In preparation to enable -Wimplicit-fallthrough for Clang, fix a warning
by explicitly adding a break statement instead of letting the code fall
through to the next case.

Link: https://github.com/KSPP/linux/issues/115Signed-off-by: NGustavo A. R. Silva <gustavoars@kernel.org>
Signed-off-by: NKalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/b0d4c50b803bc38ed370521b9b0a44365cae9386.1605896060.git.gustavoars@kernel.org

In preparation to enable -Wimplicit-fallthrough for Clang, fix a warning
by explicitly adding a break statement instead of letting the code fall
through to the next case.

Link: https://github.com/KSPP/linux/issues/115Signed-off-by: NGustavo A. R. Silva <gustavoars@kernel.org>
Signed-off-by: NKalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/b3c0f74f5b6e6bff9f1609b310319b6fdd9ee205.1605896059.git.gustavoars@kernel.org

mt76 patches for 5.11

* mt7915 fixes
* mt7615 fixes
* support for more sta interfaces on mt7615/mt7915
* mt7915 encap offload
* performance improvements
* channel noise report on mt7915
* usb/sdio support improvements
* mt7915 testmode support
* mt7915 DBDC support
* warning fixes

When 8822CE is associating with AP, driver will poll status bit of
IQ calibration to confirm the IQ calibration is done, and then move on
the association process. Current polling time for IQ calibration is 6
seconds.

But occasionally driver fails in polling the status bit because the status
bit is not set after IQ calibration is done. When it happends, association
process will be serieously delayed up to 6 seconds. To avoid it, we reduce
polling time to 300ms, in which the IQ calibration can be done.
Signed-off-by: NChin-Yen Lee <timlee@realtek.com>
Signed-off-by: NPing-Ke Shih <pkshih@realtek.com>
Signed-off-by: NKalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20201208014503.12118-1-pkshih@realtek.com

'const struct dev_pm_ops rtw_pm_ops' is declared by pci.c, and it should be
declare as 'extern' in pci.h. Without 'extern' causes every file including
pci.h has an individual instance of rtw_pm_ops but not reference to the one
declared in pci.c

If kernel config, like test robot, doesn't build driver as module, it leads
multiple definition.
Reported-by: Nkernel test robot <lkp@intel.com>
Fixes: 2e86ef41 ("rtw88: pci: Add prototypes for .probe, .remove and .shutdown")
Signed-off-by: NPing-Ke Shih <pkshih@realtek.com>
Signed-off-by: NKalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20201208013746.11065-1-pkshih@realtek.com

mwifiex_cmd_802_11_ad_hoc_start() calls memcpy() without checking
the destination size may trigger a buffer overflower,
which a local user could use to cause denial of service
or the execution of arbitrary code.
Fix it by putting the length check before calling memcpy().
Signed-off-by: NZhang Xiaohui <ruc_zhangxiaohui@163.com>
Signed-off-by: NKalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20201206084801.26479-1-ruc_zhangxiaohui@163.com

The pointer 'entry' is being initialized with a value that is never read
and it is being updated later with a new value.  The initialization is
redundant and can be removed.

Addresses-Coverity: ("Unused value")
Signed-off-by: NColin Ian King <colin.king@canonical.com>
Signed-off-by: NKalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20201204180459.1148257-1-colin.king@canonical.com

Fix to return a negative error code from the error handling
case instead of 0, as done elsewhere in this function.

Fixes: cc0b88cf ("[PATCH] Add adm8211 802.11b wireless driver")
Reported-by: NHulk Robot <hulkci@huawei.com>
Signed-off-by: NZhang Changzhong <zhangchangzhong@huawei.com>
Signed-off-by: NKalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/1607071638-33619-1-git-send-email-zhangchangzhong@huawei.com

When driver was developed, FCC regulation didn't enable channel 144
and there was no demand for channel 144 at that time. Although HW
actually supports channel 144, driver didn't announce channel 144.
Therefore, channel 144 (20 MHz), channel 142 (40 MHz) and channel
138 (80 MHz) couldn't be used.

