This patch moves the ksz_chip_data in ksz8795 and ksz9477 to ksz_common.
At present, the dev->chip_id is iterated with the ksz_chip_data and then
copy its value to the ksz_dev structure. These values are declared as
constant.
Instead of copying the values and referencing it, this patch update the
dev->info to the ksz_chip_data based on the chip_id in the init
function. And also update the ksz_chip_data values for the LAN937x based
switches.
Signed-off-by: Arun Ramadoss <arun.ramadoss@microchip.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Reviewed-by: Vladimir Oltean <olteanv@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

The port_cnt value in the structure is not used in the switch_init.
Instead it uses the fls(chip->cpu_port), this is due to one of port in
the ksz8794 unavailable. The cpu_port for the 8794 is 0x10, fls(0x10) =
5, hence updating it directly in the ksz_chip_data structure in order to
same with all the other switches in ksz8795.c and ksz9477.c files.
Signed-off-by: Arun Ramadoss <arun.ramadoss@microchip.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Reviewed-by: Vladimir Oltean <olteanv@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Saeed Mahameed says:

====================
mlx5-updates-2022-05-17

MISC updates to mlx5 dirver

1) Aya Levin allows relaxed ordering over VFs

2) Gal Pressman Adds support XDP SQs for uplink representors in switchdev mode

3) Add debugfs TC stats and command failure syndrome for debuggability

4) Tariq uses variants of vzalloc where it could help

5) Multiport eswitch support from Elic Cohen:

Eli Cohen Says:
===============

The multiport eswitch feature allows to forward traffic from a
representor net device to the uplink port of an associated eswitch's
uplink port.

This feature requires creating a LAG object. Since LAG can be created
only once for a function, the feature is mutual exclusive with either
bonding or multipath.

Multipath eswitch mode is entered automatically these conditions are
met:
1. No other LAG related mode is active.
2. A rule that explicitly forwards to an uplink port is inserted.

The implementation maintains a reference count on such rules. When the
reference count reaches zero, the LAG is released and other modes may be
used.

When an explicit rule that explicitly forwards to an uplink port is
inserted while another LAG mode is active, that rule will not be
offloaded by the hardware since the hardware cannot guarantee that the
rule will actually be forwarded to that port.

Example rules that forwards to an uplink port is:

$ tc filter add dev rep0 root flower action mirred egress \
  redirect dev uplinkrep0

$ tc filter add dev rep0 root flower action mirred egress \
  redirect dev uplinkrep1

This feature is supported only if LAG_RESOURCE_ALLOCATION firmware
configuration parameter is set to true.

The series consists of three patches:
1. Lag state machine refactor
   This patch does not add new functionality but rather changes the way
   the state of the LAG is maintained.
2. Small fix to remove unused argument.
3. The actual implementation of the feature.
===============

====================
Signed-off-by: David S. Miller <davem@davemloft.net>

Multiport eswitch mode is a LAG mode that allows to add rules that
forward traffic to a specific physical port without being affected by LAG
affinity configuration.

This mode of operation is mutual exclusive with the other LAG modes used
by multipath and bonding.

To make the transition between the modes, we maintain a counter on the
number of rules specifying one of the uplink representors as the target
of mirred egress redirect action.

An example of such rule would be:

$ tc filter add dev enp8s0f0_0 prot all root flower dst_mac \
  00:11:22:33:44:55 action mirred egress redirect dev enp8s0f0

If the reference count just grows to one and LAG is not in use, we
create the LAG in multiport eswitch mode. Other mode changes are not
allowed while in this mode. When the reference count reaches zero, we
destroy the LAG and let other modes be used if needed.

logic also changed such that if forwarding to some uplink destination
cannot be guaranteed, we fail the operation so the rule will eventually
be in software and not in hardware.
Signed-off-by: Eli Cohen <elic@nvidia.com>
Reviewed-by: Mark Bloch <mbloch@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>

Argument ndev is not used in mlx5_handle_changeupper_event()
Remove it.
Signed-off-by: Eli Cohen <elic@nvidia.com>
Reviewed-by: Mark Bloch <mbloch@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>

LAG state machine is implemented using bit flags. However, all these bit
flags, except for MLX5_LAG_FLAG_HASH_BASED, are really mutual exclusive.

In addition, MLX5_LAG_FLAG_READY is used by bonding to mark if we have
our netdevices successfully added to lag and does not really belong in
the same flags variable as the other flags.

Rename MLX5_LAG_FLAG_READY to MLX5_LAG_FLAG_NDEVS_READY to better
reflect its purpose and put it in a new flags variable.

