commit 7a0adc83 ("ath10k: improve tx scheduling") is causing
severe throughput drop in multi client mode. This issue is originally
reported in veriwave setup with 50 clients with TCP downlink traffic.
While increasing number of clients, the average throughput drops
gradually. With 50 clients, the combined peak throughput is decreased
to 98 Mbps whereas reverting given commit restored it to 550 Mbps.

Processing txqs for every tx completion is causing overhead. Ideally for
management frame tx completion, pending txqs processing can be avoided.
The change partly reverts the commit "ath10k: improve tx scheduling".
Processing pending txqs after all skbs tx completion will yeild enough
room to burst tx frames.

Fixes: 7a0adc83 ("ath10k: improve tx scheduling")
Signed-off-by: Rajkumar Manoharan <rmanohar@qti.qualcomm.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>

Add NAPI support for rx and tx completion. NAPI poll is scheduled
from interrupt handler. The design is as below

 - on interrupt
     - schedule napi and mask interrupts
 - on poll
   - process all pipes (no actual Tx/Rx)
   - process Rx within budget
   - if quota exceeds budget reschedule napi poll by returning budget
   - process Tx completions and update budget if necessary
   - process Tx fetch indications (pull-push)
   - push any other pending Tx (if possible)
   - before resched or napi completion replenish htt rx ring buffer
   - if work done < budget, complete napi poll and unmask interrupts

This change also get rid of two tasklets (intr_tq and txrx_compl_task).

Measured peak throughput with NAPI on IPQ4019 platform in controlled
environment. No noticeable reduction in throughput is seen and also
observed improvements in CPU usage. Approx. 15% CPU usage got reduced
in UDP uplink case.

DL: AP DUT Tx
UL: AP DUT Rx

IPQ4019 (avg. cpu usage %)

========
                TOT              +NAPI
              ===========      =============
TCP DL       644 Mbps (42%)    645 Mbps (36%)
TCP UL       673 Mbps (30%)    675 Mbps (26%)
UDP DL       682 Mbps (49%)    680 Mbps (49%)
UDP UL       720 Mbps (28%)    717 Mbps (11%)
Signed-off-by: Rajkumar Manoharan <rmanohar@qti.qualcomm.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>

We get 1 warning about global functions without a declaration
in the ath9k gpio driver when building with W=1:
drivers/net/wireless/ath/ath9k/gpio.c:25:6: warning: no previous prototype for 'ath_fill_led_pin' [-Wmissing-prototypes]

In fact, this function is only used in the file in which it is declared
and don't need a declaration, but can be made static.
so this patch marks it 'static'.
Signed-off-by: Baoyou Xie <baoyou.xie@linaro.org>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>

Trivial fix to spelling mistake in ath10k_warn message.
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Reviewed-by: Julian Calaby <julian.calaby@gmail.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>

Older firmware with HTT delivers incorrect tx status for null func
frames to driver, but this fixed in 10.2 and 10.4 firmware versions.
Also this workaround results in reporting of incorrect null func status
for 10.4. Fix this is by introducing a firmware feature flag for 10.4
so that this workaround is skipped and proper tx status for null func
frames are reported
Signed-off-by: Tamizh chelvam <c_traja@qti.qualcomm.com>
Signed-off-by: Mohammed Shafi Shajakhan <mohammed@qti.qualcomm.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>

Commit 97f2645f ("tree-wide: replace config_enabled() with
IS_ENABLED()") mostly did away with config_enabled().

This is one of the postponed TODO items as config_enabled() is used
for a tristate option here.  Theoretically, config_enabled() is
equivalent to IS_BUILTIN(), but I guess IS_REACHABLE() is the best
fit for this case because both CONFIG_HWMON and CONFIG_ATH10K are
tristate.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>

For 10.4 fw versions, dbglog module id has been extended from u32
to u64, hence this patch fixes the same in the ath10k driver side.