Today, channel 144 has been enabled by regulations and
is gradually being supported. With test requirements,
we declare hw supports channel 144.
Signed-off-by: NZong-Zhe Yang <kevin_yang@realtek.com>
Signed-off-by: NPing-Ke Shih <pkshih@realtek.com>
Signed-off-by: NKalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20201204013823.3729-1-pkshih@realtek.com

Currently the variable 'interval' is not initialized and is only set
to 1 when oex_stat->bt_418_hid_existi is true.  Fix this by inintializing
variable interval to 0 (which I'm assuming is the intended default).

Addresses-Coverity: ("Uninitalized scalar variable")
Fixes: 5b2e9a35 ("rtw88: coex: add feature to enhance HID coexistence performance")
Signed-off-by: NColin Ian King <colin.king@canonical.com>
Acked-by: NPing-Ke Shih <pkshih@realtek.com>
Signed-off-by: NKalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20201203175142.1071738-1-colin.king@canonical.com

The assignment to pointer vif is redundant as the assigned value
is never read, hence it can be removed.

Addresses-Coverity: ("Unused value")
Signed-off-by: NColin Ian King <colin.king@canonical.com>
Acked-by: NAjay Singh <ajay.kathat@microchip.com>
Signed-off-by: NKalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20201203174316.1071446-1-colin.king@canonical.com

As of 6-DEC-2019, NXP has acquired Marvell’s Wireless business
unit. This change is to update the license text accordingly.

commit 932183aa ("mwifiex: change license text from MARVELL
to NXP") does this, but it left out two files.
Signed-off-by: NJames Cao <zheng.cao@nxp.com>
Signed-off-by: NCathy Luo <xiaohua.luo@nxp.com>
Signed-off-by: NGanapathi Bhat <ganapathi.bhat@nxp.com>
Signed-off-by: NKalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/1606814307-32715-1-git-send-email-ganapathi.bhat@nxp.com

he wrappers in include/linux/pci-dma-compat.h should go away.

The patch has been generated with the coccinelle script below and has been
hand modified to replace GFP_ with a correct flag.
It has been compile tested.

When memory is allocated in 'mwl8k_rxq_init()' and 'mwl8k_txq_init()'
GFP_KERNEL can be used because this flag is already used in a 'kcalloc()'
call, just a few line below.

When memory is allocated in 'mwl8k_firmware_load_success()' GFP_KERNEL can
be used because this flag is already used within 'ieee80211_register_hw()'
which is called just a few line below.

@@
@@
-    PCI_DMA_BIDIRECTIONAL
+    DMA_BIDIRECTIONAL

@@
@@
-    PCI_DMA_TODEVICE
+    DMA_TO_DEVICE

@@
@@
-    PCI_DMA_FROMDEVICE
+    DMA_FROM_DEVICE

@@
@@
-    PCI_DMA_NONE
+    DMA_NONE

@@
expression e1, e2, e3;
@@
-    pci_alloc_consistent(e1, e2, e3)
+    dma_alloc_coherent(&e1->dev, e2, e3, GFP_)

@@
expression e1, e2, e3;
@@
-    pci_zalloc_consistent(e1, e2, e3)
+    dma_alloc_coherent(&e1->dev, e2, e3, GFP_)

@@
expression e1, e2, e3, e4;
@@
-    pci_free_consistent(e1, e2, e3, e4)
+    dma_free_coherent(&e1->dev, e2, e3, e4)

@@
expression e1, e2, e3, e4;
@@
-    pci_map_single(e1, e2, e3, e4)
+    dma_map_single(&e1->dev, e2, e3, e4)

@@
expression e1, e2, e3, e4;
@@
-    pci_unmap_single(e1, e2, e3, e4)
+    dma_unmap_single(&e1->dev, e2, e3, e4)

@@
expression e1, e2, e3, e4, e5;
@@
-    pci_map_page(e1, e2, e3, e4, e5)
+    dma_map_page(&e1->dev, e2, e3, e4, e5)

