Jeff Kirsher says:

====================
100GbE Intel Wired LAN Driver Updates 2016-07-20

This series contains updates to fm10k only.

Ngai-Mint provides a fix to clear PCIE_GMBX bits to ensure the proper
functioning of the mailbox global interrupt after a data path reset.

Jake provides most of the patches in the series, starting with a early
return from fm10k_down() if we are already down to prevent conflict with
other threads.  Fixed an issue where fm10k_update_stats() could cause
a null pointer dereference, specifically if it is called when we are going
down and the rings have been removed.  Cleans up and fixes the data path
reset flow, Tx hang routine and stop_hw().  Re-worked the fm10k_reinit()
to be more maintainable and fixed several inconsistencies with the work
flow.  Implemented fm10k_prepare_suspend() and fm10k_handle_resume()
which abstract around the now existing fm10k_prepare_for_reset and
fm10k_handle_reset. The new functions also handle stopping the service
task, which is something that the original re-init flow does not need.
Fixed an issue where if an FLR occurs, VF devices will be knocked out of
bus master mode, and the driver will be unable to recover from the reset
properly, so ensure bus master is enabled after every reset.  Fixed an
issue where a reset will occur as if for no reason, regularly every few
minutes until the switch manager software is loaded, which is caused
by continuously requesting the lport map so only do the request after
we have verified the switch mailbox is tx_ready.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

Vivien Didelot says:

====================
net: dsa: mv88e6xxx: rework EEPROM code

Some switches can access an optional external EEPROM via its registers.

The 88E6352 family of switches have 8-bit address / 16-bit data access.
The new 88E6390 family has 16-bit address / 8-bit data access.

This patchset cleans up the EEPROM code with 16-suffixed Global2 helpers
and makes it easy to add future support for 8-bit data EEPROM access.

It also removes unnecessary mutexes and a few locked access functions.

Changes in v2:
  - add missing Signed-off-by tag
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

Get rid of the last usage of the locked mv88e6xxx_reg_read function with
a new mv88e6xxx_port_read helper, useful later for chips with different
port registers base address.
Signed-off-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

The 6352 family of switches and compatibles provide a 8-bit address and
16-bit data access to an optional EEPROM.

Newer chip such as the 6390 family slightly changed the access to 16-bit
address and 8-bit data.

This commit cleans up the EEPROM access code for 16-bit access and makes
it easy to eventually introduce future support for 8-bit access.

Here's a list of notable changes brought by this patch:

  - provide Global2 unlocked helpers for EEPROM commands
  - remove eeprom_mutex, only reg_lock is necessary for driver functions
  - eeprom_len is 0 for chip without EEPROM, so return it directly
  - the Running bit must be 0 before r/w, so wait for Busy *and* Running
  - remove now unused mv88e6xxx_wait and mv88e6xxx_reg_write
  - other than that, the logic (in _{get,set}_eeprom16) didn't change

Chips with an 8-bit EEPROM access will require to implement the
8-suffixed variant of G2 helpers and the related flag:

    #define MV88E6XXX_FLAGS_EEPROM8	\
    	(MV88E6XXX_FLAG_G2_EEPROM_CMD |	\
    	 MV88E6XXX_FLAG_G2_EEPROM_ADDR)
Signed-off-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

Only reg_lock is necessary now and phy_mutex is dead. Remove it.
Signed-off-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

The initial MAC address is retrieved from hardware if it's not
provided by device-tree. The reserved MAC address from hardware
will be used if non-reserved MAC address is invalid. It will
cause mismatched MAC address seen by hardware and software.

This disallows using the reserved hardware MAC address to avoid
the mismatched MAC address seen by hardware and software.