This patch doesn't break the older 10.4 releases. The FW change
is already present in the older FWs.
Signed-off-by: Maharaja Kennadyrajan <c_mkenna@qti.qualcomm.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>

There is only one waiter for the completion, therefore there
is no need to use complete_all(). Let's make that clear by
using complete() instead of complete_all().

The usage pattern of the completion is:

waiter context                          waker context

scan.started
------------

ath10k_start_scan()
  lockdep_assert_held(conf_mutex)
  auth10k_wmi_start_scan()
  wait_for_completion_timeout(scan.started)

					ath10k_wmi_event_scan_start_failed()
					  complete(scan.started)

					ath10k_wmi_event_scan_started()
					  complete(scan.started)

scan.completed
--------------

ath10k_scan_stop()
  lockdep_assert_held(conf_mutex)
  ath10k_wmi_stop_scan()
  wait_for_completion_timeout(scan.completed)

					__ath10k_scan_finish()
					  complete(scan.completed)

scan.on_channel
---------------

ath10k_remain_on_channel()
  mutex_lock(conf_mutex)
  ath10k_start_scan()
  wait_for_completion_timeout(scan.on_channel)

					ath10k_wmi_event_scan_foreign_chan()
					  complete(scan.on_channel)

offchan_tx_completed
--------------------

ath10k_offchan_tx_work()
  mutex_lock(conf_mutex)
  reinit_completion(offchan_tx_completed)
  wait_for_completion_timeout(offchan_tx_completed)

					ath10k_report_offchain_tx()
					  complete(offchan_tx_completed)

install_key_done
----------------
ath10k_install_key()
  lockep_assert_held(conf_mutex)
  reinit_completion(install_key_done)
  wait_for_completion_timeout(install_key_done)

				        ath10k_htt_t2h_msg_handler()
					  complete(install_key_done)

vdev_setup_done
---------------

ath10k_monitor_vdev_start()
  lockdep_assert_held(conf_mutex)
   reinit_completion(vdev_setup_done)
  ath10k_vdev_setup_sync()
    wait_for_completion_timeout(vdev_setup_done)

					ath10k_wmi_event_vdev_start_resp()
					  complete(vdev_setup_done)

ath10k_monitor_vdev_stop()
  lockdep_assert_held(conf_mutex)
  reinit_completion(vdev_setup_done()
  ath10k_vdev_setup_sync()
    wait_for_completion_timeout(vdev_setup_done)

					ath10k_wmi_event_vdev_stopped()
					 complete(vdev_setup_done)

thermal.wmi_sync
----------------
ath10k_thermal_show_temp()
  mutex_lock(conf_mutex)
  reinit_completion(thermal.wmi_sync)
  wait_for_completion_timeout(thermal.wmi_sync)

					ath10k_thermal_event_temperature()
					  complete(thermal.wmi_sync)

bss_survey_done
---------------
ath10k_mac_update_bss_chan_survey
  lockdep_assert_held(conf_mutex)
  reinit_completion(bss_survey_done)
  wait_for_completion_timeout(bss_survey_done)

					ath10k_wmi_event_pdev_bss_chan_info()
					  complete(bss_survey_done)

All complete() calls happen while the conf_mutex is taken. That means
at max one waiter is possible.
Signed-off-by: Daniel Wagner <daniel.wagner@bmw-carit.de>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>

In the wake tx queue path, we are not checking if the frame to be sent
takes management path or not. For eg. QOS null func frame coming here will
take the management path. Since we are not incrementing the descriptor
counter (num_pending_mgmt_tx) w.r.t tx management, on tx completion it is
possible to see negative values.

When the above counter reaches a negative value, we will not be sending a
probe response out.

    if (is_presp &&
	ar->hw_params.max_probe_resp_desc_thres < htt->num_pending_mgmt_tx)

For IPQ4019, max_probe_resp_desc_thres (u32) is 24 is compared against
num_pending_mgmt_tx (int) and the above condtions comes true if the counter
is negative and we drop the probe response.