@@
expression e1, e2, e3, e4;
@@
-    pci_unmap_page(e1, e2, e3, e4)
+    dma_unmap_page(&e1->dev, e2, e3, e4)

@@
expression e1, e2, e3, e4;
@@
-    pci_map_sg(e1, e2, e3, e4)
+    dma_map_sg(&e1->dev, e2, e3, e4)

@@
expression e1, e2, e3, e4;
@@
-    pci_unmap_sg(e1, e2, e3, e4)
+    dma_unmap_sg(&e1->dev, e2, e3, e4)

@@
expression e1, e2, e3, e4;
@@
-    pci_dma_sync_single_for_cpu(e1, e2, e3, e4)
+    dma_sync_single_for_cpu(&e1->dev, e2, e3, e4)

@@
expression e1, e2, e3, e4;
@@
-    pci_dma_sync_single_for_device(e1, e2, e3, e4)
+    dma_sync_single_for_device(&e1->dev, e2, e3, e4)

@@
expression e1, e2, e3, e4;
@@
-    pci_dma_sync_sg_for_cpu(e1, e2, e3, e4)
+    dma_sync_sg_for_cpu(&e1->dev, e2, e3, e4)

@@
expression e1, e2, e3, e4;
@@
-    pci_dma_sync_sg_for_device(e1, e2, e3, e4)
+    dma_sync_sg_for_device(&e1->dev, e2, e3, e4)

@@
expression e1, e2;
@@
-    pci_dma_mapping_error(e1, e2)
+    dma_mapping_error(&e1->dev, e2)

@@
expression e1, e2;
@@
-    pci_set_dma_mask(e1, e2)
+    dma_set_mask(&e1->dev, e2)

@@
expression e1, e2;
@@
-    pci_set_consistent_dma_mask(e1, e2)
+    dma_set_coherent_mask(&e1->dev, e2)
Signed-off-by: NChristophe JAILLET <christophe.jaillet@wanadoo.fr>
Signed-off-by: NKalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20201129150844.1466214-1-christophe.jaillet@wanadoo.fr

Also strip out other duplicates from driver specific headers.

Ensure 'main.h' is explicitly included in 'pci.h' since the latter
uses some defines from the former.  It avoids issues like:

 from drivers/net/wireless/realtek/rtw88/rtw8822be.c:5:
 drivers/net/wireless/realtek/rtw88/pci.h:209:28: error: ‘RTK_MAX_TX_QUEUE_NUM’ undeclared here (not in a function); did you mean ‘RTK_MAX_RX_DESC_NUM’?
 209 | DECLARE_BITMAP(tx_queued, RTK_MAX_TX_QUEUE_NUM);
 | ^~~~~~~~~~~~~~~~~~~~

Fixes the following W=1 kernel build warning(s):

 drivers/net/wireless/realtek/rtw88/pci.c:1488:5: warning: no previous prototype for ‘rtw_pci_probe’ [-Wmissing-prototypes]
 1488 | int rtw_pci_probe(struct pci_dev *pdev,
 | ^~~~~~~~~~~~~
 drivers/net/wireless/realtek/rtw88/pci.c:1568:6: warning: no previous prototype for ‘rtw_pci_remove’ [-Wmissing-prototypes]
 1568 | void rtw_pci_remove(struct pci_dev *pdev)
 | ^~~~~~~~~~~~~~
 drivers/net/wireless/realtek/rtw88/pci.c:1590:6: warning: no previous prototype for ‘rtw_pci_shutdown’ [-Wmissing-prototypes]
 1590 | void rtw_pci_shutdown(struct pci_dev *pdev)
 | ^~~~~~~~~~~~~~~~

Cc: Yan-Hsuan Chuang <yhchuang@realtek.com>
Cc: Kalle Valo <kvalo@codeaurora.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: linux-wireless@vger.kernel.org
Cc: netdev@vger.kernel.org
Signed-off-by: NLee Jones <lee.jones@linaro.org>
Signed-off-by: NKalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20201126133152.3211309-18-lee.jones@linaro.org

Ido Schimmel says:

====================
mlxsw: Misc updates

This patchset contains miscellaneous patches we gathered in our queue.
Some of them are dependencies of larger patchsets that I will submit
later this cycle.