For the rest of the flags, we introduce a mode enum to hold the state
of the LAG.

Remove the shared fdb boolean flag from struct mlx5_lag and store this
configuration as a mode flag.

Change all flag related operations to use standard Linux APIs.
Signed-off-by: Eli Cohen <elic@nvidia.com>
Reviewed-by: Mark Bloch <mbloch@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>

This patch adds the XDP SQs to the uplink representors steering tables
in swichdev mode and enables XDP usage on them.
Signed-off-by: Gal Pressman <gal@nvidia.com>
Reviewed-by: Maor Dickman <maord@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>

Correct the calculation of maximum channels of rep to better utilize
the hardware resources and allow a larger scale of reps.

This will allow creation of all virtual ports configured.

Fixes: 473baf2e ("net/mlx5e: Allow profile-specific limitation on max num of channels")
Signed-off-by: Moshe Tal <moshet@nvidia.com>
Reviewed-by: Tariq Toukan <tariqt@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>

Connection offload is translated to multiple rules over several
hardware flow tables. Unhandled end-cases may cause a hardware
resource leak causing multiple system symptoms such as a host
memory leak, decreased performance and other scale related issues.

Export the current number of firmware FTEs related to the CT table
as a debugfs counter. Also add a dropped packets counter to help
debug packets dropped on restore failure.

To show the offloaded count:
cat /sys/kernel/debug/mlx5/<PCI>/ct_nic/offloaded

To show the dropped count:
cat /sys/kernel/debug/mlx5/<PCI>/ct_nic/rx_dropped
Signed-off-by: Paul Blakey <paulb@mellanox.com>
Signed-off-by: Roi Dayan <paulb@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>
Reviewed-by: Oz Shlomo <ozsh@nvidia.com>
Reviewed-by: Paul Blakey <paulb@nvidia.com>

By PCI spec, the config space of the VF always report relaxed ordering
not supported while it inherits this property from its PF. Hence using
pcie_relaxed_ordering_enable(), always disables the relaxed ordering on
all VFs. Remove this check and rely on the firmware which queries the
config space of the PF and set the capability bit accordingly.
Signed-off-by: Aya Levin <ayal@nvidia.com>
Reviewed-by: Gal Pressman <gal@nvidia.com>
Reviewed-by: Marina Varshaver <marinav@nvidia.com>
Reviewed-by: Gal Shalom <galshalom@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>

Offloading outer checksum on tunnels requires GSO partial, add it to
'vlan_features' to allow offloading tunnels over vlans.
For example, running GENEVE over vlan & ipv6 (mandatory UDP checksum)
now allows for hardware TSO instead of software segmentation in GSO
only.
Signed-off-by: Gal Pressman <gal@nvidia.com>
Reviewed-by: Aya Levin <ayal@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>

Followup commit
79ce39be ("net/mlx5e: Improve ethtool rxnfc callback structure")
and handle CONFIG_MLX5_EN_RXNFC enabled/disabled inside the fs layer so
the ethtool callbacks are always available. The fs layer will provide
stubs when CONFIG_MLX5_EN_RXNFC is compiled out.
Signed-off-by: Gal Pressman <gal@nvidia.com>
Reviewed-by: Tariq Toukan <tariqt@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>

Physical continuity is not necessary, and requested allocation size might
be larger than PAGE_SIZE.
Hence, use v-alloc/free API.
Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
Reviewed-by: Moshe Shemesh <moshe@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>

Physical continuity is not necessary, and requested allocation size might
be larger than PAGE_SIZE.
Hence, use v-alloc/free API.
Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
Reviewed-by: Moshe Shemesh <moshe@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>

Physical continuity is not necessary, and requested allocation size might
be larger than PAGE_SIZE.
Hence, use v-alloc/free API.
Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
Reviewed-by: Moshe Shemesh <moshe@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>

Physical continuity is not necessary, and requested allocation size might
be larger than PAGE_SIZE.
Hence, use v-alloc/free API.
Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
Reviewed-by: Moshe Shemesh <moshe@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>

Take the wrapper version which picks default node into a header file.
This reduces the number of exported functions.
Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
Reviewed-by: Moshe Shemesh <moshe@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>

Add syndrome of last command failure per command type to debugfs to ease
debugging of such failure.
last_failed_syndrome - last command failed syndrome returned by FW.
Signed-off-by: Moshe Shemesh <moshe@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>

Removing the annotation resolves the issue for some reason.
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>

Added support for adaptive IRQ coalescing. It uses net_dim
algorithm to find the suitable delay/IRQ count based on the
current packet rate.
Signed-off-by: Suman Ghosh <sumang@marvell.com>
Link: https://lore.kernel.org/r/20220517044055.876158-1-sumang@marvell.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

