate:

Comparing XDP with and w/o xmit more (bulk transmit):

RX Cores    XDP TX       XDP TX (xmit more)
---------------------------------------------------
1           6.5Mpps      12.4Mpps
2          13.2Mpps      24.2Mpps
4          25.2Mpps      36.3Mpps*
8          36.3Mpps*     36.3Mpps*

*My xmitter was limited to 36.3Mpps, so it is the bottleneck.
It seems that receive side can handle more.
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
Signed-off-by: Tariq Toukan <tariqt@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Adding support for XDP_TX forwarding from xdp program.
Using XDP, now user can loop packets out of the same port.

We create a dedicated TX SQ for each channel that will serve
XDP programs that return XDP_TX action to loop packets back to
the wire directly from the channel RQ RX path.

For that RX pages will now need to be mapped bi-directionally,
and on XDP_TX action we will sync the page back to device then
queue it into SQ for transmission.  The XDP xmit frame function will
report back to the RX path if the page was consumed (transmitted), if so,
RX path will forget about that page as if it were released to the stack.
Later on, on XDP TX completion, the page will be released back to the
page cache.

For simplicity this patch will hit a doorbell on every XDP TX packet.

Next patch will introduce a xmit more like mechanism that will
queue up more than one packet into SQ w/o notifying the hardware,
once RX napi loop is done we will hit doorbell once for all XDP TX
packets form the previous loop.  This should drastically improve
XDP TX performance.
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
Signed-off-by: Tariq Toukan <tariqt@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Make a clear separate between Regular SQ (TXQ) and ICO SQ creation,
destruction and union their mutual information structures.

Don't allocate redundant TXQ skb/wqe_info/dma_fifo arrays for ICO SQ.
And have a different SQ edge for ICO SQ than TXQ SQ, to be more
accurate.

In preparation for XDP TX support.
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
Signed-off-by: Tariq Toukan <tariqt@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Add support for the BPF_PROG_TYPE_PHYS_DEV hook in mlx5e driver.

When XDP is on we make sure to change channels RQs type to
MLX5_WQ_TYPE_LINKED_LIST rather than "striding RQ" type to
ensure "page per packet".

On XDP set, we fail if HW LRO is set and request from user to turn it
off.  Since on ConnectX4-LX HW LRO is always on by default, this will be
annoying, but we prefer not to enforce LRO off from XDP set function.

Full channels reset (close/open) is required only when setting XDP
on/off.

When XDP set is called just to exchange programs, we will update
each RQ xdp program on the fly and for synchronization with current
data path RX activity of that RQ, we temporally disable that RQ and
ensure RX path is not running, quickly update and re-enable that RQ,
for that we do:
	- rq.state = disabled
	- napi_synnchronize
	- xchg(rq->xdp_prg)
	- rq.state = enabled
	- napi_schedule // Just in case we've missed an IRQ

Packet rate performance testing was done with pktgen 64B packets and on
TX side and, TC drop action on RX side compared to XDP fast drop.

CPU: Intel(R) Xeon(R) CPU E5-2680 v3 @ 2.50GHz

Comparison is done between:
	1. Baseline, Before this patch with TC drop action
	2. This patch with TC drop action
	3. This patch with XDP RX fast drop

RX Cores  Baseline(TC drop)    TC drop    XDP fast Drop
--------------------------------------------------------------
1            5.3Mpps           5.3Mpps     16.5Mpps
2           10.2Mpps          10.2Mpps     31.3Mpps
4           20.5Mpps          19.9Mpps     36.3Mpps*

*My xmitter was limited to 36.3Mpps, so it is the bottleneck.
It seems that receive side can handle more.
Signed-off-by: Rana Shahout <ranas@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
Signed-off-by: Tariq Toukan <tariqt@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Add two helper functions to allow dynamic changes of RQ type.

mlx5e_set_rq_priv_params and mlx5e_set_rq_type_params will be
used on netdev creation to determine the default RQ type.

This will be needed later for downstream patches of XDP support.
When enabling XDP we will dynamically move from striding RQ to
linked list RQ type.
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
Signed-off-by: Tariq Toukan <tariqt@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Before this patch LRO size was 64K, now with build_skb requires
extra room, headroom + sizeof(skb_shared_info) added to the data
buffer will make  wqe size or page_frag_size slightly larger than
64K which will demand order 5 page instead of order 4 in 4K page systems.

We take those extra bytes from hardware LRO data size in order to not
increase the required page order for when hardware LRO is enabled.
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
Signed-off-by: Tariq Toukan <tariqt@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

We have two types of RX RQs, and they use two separate sets of
info arrays and structures in RX data path function.  Today those
structures are mutually exclusive per RQ type, hence one kind is
allocated on RQ creation according to the RQ type.

For better cache locality and to minimalize the
sizeof(struct mlx5e_rq), in this patch we define them as a union.
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
Signed-off-by: Tariq Toukan <tariqt@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

For non-striding RQ configuration before this patch we had a ring
with pre-allocated SKBs and mapped the SKB->data buffers for
device.