Patches #1-#3 perform small non-functional changes in mlxsw.

Patch #4 adds more extended ack messages in mlxsw.

Patch #5 adds devlink parameters documentation for mlxsw. To be extended
with more parameters this cycle.

Patches #6-#7 perform small changes in forwarding selftests
infrastructure.
====================
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Turned out that mlxsw_sp_ipip_fib_entry_op_gre4() does not need to
figure out the IP address and virtual router id. Those are exactly
the same as in the fib_entry it is called for. So just use that and
reduce mlxsw_sp_ipip_fib_entry_op_gre4() function to only call
mlxsw_sp_ipip_fib_entry_op_gre4_rtdp() make the ipip decap op
code similar to nve.
Signed-off-by: NJiri Pirko <jiri@nvidia.com>
Reviewed-by: NPetr Machata <petrm@nvidia.com>
Signed-off-by: NIdo Schimmel <idosch@nvidia.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The indicated version fixes an issue whereby the MOMTE register would by
default enable mirroring of ECN-marked traffic from all traffic classes,
once the ECN mirroring was configured. This fix is necessary for offload
of RED "ecn_mark" qevent.
Signed-off-by: NPetr Machata <petrm@nvidia.com>
Signed-off-by: NIdo Schimmel <idosch@nvidia.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Suppresses the following coccinelle warning:

drivers/net/ethernet/mellanox/mlxsw/core_acl_flex_keys.c:139:3-7:
WARNING use flexible-array member instead
Signed-off-by: NIdo Schimmel <idosch@nvidia.com>
Reviewed-by: NJiri Pirko <jiri@nvidia.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Suppresses the following coccinelle warning:

drivers/net/ethernet/mellanox/mlxsw/spectrum_mr.c:18:15-19: WARNING use flexible-array member instead
Signed-off-by: NIdo Schimmel <idosch@nvidia.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Currently, mlxsw triggers the 'devlink:devlink_hwmsg' tracepoint
whenever a request is sent to the device and whenever a response is
received from it. However, the tracepoint is not triggered when an event
(e.g., port up / down) is received from the device.

Also trace EMAD events in order to log a more complete picture of all
the exchanged hardware messages.
Signed-off-by: NIdo Schimmel <idosch@nvidia.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Test that the reference count of a router interface (RIF) configured for
a LAG is incremented / decremented when ports join / leave the LAG. Use
the offload indication on routes configured on the RIF to understand if
it was created / destroyed.

The test fails without the previous patch.
Signed-off-by: NIdo Schimmel <idosch@nvidia.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

In case a router interface (RIF) is configured for a LAG, make sure its
configuration is applied on the new LAG member.
Signed-off-by: NIdo Schimmel <idosch@nvidia.com>
Reviewed-by: NJiri Pirko <jiri@nvidia.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Heiner Kallweit says:

====================
r8169: improve rtl_rx and NUM_RX_DESC handling

This series improves rtl_rx() and the handling of NUM_RX_DESC.
====================
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

After recent changes there's no need any longer to define NUM_RX_DESC
as an unsigned value.
Signed-off-by: NHeiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

There's no need to check min(budget, NUM_RX_DESC). At first budget
(NAPI_POLL_WEIGHT = 64) is less then NUM_RX_DESC (256).
And more important: Even in case of budget > NUM_RX_DESC we could
safely continue processing descriptors as long as they are owned by
the CPU. In addition replace rx_left with a normal counter variable,
this allows to simplify the code. Last but not least there's no need
any longer to pass the budget as an u32.
Signed-off-by: NHeiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

There is a spelling mistake in the Kconfig help text. Fix it.
Signed-off-by: NColin Ian King <colin.king@canonical.com>
Link: https://lore.kernel.org/r/20201204194549.1153063-1-colin.king@canonical.comSigned-off-by: NJakub Kicinski <kuba@kernel.org>