Like other places in ipv4/6 dst ifdown, change to use blackhole_netdev
instead of pernet loopback_dev in dn dst ifdown.
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Link: https://lore.kernel.org/r/0cdf10e5a4af509024f08644919121fb71645bc2.1652751029.git.lucien.xin@gmail.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

Also removes PEROUT_ENABLE_OUTPUT_MASK
Signed-off-by: Min Li <min.li.xe@renesas.com>
Acked-by: Richard Cochran <richardcochran@gmail.com>
Link: https://lore.kernel.org/r/1652712427-14703-2-git-send-email-min.li.xe@renesas.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

Use TOD_READ_SECONDARY for extts to keep TOD_READ_PRIMARY
for gettime and settime exclusively. Before this change,
TOD_READ_PRIMARY was used for both extts and gettime/settime,
which would result in changing TOD read/write triggers between
operations. Using TOD_READ_SECONDARY would make extts
independent of gettime/settime operation
Signed-off-by: Min Li <min.li.xe@renesas.com>
Acked-by: Richard Cochran <richardcochran@gmail.com>
Link: https://lore.kernel.org/r/1652712427-14703-1-git-send-email-min.li.xe@renesas.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

Fix the following coccicheck warning:

drivers/net/ethernet/smsc/smc911x.c:483:20-22: WARNING opportunity for min()
Signed-off-by: Guo Zhengkui <guozhengkui@vivo.com>
Link: https://lore.kernel.org/r/20220516115627.66363-1-guozhengkui@vivo.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

container_of() will never return NULL, so remove useless code.
Signed-off-by: Haowen Bai <baihaowen@meizu.com>
Link: https://lore.kernel.org/r/1652696212-17516-1-git-send-email-baihaowen@meizu.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

Use memset_startat() helper to simplify the code, there is no functional
change in this patch.
Signed-off-by: Xiu Jianfeng <xiujianfeng@huawei.com>
Link: https://lore.kernel.org/r/20220516092337.131653-1-xiujianfeng@huawei.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

Guangguan Wang says:

====================
net/smc: send and write inline optimization for smc

Send cdc msgs and write data inline if qp has sufficent inline
space, helps latency reducing.

In my test environment, which are 2 VMs running on the same
physical host and whose NICs(ConnectX-4Lx) are working on
SR-IOV mode, qperf shows 0.4us-1.3us improvement in latency.

Test command:
server: smc_run taskset -c 1 qperf
client: smc_run taskset -c 1 qperf <server ip> -oo \
		msg_size:1:2K:*2 -t 30 -vu tcp_lat

The results shown below:
msgsize     before       after
1B          11.9 us      10.6 us (-1.3 us)
2B          11.7 us      10.7 us (-1.0 us)
4B          11.7 us      10.7 us (-1.0 us)
8B          11.6 us      10.6 us (-1.0 us)
16B         11.7 us      10.7 us (-1.0 us)
32B         11.7 us      10.6 us (-1.1 us)
64B         11.7 us      11.2 us (-0.5 us)
128B        11.6 us      11.2 us (-0.4 us)
256B        11.8 us      11.2 us (-0.6 us)
512B        11.8 us      11.3 us (-0.5 us)
1KB         11.9 us      11.5 us (-0.4 us)
2KB         12.1 us      11.5 us (-0.6 us)
====================

Link: https://lore.kernel.org/r/20220516055137.51873-1-guangguan.wang@linux.alibaba.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

Rdma write with inline flag when sending small packages,
whose length is shorter than the qp's max_inline_data, can
help reducing latency.

In my test environment, which are 2 VMs running on the same
physical host and whose NICs(ConnectX-4Lx) are working on
SR-IOV mode, qperf shows 0.5us-0.7us improvement in latency.

Test command:
server: smc_run taskset -c 1 qperf
client: smc_run taskset -c 1 qperf <server ip> -oo \
		msg_size:1:2K:*2 -t 30 -vu tcp_lat

The results shown below:
msgsize     before       after
1B          11.2 us      10.6 us (-0.6 us)
2B          11.2 us      10.7 us (-0.5 us)
4B          11.3 us      10.7 us (-0.6 us)
8B          11.2 us      10.6 us (-0.6 us)
16B         11.3 us      10.7 us (-0.6 us)
32B         11.3 us      10.6 us (-0.7 us)
64B         11.2 us      11.2 us (0 us)
128B        11.2 us      11.2 us (0 us)
256B        11.2 us      11.2 us (0 us)
512B        11.4 us      11.3 us (-0.1 us)
1KB         11.4 us      11.5 us (0.1 us)
2KB         11.5 us      11.5 us (0 us)
Signed-off-by: Guangguan Wang <guangguan.wang@linux.alibaba.com>
Reviewed-by: Tony Lu <tonylu@linux.alibaba.com>
Tested-by: kernel test robot <lkp@intel.com>
Acked-by: Karsten Graul <kgraul@linux.ibm.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

As cdc msg's length is 44B, cdc msgs can be sent inline in
most rdma devices, which can help reducing sending latency.