For robustness and better RX data buffers management, we allocate a
page per packet and build_skb around it.

This patch (which is a prerequisite for XDP) will actually reduce
performance for normal stack usage, because we are now hitting a bottleneck
in the page allocator. We use the page-cache to restore or even improve
performance in comparison to the old RX scheme.

Packet rate performance testing was done with pktgen 64B packets on xmit
side and TC ingress dropping action on RX side.

CPU: Intel(R) Xeon(R) CPU E5-2680 v3 @ 2.50GHz

Comparison is done between:
 1.Baseline, before 'net/mlx5e: Build RX SKB on demand'
 2.Build SKB with RX page cache (This patch)

RX Cores  Baseline    Build SKB+page-cache    Improvement
-----------------------------------------------------------
1          4.16Mpps       5.33Mpps                28%
2          7.16Mpps      10.24Mpps                43%
4         13.61Mpps      20.51Mpps                51%
8         25.32Mpps      32.00Mpps                26%

All respective cores were 100% utilized.
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
Signed-off-by: Tariq Toukan <tariqt@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

We saw sch_fq drops caused by the per flow limit of 100 packets and TCP
when dealing with large cwnd and bursts of retransmits.

Even after increasing the limit to 1000, and even after commit
10d3be56 ("tcp-tso: do not split TSO packets at retransmit time"),
we can still have these drops.

Under certain conditions, TCP can spend a considerable amount of
time queuing thousands of skbs in a single tcp_xmit_retransmit_queue()
invocation, incurring latency spikes and stalls of other softirq
handlers.

This patch implements TSQ for retransmits, limiting number of packets
and giving more chance for scheduling packets in both ways.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Andrew Lunn says:

====================
Preparation for mv88e6390

These two patches are a couple of preparation steps for supporting the
the MV88E6390 family of chips. This is a new generation from Marvell,
and will need more feature flags than are currently available in an
unsigned long. Expand to an unsigned long long. The MV88E6390 also
places its port registers somewhere else, so add a wrapper around port
register access.

v2:
 Rework wrappers to use mv88e6xxx_{read|write}
 Simpliy some (err < ) to (err)
Add Reviewed by tag.

v3::
 reg = reg & foo -> reg &= foo
 Fix over zealous s/ret/err
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

We are soon going to run out of flag bits on 32bit systems. Convert to
unsigned long long.
Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

There is a device coming soon which places its port registers
somewhere different to all other Marvell switches supported so far.
Add helper functions for reading/writing port registers, making it
easier to handle this new device.
Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Drivers must be ready to accept NULL from ptp_clock_register() if the
PTP clock subsystem is configured out.

This patch documents that and ensures that all drivers cope well
with a NULL return.
Signed-off-by: Nicolas Pitre <nico@linaro.org>
Reviewed-by: Eugenia Emantayev <eugenia@mellanox.com>
Acked-by: Richard Cochran <richardcochran@gmail.com>
Acked-by: Edward Cree <ecree@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

The ethtool api {get|set}_settings is deprecated.
We move this driver to new api {get|set}_link_ksettings.
Signed-off-by: Philippe Reynes <tremyfr@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

The private structure contain a pointer to phydev, but the structure
net_device already contain such pointer. So we can remove the pointer
phydev in the private structure, and update the driver to use the
one contained in struct net_device.
Signed-off-by: Philippe Reynes <tremyfr@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

add the missing commits about
1)
Commit d3bd1ce4
("remove redundant free_irq for devm_request_ir allocated irq")
2)
Commit 7c6b0d76
("fix logic unbalance between probe and remove")

during merge for conflicts overlapping commits by
Commit b20b378d
("Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net")
Signed-off-by: Sean Wang <sean.wang@mediatek.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Rahul Lakkireddy says:

====================
cxgb4: add support for offloading TC u32 filters

This series of patches add support to offload TC u32 filters onto
Chelsio NICs.

Patch 1 moves current common filter code to separate files
in order to provide a common api for performing packet classification
and filtering in Chelsio NICs.

Patch 2 enables filters for normal NIC configuration and implements
common api for setting and deleting filters.

Patches 3-5 add support for TC u32 offload via ndo_setup_tc.