Fixes: 113ce107 ("net/faraday: Read MAC address from chip")
Suggested-by: David Laight <David.Laight@ACULAB.COM>
Suggested-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Krishneil Singh <Krishneil.k.singh@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

The pci_enable_msix_range() function returns a positive value of the
number of allocated vectors if it succeeds. On failure it returns
a negative error code. Return this code properly so that the error
message printed by the driver will show the actual error code instead of
being masked by -ENOMEM.
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Krishneil Singh <Krishneil.k.singh@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

When we resume from an AER recovery with many active VFs, the PF sees
many spurious link up and link down events. Prevent this by delaying
link down for at least one second after the resume event.
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Krishneil Singh <Krishneil.k.singh@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

If the fm10k interface is brought up, but the switch manager software is
not running, the driver will continuously request the lport map every
few seconds in the base driver watchdog routine. Eventually after
several minutes the switch mailbox Tx fifo will fill up and the mailbox
will timeout, resulting in a reset. This reset will appear as if for no
reason, and occurs regularly every few minutes until the switch manager
software is loaded.

Prevent this from happening by only requesting the lport map after we've
verified the switch mailbox is tx_ready. In order to simplify code logic
and reduce code duplication, implement this as a new function pointer
"mac.ops.request_lport_map" which the VF will not implement. Otherwise,
we have to duplicate the tx_ready check outside of
fm10k_get_host_state_generic, or re-implement most of
fm10k_get_host_state_generic in the pf version.

The resulting code is simpler and easier to understand, and prevents the
PF from continuously requesting lport map and filling the Tx fifo of
a switch mailbox that isn't ready.
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Krishneil Singh <Krishneil.k.singh@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

Sometimes, a VF driver will lose PCIe address access, such as due to
a PF FLR event. In fm10k_detach_subtask, poll and check whether the
PCIe register space is active again and restore the device when it has.
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Krishneil Singh <Krishneil.k.singh@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

If an FLR occurs, VF devices will be knocked out of bus master mode, and
the driver will be unable to recover from the reset properly, resulting
in malicious driver events and an infinite reset loop. In the normal
case, the bus master mode will already be enabled and this call will
essentially be a no-op. Since we're doing this every reset, it is
possible we could remove the other calls to pci_set_master() but it
seems not harmful to just leave them in place.
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Krishneil Singh <Krishneil.k.singh@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

Continuing the effort to commonize the similar suspend/resume flows,
finish up by using the new fm10k_handle_suspand and fm10k_handle_resume
functions for the standard suspend/resume flow.
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Krishneil Singh <Krishneil.k.singh@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

When a function level PCI reset is triggered using sysfs, it calls the
driver's .reset_notify error handler. Implement a handler based on the
now split fm10k_prepare_for_reset and fm10k_handle_reset functions, so
that we fully reset the driver when the PCI function level reset occurs.
This also ensures the reset is handled in a clean way by first disabling
all the driver bits first and then restoring them after the function
reset. Previously the stack simply performed a blind function reset and
our driver didn't take any part in the process.
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Krishneil Singh <Krishneil.k.singh@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

Now that we have extracted the necessary steps for a split
suspend/resume flow, re-use these functions instead of using the current
open coded flow. This ensures that we don't miss any steps. It also
ensures that we have the correct driver states set.

Since we'll be handling all of the reset flow ourselves, we no longer
need to request a reset in the io_slot_reset() function.
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Krishneil Singh <Krishneil.k.singh@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

Implement fm10k_prepare_suspend and fm10k_handle_resume functions which
abstract around the now existing fm10k_prepare_for_reset and
fm10k_handle_reset. The new functions also handle stopping the service
task, which is something that the original re-init flow does not need.

Every other location that does a suspend/resume type flow is expected to
use these functions, because otherwise they may have conflicts with the
running watchdog routines. This also has the effect of preventing
possible surprise remove events during handling of FLR events and PCIe
errors.
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Krishneil Singh <Krishneil.k.singh@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

There are several flows in the driver which perform the similar function
of tearing down software and restoring software to recover from certain
errors or PCIe events, including:

  * fm10k_reinit
  * fm10k_suspend/resume
  * fm10k_io_error_detected/fm10k_io_resume

In addition, we want to implement a .reset_notify() handler as well
which will also perform similar function.

Rework how the driver codes reset and resume flows by separating out the
reinit logic into two functions "fm10k_prepare_for_reset" and
"fm10k_handle_reset". This first step will allow us to re-use this
functionality in the similar blocks of code instead of re-coding the
same sequence of events slightly different.