Simon Wunderlich says:

====================
This cleanup patchset includes the following patches:

 - bump version strings, by Simon Wunderlich

 - update include for min/max helpers, by Sven Eckelmann

 - add infrastructure and netlink functions for routing algo selection,
   by Sven Eckelmann (2 patches)

 - drop deprecated debugfs and sysfs support and obsoleted
   functionality, by Sven Eckelmann (3 patches)

 - drop unused include in fragmentation.c, by Simon Wunderlich

* tag 'batadv-next-pullrequest-20201204' of git://git.open-mesh.org/linux-merge:
  batman-adv: Drop unused soft-interface.h include in fragmentation.c
  batman-adv: Drop legacy code for auto deleting mesh interfaces
  batman-adv: Drop deprecated debugfs support
  batman-adv: Drop deprecated sysfs support
  batman-adv: Allow selection of routing algorithm over rtnetlink
  batman-adv: Prepare infrastructure for newlink settings
  batman-adv: Add new include for min/max helpers
  batman-adv: Start new development cycle
====================

Link: https://lore.kernel.org/r/20201204154631.21063-1-sw@simonwunderlich.deSigned-off-by: NJakub Kicinski <kuba@kernel.org>

When CONFIG_OF is disabled, there is a harmless warning about
an unused variable:

enetc_pf.c: In function 'enetc_phylink_create':
enetc_pf.c:981:17: error: unused variable 'dev' [-Werror=unused-variable]

Slightly rearrange the code to pass around the of_node as a
function argument, which avoids the problem without hurting
readability.

Fixes: 71b77a7a ("enetc: Migrate to PHYLINK and PCS_LYNX")
Signed-off-by: NArnd Bergmann <arnd@arndb.de>
Signed-off-by: NClaudiu Manoil <claudiu.manoil@nxp.com>
Link: https://lore.kernel.org/r/20201204120800.17193-1-claudiu.manoil@nxp.comSigned-off-by: NJakub Kicinski <kuba@kernel.org>

The OpenCompute time card is an atomic clock along with
a GPS receiver that provides a Grandmaster clock source
for a PTP enabled network.

More information is available at http://www.timingcard.com/Signed-off-by: NJonathan Lemon <jonathan.lemon@gmail.com>
Acked-by: NRichard Cochran <richardcochran@gmail.com>
Link: https://lore.kernel.org/r/20201204035128.2219252-2-jonathan.lemon@gmail.comSigned-off-by: NJakub Kicinski <kuba@kernel.org>

implement the NCI 2.x initial sequence to support NCI 2.x NFCC.
Since NCI 2.0, CORE_RESET and CORE_INIT sequence have been changed.
If NFCEE supports NCI 2.x, then NCI 2.x initial sequence will work.

In NCI 1.0, Initial sequence and payloads are as below:
(DH)                     (NFCC)
 |  -- CORE_RESET_CMD --> |
 |  <-- CORE_RESET_RSP -- |
 |  -- CORE_INIT_CMD -->  |
 |  <-- CORE_INIT_RSP --  |
 CORE_RESET_RSP payloads are Status, NCI version, Configuration Status.
 CORE_INIT_CMD payloads are empty.
 CORE_INIT_RSP payloads are Status, NFCC Features,
    Number of Supported RF Interfaces, Supported RF Interface,
    Max Logical Connections, Max Routing table Size,
    Max Control Packet Payload Size, Max Size for Large Parameters,
    Manufacturer ID, Manufacturer Specific Information.