To avoid this, check on the wake tx queue path as well for the tx path of
the frame and increment the appropriate counters

Fixes: cac08552 "ath10k: move mgmt descriptor limit handle under mgmt_tx"
Signed-off-by: Ashok Raj Nagarajan <arnagara@qti.qualcomm.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>

txqs_lock is interfering with wake_tx_queue submitting more frames.
so queues don't get filled in and don't keep firmware/hardware busy
enough. This change helps to reduce the txqs_lock contention and
wake_tx_queue() blockage to being possible in txrx_unref().

To reduce turn around time of wake_tx_queue ops and to maintain fairness
among all txqs, the callback is updated to push first txq alone from
pending list for every wake_tx_queue call. Remaining txqs will be
processed later upon tx completion.

Below improvements are observed in push-only mode and validated on
IPQ4019 platform. With this change, in AP mode ~10Mbps increase is
observed in downlink (AP -> STA) traffic and approx. 5-10% of CPU
usage is reduced.

Major improvement is observed in 1-hop Mesh mode topology in 11ACVHT80.
Compared to Infra mode, CPU overhead is higher in Mesh mode due to path
lookup and no fast-xmit support. So reducing spin lock contention is
helping in Mesh.

             TOT       +change
           --------    --------
TCP DL     545 Mbps    595 Mbps
TCP UL     555 Mbps    585 Mbps
Signed-off-by: Rajkumar Manoharan <rmanohar@qti.qualcomm.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>

'WMI_10_4_WDS_PEER_EVENTID' is not yet handled/implemented for WDS mode,
as of now suppress the warning message "Unknown eventid: 36903"
Signed-off-by: Mohammed Shafi Shajakhan <mohammed@qti.qualcomm.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>

Recent commit 46f6b060 ("mac80211: Encrypt "Group addressed privacy" action
frames") encrypts group privacy action frames. But qca99x0 family chipset
delivers broadcast/multicast management frames as encrypted and it should be
decrypted by mac80211. Setting RX_FLAG_DECRYPTED stats for those frames is
breaking mesh connection establishment.
Signed-off-by: Rajkumar Manoharan <rmanohar@qti.qualcomm.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>

With the %pK format specifier we hide the kernel addresses
with the help of kptr_restrict sysctl.
In this patch, %p is changed to %pK in the driver code.

The sysctl is documented in Documentation/sysctl/kernel.txt.
Signed-off-by: Maharaja Kennadyrajan <c_mkenna@qti.qualcomm.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>

WMI_SERVICE_PERIODIC_CHAN_STAT_SUPPORT service has missed in
the commit 7e247a9e ("ath10k: add dynamic tx mode switch
config support for qca4019"). This patch adds the service to
avoid mismatch between host and target.

Fixes: 7e247a9e ("ath10k: add dynamic tx mode switch config support for qca4019")
Signed-off-by: Tamizh chelvam <c_traja@qti.qualcomm.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>

Currently the FW version is taken from the sw_version field
of the FW ready event. This version is based on internal
version control revision and it is difficult to map to actual
FW version.
Fix this by using the actual FW version stored in the FW file
header record.
Signed-off-by: Lior David <qca_liord@qca.qualcomm.com>
Signed-off-by: Maya Erez <qca_merez@qca.qualcomm.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>

When driver is loaded, extract a capabilities record
from the FW file. This record contains bits indicating
which optional features are supported by this FW.
The driver can use this information to determine
which functionality to support and/or expose to user
space.
The extraction is done before wiphy structure is
registered, because the capabilities can affect
information published by the this structure.
Signed-off-by: Lior David <qca_liord@qca.qualcomm.com>
Signed-off-by: Maya Erez <qca_merez@qca.qualcomm.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>

Align to latest version of the auto generated wmi file
describing the interface with FW.
Signed-off-by: Lior David <qca_liord@qca.qualcomm.com>
Signed-off-by: Maya Erez <qca_merez@qca.qualcomm.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>