The end result should be more maintainable and correct, fixing several
inconsistencies with the work flow.

The new functions expect to take the rtnl_lock() themselves, and it does
have the unfortunate side effect of having the reinit flow take then
release then take the rtnl_lock. However, this minor downside is
out weighted by the benefits of code reduction and reducing needless
difference between these flows.
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Krishneil Singh <Krishneil.k.singh@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

It turns out that sometimes during a reset the Tx queues will be
temporarily stuck longer than .stop_hw() expects. Work around this issue
by attempting to .stop_hw() first. If it tails, wait a number of
attempts until the Tx queues appear to be drained. After this, attempt
stop_hw() again. This ensures that we avoid waiting if we don't need to,
such as during the first initialization of a VF, and give the proper
amount of time necessary to recover from most situations. It is possible
that the hardware is actually stuck. For PFs, this is usually fixed by
a datapath reset. Unfortunately the VF cannot request a similar reset
for itself.
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Krishneil Singh <Krishneil.k.singh@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

When stop_hw() routine fails with FM10K_ERR_REQUESTS_PENDING, this
indicates that the Tx or Rx queues did not shutdown within the time
limit. Print a more suitable message at the dev_info level instead of
dev_err.
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Krishneil Singh <Krishneil.k.singh@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Krishneil Singh <Krishneil.k.singh@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

A while ago, an additional check for the switch being ready was added to
reset_hw. A recent refactor accidentally made this check return an error
code on failure which caused fm10k_probe to fail when the switch wasn't
brought up first. The original reasoning for the check was to prevent
additional data path reset when the fabric wasn't ready yet. However,
there isn't a compelling reason to keep the check, as the data path
reset will restore hardware to a known good state. Remove the check and
perform the data path reset regardless of the switch manager state.

An alternative fix is to return FM10K_SUCCESS instead, and bypass the
actual data path reset. This should be fine as we will perform
a reset_hw once the switch is active. However, since data path reset
will reset many parts of the hardware it seems better to just perform
the reset regardless of switch state.
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Krishneil Singh <Krishneil.k.singh@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

Don't report FM10K_ERR_REQUESTS_PENDING when we fail to disable queues
within the timeout. This can occur due to a hardware Tx hang, or when
the switch ethernet fabric is resetting while we are transmitting
traffic. It can sometimes take up to 500ms before the Tx DMA engine
gives up. Instead, just skip the DMA engine check and perform
a data-path reset anyways. Add a statistic counter to keep track of the
number of resets occurring while we have pending DMA on the rings.

In order to prevent having to re-assign err to 0, re-order the
last few items of the reset_hw_pf function so that we don't perform
"return err" at the end.
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Krishneil Singh <Krishneil.k.singh@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

When a data path reset is initiated, write control to the PCIE_GMBX is
yanked from the switch manager. The switch manager writes to this
register to clear mailbox global interrupt bits as part of its mailbox
interrupt handling routine. When the device recovers from the data path
reset and these bits are not cleared, it will prevent future mailbox
global interrupts from being triggered. Upon confirming that the device
has exited from a data path reset, clear these bits to ensure the proper
functioning of the mailbox global interrupt.
Signed-off-by: Ngai-Mint Kwan <ngai-mint.kwan@intel.com>
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Krishneil Singh <Krishneil.k.singh@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

Also prevent updating stats while the interface is down. If we're
already updating stats, just return doing nothing. When we take the
device down, block stat updates until we come back up. This ensures that
we avoid tearing down rings when we're updating statistics, and prevents
updating statistics until we're up.

We can't re-use the __FM10K_DOWN for this because it wouldn't prevent
multiple threads from accessing statistics. Neither does it prevent the
case where we start updating stats and then start going down in another
thread.