In NCI 2.0, Initial Sequence and Parameters are as below:
(DH)                     (NFCC)
 |  -- CORE_RESET_CMD --> |
 |  <-- CORE_RESET_RSP -- |
 |  <-- CORE_RESET_NTF -- |
 |  -- CORE_INIT_CMD -->  |
 |  <-- CORE_INIT_RSP --  |
 CORE_RESET_RSP payloads are Status.
 CORE_RESET_NTF payloads are Reset Trigger,
    Configuration Status, NCI Version, Manufacturer ID,
    Manufacturer Specific Information Length,
    Manufacturer Specific Information.
 CORE_INIT_CMD payloads are Feature1, Feature2.
 CORE_INIT_RSP payloads are Status, NFCC Features,
    Max Logical Connections, Max Routing Table Size,
    Max Control Packet Payload Size,
    Max Data Packet Payload Size of the Static HCI Connection,
    Number of Credits of the Static HCI Connection,
    Max NFC-V RF Frame Size, Number of Supported RF Interfaces,
    Supported RF Interfaces.
Signed-off-by: NBongsu Jeon <bongsu.jeon@samsung.com>
Link: https://lore.kernel.org/r/20201202223147.3472-1-bongsu.jeon@samsung.comSigned-off-by: NJakub Kicinski <kuba@kernel.org>

Connect hosts H1 and H2 using two intermediate encapsulation routers
(LER1 and LER2). These routers encapsulate traffic from the hosts,
including the original Ethernet header, into MPLS.

Use ping to test reachability between H1 and H2.
Signed-off-by: NGuillaume Nault <gnault@redhat.com>
Link: https://lore.kernel.org/r/625f5c1aafa3a8085f8d3e082d680a82e16ffbaa.1606918980.git.gnault@redhat.comSigned-off-by: NJakub Kicinski <kuba@kernel.org>

The macro use will already have a semicolon.
Clean up escaped newlines.
Signed-off-by: NTom Rix <trix@redhat.com>
Link: https://lore.kernel.org/r/20201202163622.3733506-1-trix@redhat.comSigned-off-by: NJakub Kicinski <kuba@kernel.org>

We add the support to remove a specific node down with 128bit
node identifier, as an alternative to legacy 32-bit node address.

example:
$tipc peer remove identiy <1001002|16777777>
Acked-by: NJon Maloy <jmaloy@redhat.com>
Signed-off-by: NHoang Le <hoang.h.le@dektech.com.au>
Link: https://lore.kernel.org/r/20201203035045.4564-1-hoang.h.le@dektech.com.auSigned-off-by: NJakub Kicinski <kuba@kernel.org>

There is a regular need in the kernel to provide a way to declare having a
dynamically sized set of trailing elements in a structure. Kernel code
should always use "flexible array members"[1] for these cases. The older
style of one-element or zero-length arrays should no longer be used[2].

[1] https://en.wikipedia.org/wiki/Flexible_array_member
[2] https://www.kernel.org/doc/html/v5.9/process/deprecated.html#zero-length-and-one-element-arrays

Cc: Gustavo A. R. Silva <gustavoars@kernel.org>
Signed-off-by: NSimon Horman <simon.horman@netronome.com>
Signed-off-by: NLouis Peens <louis.peens@netronome.com>
Link: https://lore.kernel.org/r/20201204125601.24876-1-simon.horman@netronome.comSigned-off-by: NJakub Kicinski <kuba@kernel.org>

If there isn't a proper NFC firmware image, Bootloader mode will be
skipped.
Signed-off-by: NBongsu Jeon <bongsu.jeon@samsung.com>
Reviewed-by: NKrzysztof Kozlowski <krzk@kernel.org>
Link: https://lore.kernel.org/r/20201203225257.2446-1-bongsu.jeon@samsung.comSigned-off-by: NJakub Kicinski <kuba@kernel.org>

Arjun Roy says:

====================
Perf. optimizations for TCP Recv. Zerocopy

This patchset contains several optimizations for TCP Recv. Zerocopy.

Summarized:
1. It is possible that a read payload is not exactly page aligned -
that there may exist "straggler" bytes that we cannot map into the
caller's address space cleanly. For this, we allow the caller to
provide as argument a "hybrid copy buffer", turning
getsockopt(TCP_ZEROCOPY_RECEIVE) into a "hybrid" operation that allows
the caller to avoid a subsequent recvmsg() call to read the
stragglers.