Currently the places that check wil->scan_request and
call cfg80211_scan_done are not consistently protected,
so there is a risk that cfg80211_scan_done will be called
with NULL scan_request, causing a kernel crash.
Fix this by using p2p_wdev_mutex in few other places
that access scan_request. This makes sense since
scan_request may point to p2p_wdev, and it is not worth
the extra complexity of adding a new mutex.
Signed-off-by: Lior David <qca_liord@qca.qualcomm.com>
Signed-off-by: Maya Erez <qca_merez@qca.qualcomm.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>

HW Rx filters and masks are not configured
properly by firmware during boot sequences. The
MAC_PCU_ADDR1 is set to 0s instead of 1s which
allows the HW to ACK any frame that passes through
MAC_PCU_RX_FILTER. The MAC_PCU_RX_FILTER itself
is misconfigured on boot as well.

The combination of these bugs ended up with the
following manifestations:
 - "no channel configured; ignoring frame(s)!"
   warnings in the driver
 - spurious ACKs (transmission) on the air during
   firmware bootup sequences

The former was a long standing and known bug
originally though mostly harmless.

However Marek recently discovered that this
problem also involves ACKing *all* frames the HW
receives (including beacons ;). Such frames
are delivered to host and generate the former
warning as well.

This could be a problem with regulatory compliance
in some rare cases (e.g. Taiwan which forbids
transmissions on channel 36 which is the default
bootup channel on 5Ghz band cards). The good news
is that it'd require someone else to violate
regulatory first to coerce our device to generate
and transmit an ACK.

The problem could be reproduced in a rather busy
environment that has a lot of APs. The likelihood
could be increased by injecting an msleep() of
5000 or longer immediately after
ath10k_htt_setup() in ath10k_core_start().

The reason why the former warnings were only
showing up seldom is because the device was either
quickly reset again (i.e. during firmware probing)
or wmi vdev was created (which fixes hw and fw
states).

It is technically possible for host driver to
override adequate hw registers however this can't
work reliably because the bug root cause lies in
incorrect firmware state on boot (internal
structure used to program MAC_PCU_ADDR1 is not
properly initialized) and only vdev create/delete
events can fix it. This is why the patch takes
dummy vdev approach.

This could be fixed in firmware as well but having
this fixed in driver is more robust, most notably
when thinking of users of older firmware such as
999.999.0.636.
Reported-by: Marek Puzyniak <marek.puzyniak@tieto.com>
Signed-off-by: Michal Kazior <michal.kazior@tieto.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>

This allows placing command barriers for explicit
serializing and synchronizing state.

Useful for future driver development.
Signed-off-by: Michal Kazior <michal.kazior@tieto.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>

Will be useful for implementing command barriers.
Signed-off-by: Michal Kazior <michal.kazior@tieto.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>

Will be useful for implementing command barriers.
Signed-off-by: Michal Kazior <michal.kazior@tieto.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>

This patch adds testmode support for 10.4 based chipsets
and added code swap support for UTF binary.
Signed-off-by: Tamizh chelvam <c_traja@qti.qualcomm.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>

Currently testmode events for 10.x firmware are processed from
10.1 wmi event processing. This patch is used to handle testmode
events in 10.2 and 10.4 based firmware.
Signed-off-by: Tamizh chelvam <c_traja@qti.qualcomm.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>

Preparation to make use of firmware_swap_code_seg_info for UTF binary.
Signed-off-by: Tamizh chelvam <c_traja@qti.qualcomm.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>

Currently wiphy structure is initialized and registered
in wil_if_alloc, before some information is available such
as MAC address and capabilities. As a result there is a
small chance user space will get incorrect information
from calls such as NL80211_CMD_GET_WIPHY.
Fix this by seperating the registration and moving it
to wil_if_add which is executed later, after all
relevant information is known.
Signed-off-by: Lior David <qca_liord@qca.qualcomm.com>
Signed-off-by: Maya Erez <qca_merez@qca.qualcomm.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>

txdata->enabled is used in order to determine if the TX vring
is valid. As the data transmit is handled in a different context,
in case txdata->enabled is set before vring->hwtail is updated,
an old or corrupted vring->hwtail can be used.
Protect setting of txdata->enabled and vring->hwtail to prevent a
case where TX vring start handling TX packets before setting
vring->hwtail.
Signed-off-by: Maya Erez <qca_merez@qca.qualcomm.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>