In my test environment, which are 2 VMs running on the same
physical host and whose NICs(ConnectX-4Lx) are working on
SR-IOV mode, qperf shows 0.4us-0.7us improvement in latency.

Test command:
server: smc_run taskset -c 1 qperf
client: smc_run taskset -c 1 qperf <server ip> -oo \
		msg_size:1:2K:*2 -t 30 -vu tcp_lat

The results shown below:
msgsize     before       after
1B          11.9 us      11.2 us (-0.7 us)
2B          11.7 us      11.2 us (-0.5 us)
4B          11.7 us      11.3 us (-0.4 us)
8B          11.6 us      11.2 us (-0.4 us)
16B         11.7 us      11.3 us (-0.4 us)
32B         11.7 us      11.3 us (-0.4 us)
64B         11.7 us      11.2 us (-0.5 us)
128B        11.6 us      11.2 us (-0.4 us)
256B        11.8 us      11.2 us (-0.6 us)
512B        11.8 us      11.4 us (-0.4 us)
1KB         11.9 us      11.4 us (-0.5 us)
2KB         12.1 us      11.5 us (-0.6 us)
Signed-off-by: Guangguan Wang <guangguan.wang@linux.alibaba.com>
Reviewed-by: Tony Lu <tonylu@linux.alibaba.com>
Tested-by: kernel test robot <lkp@intel.com>
Acked-by: Karsten Graul <kgraul@linux.ibm.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

As per Errata Section 5.1, if EEE is intended to be used, some register
writes must be done once after every hardware reset. This patch now adds
the necessary register writes as listed in the Marvell errata.

Without this fix we experience ethernet problems on some of our boards
equipped with a new version of this ethernet PHY (different supplier).

The fix applies to Marvell Alaska 88E1510/88E1518/88E1512/88E1514
Rev. A0.
Signed-off-by: Leszek Polak <lpolak@arri.de>
Signed-off-by: Stefan Roese <sr@denx.de>
Cc: Marek Behún <kabel@kernel.org>
Cc: Andrew Lunn <andrew@lunn.ch>
Cc: Heiner Kallweit <hkallweit1@gmail.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: David S. Miller <davem@davemloft.net>
Reviewed-by: Marek Behún <kabel@kernel.org>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Link: https://lore.kernel.org/r/20220516070859.549170-1-sr@denx.deSigned-off-by: Paolo Abeni <pabeni@redhat.com>

Calling synchronize_irq() right before free_irq() is quite useless. On one
hand the IRQ can easily fire again before free_irq() is entered, on the
other hand free_irq() itself calls synchronize_irq() internally (in a race
condition free way), before any state associated with the IRQ is freed.
Reported-by: Zeal Robot <zealci@zte.com.cn>
Signed-off-by: Minghao Chi <chi.minghao@zte.com.cn>
Link: https://lore.kernel.org/r/20220516082251.1651350-1-chi.minghao@zte.com.cnSigned-off-by: Paolo Abeni <pabeni@redhat.com>

Calling synchronize_irq() right before free_irq() is quite useless. On one
hand the IRQ can easily fire again before free_irq() is entered, on the
other hand free_irq() itself calls synchronize_irq() internally (in a race
condition free way), before any state associated with the IRQ is freed.
Reported-by: Zeal Robot <zealci@zte.com.cn>
Signed-off-by: Minghao Chi <chi.minghao@zte.com.cn>
Link: https://lore.kernel.org/r/20220516081914.1651281-1-chi.minghao@zte.com.cnSigned-off-by: Paolo Abeni <pabeni@redhat.com>

Calling synchronize_irq() right before free_irq() is quite useless. On one
hand the IRQ can easily fire again before free_irq() is entered, on the
other hand free_irq() itself calls synchronize_irq() internally (in a race
condition free way), before any state associated with the IRQ is freed.
Reported-by: Zeal Robot <zealci@zte.com.cn>
Signed-off-by: Minghao Chi <chi.minghao@zte.com.cn>
Link: https://lore.kernel.org/r/20220516072646.1651109-1-chi.minghao@zte.com.cnSigned-off-by: Paolo Abeni <pabeni@redhat.com>