The fm10k_get_stats64 is except from this, because it has a completely
different flow which does not suffer from the same issues as
fm10k_update_stats might.
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Krishneil Singh <Krishneil.k.singh@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

It's currently possible for fm10k_update_stats to be called during the
window when we go down and the rings are removed. This can result in
a null pointer dereference. In fm10k_get_stats64 we work around this by
using ACCESS_ONCE and a null pointer check inside the loop. Use this
same flow in the fm10k_update_stats to avoid the potential null pointer.
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Krishneil Singh <Krishneil.k.singh@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

Return early from fm10k_down() when we are already down, since that
means another thread is either already finished or has started going
down, so shouldn't conflict with them.
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Krishneil Singh <Krishneil.k.singh@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

Jiri Pirko says:

====================
mlxsw: Add per-{Prio,TC} counters

Ido says:

Add per-priority and per-tc counters, which are very useful for debugging
purposes and fine-tuning.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

Expose the transmit queue length of each traffic class and the amount of
unicast packets discarded due to insufficient room in the shared buffer.

The first counter allows us to debug user priority to traffic class
mapping, whereas the drop counter is useful when determining shared buffer
configuration.
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Expose per-priority bytes / packets / PFC packets counters via ethtool.

These counters are very useful when debugging QoS functionality and
provide a better insight into the device's forwarding plane.
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Add the missing free_netdev() before return from function
cpmac_probe() in the error handling case.
This patch revert commit 0465be8f ("net: cpmac: fix in
releasing resources"), which changed to only free_netdev
while register_netdev failed.
Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Signed-off-by: David S. Miller <davem@davemloft.net>

Use PTR_ERR_OR_ZERO rather than if(IS_ERR(...)) + PTR_ERR.

Generated by: scripts/coccinelle/api/ptr_ret.cocci
Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Acked-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

In ops->reset() error handling case, clk_disable_unprepare() is missed
before return from this function.
Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Acked-by: Mans Rullgard <mans@mansr.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

module_platform_driver() makes the code simpler by eliminating
boilerplate code.
Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Signed-off-by: David S. Miller <davem@davemloft.net>

Remove .owner field if calls are used which set it automatically.

Generated by: scripts/coccinelle/api/platform_no_drv_owner.cocci
Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Signed-off-by: David S. Miller <davem@davemloft.net>

In case of error, the function of_parse_phandle() returns NULL
pointer not ERR_PTR(). The IS_ERR() test in the return value
check should be replaced with NULL test.

Fixes: 46aa27df ('net: axienet: Use devm_* calls')
Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Signed-off-by: David S. Miller <davem@davemloft.net>

Merge branch 'for-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/bluetooth/bluetooth-next

Johan Hedberg says:

====================
pull request: bluetooth-next 2016-07-19

Here's likely the last bluetooth-next pull request for the 4.8 kernel:

 - Fix for L2CAP setsockopt
 - Fix for is_suspending flag handling in btmrvl driver
 - Addition of Bluetooth HW & FW info fields to debugfs
 - Fix to use int instead of char for callback status.

The last one (from Geert Uytterhoeven) is actually not purely a
Bluetooth (or 802.15.4) patch, but it was agreed with other maintainers
that we take it through the bluetooth-next tree.

Please let me know if there are any issues pulling. Thanks.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

Add the official BPF ELF e_machine value that was assigned recently [1,2]
and will be propagated to glibc, et al. LLVM is switching to it in 3.9
release.

  [1] https://github.com/llvm-mirror/llvm/commit/36b9c09330bfb5e771914cfe307588f30d5510d2
  [2] http://lists.iovisor.org/pipermail/iovisor-dev/2016-June/000266.htmlSigned-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

For the ifndef case of CONFIG_BPF_SYSCALL, an inline version of
bpf_prog_add needs to exist otherwise the build breaks on some configs.

 drivers/net/ethernet/mellanox/mlx4/en_netdev.c:2544:10: error: implicit declaration of function 'bpf_prog_add'
       prog = bpf_prog_add(prog, priv->rx_ring_num - 1);

The function is introduced in
59d3656d ("bpf: add bpf_prog_add api for bulk prog refcnt")
and first used in
47f1afdba2b87 ("net/mlx4_en: add support for fast rx drop bpf program").