Stations disconnection is executed as part of wil_reset so no
need to do it in wil_down.
Removal of the disconnect operation will also preserve the lock
of wil->mutex during the whole reset flow and prevent handling of
connect event while resetting.
Set wil_status_resetting in earlier stage in the flow to prevent
double resetting call in case communication with FW fails while
bringing the interface down.
Signed-off-by: Lazar Alexei <qca_ailizaro@qca.qualcomm.com>
Signed-off-by: Maya Erez <qca_merez@qca.qualcomm.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>

fix stop p2p device handling to identify between search
and listen and update the upper layers with the appropriate
notification.
The stop of p2p radio operations also needs to be performed
in __wil_down.
Signed-off-by: Maya Erez <qca_merez@qca.qualcomm.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>

Change the logging category of HALP functions from
MISC to IRQ, since the HALP mechanism is closely
related to interrupts. Both HALP and IRQ create
a heavy load of logging messages when enabled,
so their logging is typically disabled during normal debug
scenarios. Having them in the same logging category
will make it easier to disable logging for both in one go.
Signed-off-by: Lior David <qca_liord@qca.qualcomm.com>
Signed-off-by: Maya Erez <qca_merez@qca.qualcomm.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>

According to the spec the PN should be calculated per TID.
In the current implementation, the PN and key_set were set
only for TID 0, therefore only traffic for TID 0 was supported.
In order to support all TIDs, the key_set and PN should be set
for all the TIDs.
Signed-off-by: Maya Erez <qca_merez@qca.qualcomm.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>

In case HALP vote times out, we need to mask the HALP IRQ, as done
in case the interrupt is received, as this interrupt should be
set until completion of the low latency operation.
Signed-off-by: Maya Erez <qca_merez@qca.qualcomm.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>

Align to latest version of the auto generated wmi file
describing the interface with FW.
Signed-off-by: Maya Erez <qca_merez@qca.qualcomm.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>

just to comply with current ath9k_hw_nvram_read to return value, hence
behaving reacting accordingly.
Signed-off-by: Eduardo Abinader <eduardo.abinader@riverbed.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>

Fixes smatch warning:

ath9k_vif_iter_set_beacon() warn if statement not indented
Signed-off-by: Bob Copeland <me@bobcopeland.com>
Reviewed-by: Julian Calaby <julian.calaby@gmail.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>

Minor overlapping changes for both merge conflicts.

Resolution work done by Stephen Rothwell was used
as a reference.
Signed-off-by: David S. Miller <davem@davemloft.net>

Pull networking fixes from David Miller:

 1) Buffers powersave frame test is reversed in cfg80211, fix from Felix
    Fietkau.

 2) Remove bogus WARN_ON in openvswitch, from Jarno Rajahalme.

 3) Fix some tg3 ethtool logic bugs, and one that would cause no
    interrupts to be generated when rx-coalescing is set to 0.  From
    Satish Baddipadige and Siva Reddy Kallam.

 4) QLCNIC mailbox corruption and napi budget handling fix from Manish
    Chopra.

 5) Fix fib_trie logic when walking the trie during /proc/net/route
    output than can access a stale node pointer.  From David Forster.

 6) Several sctp_diag fixes from Phil Sutter.

 7) PAUSE frame handling fixes in mlxsw driver from Ido Schimmel.

 8) Checksum fixup fixes in bpf from Daniel Borkmann.

 9) Memork leaks in nfnetlink, from Liping Zhang.

10) Use after free in rxrpc, from David Howells.

11) Use after free in new skb_array code of macvtap driver, from Jason
    Wang.

12) Calipso resource leak, from Colin Ian King.

13) mediatek bug fixes (missing stats sync init, etc.) from Sean Wang.

14) Fix bpf non-linear packet write helpers, from Daniel Borkmann.

15) Fix lockdep splats in macsec, from Sabrina Dubroca.