---
v3:

Based on review and suggestion from David Miller <davem@davemloft.net>
- Fixed all local variable declarations by placing them in longest line
  first and shortest line last order.

v2:

Based on review and suggestions from Jiri Pirko <jiri@resnulli.us>:
- Replaced macros S and U with appropriate static helper functions.
- Moved completion code for set and delete filters to respective
  functions cxgb4_set_filter() and cxgb4_del_filter().  Renamed the
  original functions to __cxgb4_set_filter() and __cxgb4_del_filter()
  in case synchronization is not required.
- Dropped debugfs patch.
- Merged code for inserting and deleting u32 filters into a single
  patch.
- Reworked and fixed bugs with traversing the actions list.
- Removed all unnecessary extra ().
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

Add support for dropping matched packets in hardware.  Also add support
for re-directing matched packets to a specified port in hardware.
Signed-off-by: Rahul Lakkireddy <rahul.lakkireddy@chelsio.com>
Signed-off-by: Hariprasad Shenai <hariprasad@chelsio.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Add support for offloading u32 filter onto hardware.  Links are stored
in a jump table to perform necessary jumps to match TCP/UDP header.
When inserting rules in the linked bucket, the TCP/UDP match fields
in the corresponding entry of the jump table are appended to the filter
rule before insertion.  If a link is deleted, then all corresponding
filters associated with the link are also deleted.  Also enable
hardware tc offload as a supported feature.
Signed-off-by: Rahul Lakkireddy <rahul.lakkireddy@chelsio.com>
Signed-off-by: Hariprasad Shenai <hariprasad@chelsio.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Parse information sent by u32 into internal filter specification.
Add support for parsing several fields in IPv4, IPv6, TCP, and UDP.
Signed-off-by: Rahul Lakkireddy <rahul.lakkireddy@chelsio.com>
Signed-off-by: Hariprasad Shenai <hariprasad@chelsio.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Enable filters for non-offload configuration and add common api support
for setting and deleting filters in LE-TCAM region of the hardware.

IPv4 filters occupy one slot.  IPv6 filters occupy 4 slots and must
be on a 4-slot boundary.  IPv4 filters can not occupy a slot belonging
to IPv6 and the vice-versa is also true.

Filters are set and deleted asynchronously.  Use completion to wait
for reply from firmware in order to allow for synchronization if needed.
Signed-off-by: Rahul Lakkireddy <rahul.lakkireddy@chelsio.com>
Signed-off-by: Hariprasad Shenai <hariprasad@chelsio.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Move common filter code to separate files.  Also fix the following
checkpatch checks.

CHECK: Comparison to NULL could be written "!f->l2t"
+               if (f->l2t == NULL) {

CHECK: spaces preferred around that '/' (ctx:VxV)
+       fwr->len16_pkd = htonl(FW_WR_LEN16_V(sizeof(*fwr)/16));
Signed-off-by: Rahul Lakkireddy <rahul.lakkireddy@chelsio.com>
Signed-off-by: Hariprasad Shenai <hariprasad@chelsio.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Fix 'skb_vlan_pop' to use eth_type_vlan instead of directly comparing
skb->protocol to ETH_P_8021Q or ETH_P_8021AD.
Signed-off-by: Shmulik Ladkani <shmulik.ladkani@gmail.com>
Reviewed-by: Pravin B Shelar <pshelar@ovn.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

In 93515d53
  "net: move vlan pop/push functions into common code"
skb_vlan_pop was moved from its private location in openvswitch to
skbuff common code.

In case skb has non hw-accel vlan tag, the original 'pop_vlan()' assured
that skb->len is sufficient (if skb->len < VLAN_ETH_HLEN then pop was
considered a no-op).

This validation was moved as is into the new common 'skb_vlan_pop'.

Alas, in its original location (openvswitch), there was a guarantee that
'data' points to the mac_header, therefore the 'skb->len < VLAN_ETH_HLEN'
condition made sense.
However there's no such guarantee in the generic 'skb_vlan_pop'.

For short packets received in rx path going through 'skb_vlan_pop',
this causes 'skb_vlan_pop' to fail pop-ing a valid vlan hdr (in the non
hw-accel case) or to fail moving next tag into hw-accel tag.

Remove the 'skb->len < VLAN_ETH_HLEN' condition entirely:
It is superfluous since inner '__skb_vlan_pop' already verifies there
are VLAN_ETH_HLEN writable bytes at the mac_header.

Note this presents a slight change to skb_vlan_pop() users:
In case total length is smaller than VLAN_ETH_HLEN, skb_vlan_pop() now
returns an error, as opposed to previous "no-op" behavior.
Existing callers (e.g. tc act vlan, ovs) usually drop the packet if
'skb_vlan_pop' fails.

Fixes: 93515d53 ("net: move vlan pop/push functions into common code")
Signed-off-by: Shmulik Ladkani <shmulik.ladkani@gmail.com>
Cc: Pravin Shelar <pshelar@ovn.org>
Reviewed-by: Pravin B Shelar <pshelar@ovn.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

Shmulik Ladkani says:

====================
act_vlan: Introduce TCA_VLAN_ACT_MODIFY vlan action

TCA_VLAN_ACT_MODIFY allows one to change an existing tag.

It accepts same attributes as TCA_VLAN_ACT_PUSH (protocol, id,
priority).
If packet is vlan tagged, then the tag gets overwritten according to
user specified attributes.

For example, this allows user to replace a tag's vid while preserving
its priority bits (as opposed to "action vlan pop pipe action vlan push").
====================
Signed-off-by: David S. Miller <davem@davemloft.net>