Fixes: 47f1afdba2b87 ("net/mlx4_en: add support for fast rx drop bpf program")
Reported-by: kbuild test robot <fengguang.wu@intel.com>
Reported-by: Tariq Toukan <ttoukan.linux@gmail.com>
Signed-off-by: Brenden Blanco <bblanco@plumgrid.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

Brenden Blanco says:

====================
Add driver bpf hook for early packet drop and forwarding

This patch set introduces new infrastructure for programmatically
processing packets in the earliest stages of rx, as part of an effort
others are calling eXpress Data Path (XDP) [1]. Start this effort by
introducing a new bpf program type for early packet filtering, before
even an skb has been allocated.

Extend on this with the ability to modify packet data and send back out
on the same port.

Patch 1 adds an API for bulk bpf prog refcnt incrememnt.
Patch 2 introduces the new prog type and helpers for validating the bpf
  program. A new userspace struct is defined containing only data and
  data_end as fields, with others to follow in the future.
In patch 3, create a new ndo to pass the fd to supported drivers.
In patch 4, expose a new rtnl option to userspace.
In patch 5, enable support in mlx4 driver.
In patch 6, create a sample drop and count program. With single core,
  achieved ~20 Mpps drop rate on a 40G ConnectX3-Pro. This includes
  packet data access, bpf array lookup, and increment.
In patch 7, add a page recycle facility to mlx4 rx, enabled when xdp is
  active.
In patch 8, add the XDP_TX type to bpf.h
In patch 9, add helper in tx patch for writing tx_desc
In patch 10, add support in mlx4 for packet data write and forwarding
In patch 11, turn on packet write support in the bpf verifier
In patch 12, add a sample program for packet write and forwarding. With
  single core, achieved ~10 Mpps rewrite and forwarding.

[1] https://github.com/iovisor/bpf-docs/blob/master/Express_Data_Path.pdf

v10:
 1/12: Add bulk refcnt api.
 5/12: Move prog from priv to ring. This attribute is still only set
   globally, but the path to finer granularity should be clear. No lock
   is taken, so some rings may operate on older programs for a time (one
   napi loop). Looked into options such as napi_synchronize, but they
   were deemed too slow (calls to msleep).
   Rename prog to xdp_prog. Add xdp_ring_num to help with accounting,
   used more heavily in later patches.
 7/12: Adjust to use per-ring xdp prog. Use priv->xdp_ring_num where
   before priv->prog was used to determine buffer allocations.
 9/12: Add cpu_to_be16 to vlan_tag in mxl4_en_xmit(). Remove unused variable
   from mlx4_en_xmit and unused params from build_inline_wqe.

v9:
 4/11: Add missing newline in en_err message.
 6/11: Move page_cache cleanup from mlx4_en_destroy_rx_ring to
   mlx4_en_deactivate_rx_ring. Move mlx4_en_moderation_update back to
   static. Remove calls to mlx4_en_alloc/free_resources in mlx4_xdp_set.
   Adopt instead the approach of mlx4_en_change_mtu to use a watchdog.
 9/11: Use a per-ring function pointer in tx to separate out the code
   for regular and recycle paths of tx completion handling. Add a helper
   function to init the recycle ring and callback, called just after
   activating tx. Remove extra tx ring resource requirement, and instead
   steal from the upper rings. This helps to avoid needing
   mlx4_en_alloc_resources. Add some hopefully meaningful error
   messages for the various error cases. Reverted some of the
   hard-to-follow logic that was accounting for the extra tx rings.

v8:
 1/11: Reduce WARN_ONCE to single line. Also, change act param of that
   function to u32 to match return type of bpf_prog_run_xdp.
 2/11: Clarify locking semantics in ndo comment.
 4/11: Add en_err warning in mlx4_xdp_set on num_frags/mtu violation.

v7:
 Addressing two of the major discussion points: return codes and ndo.
 The rest will be taken as todo items for separate patches.

 Add an XDP_ABORTED type, which explicitly falls through to DROP. The
 same result must be taken for the default case as well, as it is now
 well-defined API behavior.

 Merge ndo_xdp_* into a single ndo. The style is similar to
 ndo_setup_tc, but with less unidirectional naming convention. The IFLA
 parameter names are unchanged.