16) hv_netvsc bug fixes from Vitaly Kuznetsov, mostly to do with VF
    handling.

17) Various tc-action bug fixes, from CONG Wang.

* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net: (116 commits)
  net_sched: allow flushing tc police actions
  net_sched: unify the init logic for act_police
  net_sched: convert tcf_exts from list to pointer array
  net_sched: move tc offload macros to pkt_cls.h
  net_sched: fix a typo in tc_for_each_action()
  net_sched: remove an unnecessary list_del()
  net_sched: remove the leftover cleanup_a()
  mlxsw: spectrum: Allow packets to be trapped from any PG
  mlxsw: spectrum: Unmap 802.1Q FID before destroying it
  mlxsw: spectrum: Add missing rollbacks in error path
  mlxsw: reg: Fix missing op field fill-up
  mlxsw: spectrum: Trap loop-backed packets
  mlxsw: spectrum: Add missing packet traps
  mlxsw: spectrum: Mark port as active before registering it
  mlxsw: spectrum: Create PVID vPort before registering netdevice
  mlxsw: spectrum: Remove redundant errors from the code
  mlxsw: spectrum: Don't return upon error in removal path
  i40e: check for and deal with non-contiguous TCs
  ixgbe: Re-enable ability to toggle VLAN filtering
  ixgbe: Force VLNCTRL.VFE to be set in all VMDq paths
  ...

Tom Herbert says:

====================
strp: Stream parser for messages

This patch set introduces a utility for parsing application layer
protocol messages in a TCP stream. This is a generalization of the
mechanism implemented of Kernel Connection Multiplexor.

This patch set adapts KCM to use the strparser. We expect that kTLS
can use this mechanism also. RDS would probably be another candidate
to use a common stream parsing mechanism.

The API includes a context structure, a set of callbacks, utility
functions, and a data ready function. The callbacks include
a parse_msg function that is called to perform parsing (e.g.
BPF parsing in case of KCM), and a rcv_msg function that is called
when a full message has been completed.

For strparser we specify the return codes from the parser to allow
the backend to indicate that control of the socket should be
transferred back to userspace to handle some exceptions in the
stream: The return values are:

      >0 : indicates length of successfully parsed message
       0  : indicates more data must be received to parse the message
       -ESTRPIPE : current message should not be processed by the
          kernel, return control of the socket to userspace which
          can proceed to read the messages itself
       other < 0 : Error is parsing, give control back to userspace
          assuming that synchronization is lost and the stream
          is unrecoverable (application expected to close TCP socket)

There is one issue I haven't been able to fully resolve. If parse_msg
returns ESTRPIPE (wants control back to userspace) the parser may
already have consumed some bytes of the message. There is no way to
put bytes back into the TCP receive queue and tcp_read_sock does not
allow an easy way to peek messages. In lieu of a better solution, we
return ENODATA on the socket to indicate that the data stream is
unrecoverable (application needs to close socket). This condition
should only happen if an application layer message header is split
across two skbuffs and parsing just the first skbuff wasn't sufficient
to determine the that transfer to userspace is needed.

This patch set contains:

  - strparser implementation
  - changes to kcm to use strparser
  - strparser.txt documentation

v2:
  - Add copyright notice to C files
  - Remove GPL module license from strparser.c
  - Add report of rxpause

v3:
  - Restore GPL module license
  - Use EXPORT_SYMBOL_GPL

v4:
  - Removed unused function, changed another to be static as suggested
    by davem
  - Rewoked data_ready to be called from upper layer, no longer requires
    taking over socket data_ready callback as suggested by Lance Chao

Tested:
  - Ran a KCM thrash test for 24 hours. No behavioral or performance
    differences observed.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

Signed-off-by: Tom Herbert <tom@herbertland.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Adapt KCM to use the stream parser. This mostly involves removing
the RX handling and setting up the strparser using the interface.
Signed-off-by: Tom Herbert <tom@herbertland.com>
Signed-off-by: David S. Miller <davem@davemloft.net>