Merge repeat codes to reduce the duplication.
Signed-off-by: Lu Wei <luwei32@huawei.com>
Link: https://lore.kernel.org/r/20220516062804.254742-1-luwei32@huawei.comSigned-off-by: Paolo Abeni <pabeni@redhat.com>

Use eth_zero_addr() to clear mac address instead of memset().
Signed-off-by: Lu Wei <luwei32@huawei.com>
Link: https://lore.kernel.org/r/20220516033343.329178-1-luwei32@huawei.comSigned-off-by: Paolo Abeni <pabeni@redhat.com>

devm_kfree check the pointer, there is no need to check before
devm_kfree call.
This change is to cleanup the code a bit.
Signed-off-by: Bernard Zhao <bernard@vivo.com>
Link: https://lore.kernel.org/r/20220516015208.6526-1-bernard@vivo.comSigned-off-by: Paolo Abeni <pabeni@redhat.com>

Removed unnecessary:

	select COMMON_CLK_SP7021
	select RESET_SUNPLUS
	select NVMEM_SUNPLUS_OCOTP

from Kconfig.
Reported-by: kernel test robot <yujie.liu@intel.com>
Signed-off-by: Wells Lu <wellslutw@gmail.com>
Link: https://lore.kernel.org/r/1652443036-24731-1-git-send-email-wellslutw@gmail.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

Merge tag 'linux-can-next-for-5.19-20220516' of git://git.kernel.org/pub/scm/linux/kernel/git/mkl/linux-can-next

Marc Kleine-Budde says:

====================
pull-request: can-next 2022-05-16

the first 2 patches are by me and target the CAN raw protocol. The 1st
removes an unneeded assignment, the other one adds support for
SO_TXTIME/SCM_TXTIME.

Oliver Hartkopp contributes 2 patches for the ISOTP protocol. The 1st
adds support for transmission without flow control, the other let's
bind() return an error on incorrect CAN ID formatting.

Geert Uytterhoeven contributes a patch to clean up ctucanfd's Kconfig
file.

Vincent Mailhol's patch for the slcan driver uses the proper function
to check for invalid CAN frames in the xmit callback.

The next patch is by Geert Uytterhoeven and makes the interrupt-names
of the renesas,rcar-canfd dt bindings mandatory.

A patch by my update the ctucanfd dt bindings to include the common
CAN controller bindings.

The last patch is by Akira Yokosawa and fixes a breakage the
ctucanfd's documentation.

* tag 'linux-can-next-for-5.19-20220516' of git://git.kernel.org/pub/scm/linux/kernel/git/mkl/linux-can-next:
  docs: ctucanfd: Use 'kernel-figure' directive instead of 'figure'
  dt-bindings: can: ctucanfd: include common CAN controller bindings
  dt-bindings: can: renesas,rcar-canfd: Make interrupt-names required
  can: slcan: slc_xmit(): use can_dropped_invalid_skb() instead of manual check
  can: ctucanfd: Let users select instead of depend on CAN_CTUCANFD
  can: isotp: isotp_bind(): return -EINVAL on incorrect CAN ID formatting
  can: isotp: add support for transmission without flow control
  can: raw: add support for SO_TXTIME/SCM_TXTIME
  can: raw: raw_sendmsg(): remove not needed setting of skb->sk
====================

Link: https://lore.kernel.org/r/20220516202625.1129281-1-mkl@pengutronix.deSigned-off-by: Jakub Kicinski <kuba@kernel.org>

Ricardo Martinez says:

====================
net: skb: Remove skb_data_area_size()

This patch series removes the skb_data_area_size() helper,
replacing it in t7xx driver with the size used during skb allocation.

https://lore.kernel.org/netdev/CAHNKnsTmH-rGgWi3jtyC=ktM1DW2W1VJkYoTMJV2Z_Bt498bsg@mail.gmail.com/
====================

Link: https://lore.kernel.org/r/20220513173400.3848271-1-ricardo.martinez@linux.intel.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

skb_data_area_size() is not needed. As Jakub pointed out [1]:
For Rx, drivers can use the size passed during skb allocation or
use skb_tailroom().
For Tx, drivers should use skb_headlen().

[1] https://lore.kernel.org/netdev/CAHNKnsTmH-rGgWi3jtyC=ktM1DW2W1VJkYoTMJV2Z_Bt498bsg@mail.gmail.com/Signed-off-by: Ricardo Martinez <ricardo.martinez@linux.intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Sergey Ryazanov <ryazanov.s.a@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>