 TODOs:
 Add ethtool per-ring stats for aborted, default cases, maybe even drop
 and tx as well.
 Avoid duplicate dma sync operation in XDP_PASS case as mentioned by
 Saeed.

  1/12: Add XDP_ABORTED enum, reword API comment, and update commit
   message.
  2/12: Rewrite ndo_xdp_*() into single ndo_xdp() with type/union style
    calling convention.
  3/12: Switch to ndo_xdp callback.
  4/12: Add XDP_ABORTED case as a fall-through to XDP_DROP. Implement
    ndo_xdp.
 12/12: Dropped, this will need some more work.

v6:
  2/12: drop unnecessary netif_device_present check
  4/12, 6/12, 9/12: Reorder default case statement above drop case to
    remove some copy/paste.

v5:
  0/12: Rebase and remove previous 1/13 patch
  1/12: Fix nits from Daniel. Left the (void *) cast as-is, to be fixed
    in future. Add bpf_warn_invalid_xdp_action() helper, to be used when
    out of bounds action is returned by the program. Add a comment to
    bpf.h denoting the undefined nature of out of bounds returns.
  2/12: Switch to using bpf_prog_get_type(). Rename ndo_xdp_get() to
    ndo_xdp_attached().
  3/12: Add IFLA_XDP as a nested type, and add the associated nla_policy
    for the new subtypes IFLA_XDP_FD and IFLA_XDP_ATTACHED.
  4/12: Fixup the use of READ_ONCE in the ndos. Add a user of
    bpf_warn_invalid_xdp_action helper.
  5/12: Adjust to using the nested netlink options.
  6/12: kbuild was complaining about overflow of u16 on tile
    architecture...bump frag_stride to u32. The page_offset member that
    is computed from this was already u32.

v4:
  2/12: Add inline helper for calling xdp bpf prog under rcu
  3/12: Add detail to ndo comments
  5/12: Remove mlx4_call_xdp and use inline helper instead.
  6/12: Fix checkpatch complaints
  9/12: Introduce new patch 9/12 with common helper for tx_desc write
    Refactor to use common tx_desc write helper
 11/12: Fix checkpatch complaints

v3:
  Rewrite from v2 trying to incorporate feedback from multiple sources.
  Specifically, add ability to forward packets out the same port and
    allow packet modification.
  For packet forwarding, the driver reserves a dedicated set of tx rings
    for exclusive use by xdp. Upon completion, the pages on this ring are
    recycled directly back to a small per-rx-ring page cache without
    being dma unmapped.
  Use of the percpu skb is dropped in favor of a lightweight struct
    xdp_buff. The direct packet access feature is leveraged to remove
    dependence on the skb.
  The mlx4 driver implementation allocates a page-per-packet and maps it
    in PCI_DMA_BIDIRECTIONAL mode when the bpf program is activated.
  Naming is converted to use "xdp" instead of "phys_dev".

v2:
  1/5: Drop xdp from types, instead consistently use bpf_phys_dev_
    Introduce enum for return values from phys_dev hook
  2/5: Move prog->type check to just before invoking ndo
    Change ndo to take a bpf_prog * instead of fd
    Add ndo_bpf_get rather than keeping a bool in the netdev struct
  3/5: Use ndo_bpf_get to fetch bool
  4/5: Enforce that only 1 frag is ever given to bpf prog by disallowing
    mtu to increase beyond FRAG_SZ0 when bpf prog is running, or conversely
    to set a bpf prog when priv->num_frags > 1
    Rename pseudo_skb to bpf_phys_dev_md
    Implement ndo_bpf_get
    Add dma sync just before invoking prog
    Check for explicit bpf return code rather than nonzero
    Remove increment of rx_dropped
  5/5: Use explicit bpf return code in example
    Update commit log with higher pps numbers
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

Add a sample that rewrites and forwards packets out on the same
interface. Observed single core forwarding performance of ~10Mpps.

Since the mlx4 driver under test recycles every single packet page, the
perf output shows almost exclusively just the ring management and bpf
program work. Slowdowns are likely occurring due to cache misses.
Signed-off-by: Brenden Blanco <bblanco@plumgrid.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>