2. Similarly, for "small" read payloads that are either below the size
of a page, or small enough that remapping pages is not a performance
win - we allow the user to short-circuit the remapping operations
entirely and simply copy into the buffer provided.

Some of the patches in the middle of this set are refactors to support
this "short-circuiting" optimization.

3. We allow the user to provide a hint that performing a page zap
operation (and the accompanying TLB shootdown) may not be necessary,
for the provided region that the kernel will attempt to map pages
into. This allows us to avoid this expensive operation while holding
the socket lock, which provides a significant performance advantage.

With all of these changes combined, "medium" sized receive traffic
(multiple tens to few hundreds of KB) see significant efficiency gains
when using TCP receive zerocopy instead of regular recvmsg(). For
example, with RPC-style traffic with 32KB messages, there is a roughly
15% efficiency improvement when using zerocopy. Without these changes,
there is a roughly 60-70% efficiency reduction with such messages when
employing zerocopy.
====================

Link: https://lore.kernel.org/r/20201202225349.935284-1-arjunroy.kdev@gmail.comSigned-off-by: NJakub Kicinski <kuba@kernel.org>

Zapping pages is required only if we are calling vm_insert_page into a
region where pages had previously been mapped. Receive zerocopy allows
reusing such regions, and hitherto called zap_page_range() before
calling vm_insert_page() in that range.

zap_page_range() can also be triggered from userspace with
madvise(MADV_DONTNEED). If userspace is configured to call this before
reusing a segment, or if there was nothing mapped at this virtual
address to begin with, we can avoid calling zap_page_range() under the
socket lock. That said, if userspace does not do that, then we are
still responsible for calling zap_page_range().

This patch adds a flag that the user can use to hint to the kernel
that a zap is not required. If the flag is not set, or if an older
user application does not have a flags field at all, then the kernel
calls zap_page_range as before. Also, if the flag is set but a zap is
still required, the kernel performs that zap as necessary. Thus
incorrectly indicating that a zap can be avoided does not change the
correctness of operation. It also increases the batchsize for
vm_insert_pages and prefetches the page struct for the batch since
we're about to bump the refcount.

An alternative mechanism could be to not have a flag, assume by
default a zap is not needed, and fall back to zapping if needed.
However, this would harm performance for older applications for which
a zap is necessary, and thus we implement it with an explicit flag
so newer applications can opt in.

When using RPC-style traffic with medium sized (tens of KB) RPCs, this
change yields an efficency improvement of about 30% for QPS/CPU usage.
Signed-off-by: NArjun Roy <arjunroy@google.com>
Signed-off-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NSoheil Hassas Yeganeh <soheil@google.com>
Signed-off-by: NJakub Kicinski <kuba@kernel.org>

Set zerocopy hint, event when falling back to copy, so that the
pending data can be efficiently received using zerocopy when
possible.
Signed-off-by: NArjun Roy <arjunroy@google.com>
Signed-off-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NSoheil Hassas Yeganeh <soheil@google.com>
Signed-off-by: NJakub Kicinski <kuba@kernel.org>

Sometimes, we may call tcp receive zerocopy when inq is 0,
or inq < PAGE_SIZE, or inq is generally small enough that
it is cheaper to copy rather than remap pages.

In these cases, we may want to either return early (inq=0) or
attempt to use the provided copy buffer to simply copy
the received data.

This allows us to save both system call overhead and
the latency of acquiring mmap_sem in read mode for cases where
it would be useless to do so.

This patchset enables this behaviour by:
1. Returning quickly if inq is 0.
2. Attempting to perform a regular copy if a hybrid copybuffer is
   provided and it is large enough to absorb all available bytes.
3. Return quickly if no such buffer was provided and there are less
   than PAGE_SIZE bytes available.

For small RPC ping-pong workloads, normally we would have
1 getsockopt(), 1 recvmsg() and 1 sendmsg() call per RPC. With this
change, we remove the recvmsg() call entirely, reducing the syscall
overhead by about 33%. In testing with small (hundreds of bytes)
RPC traffic, this yields a syscall reduction of about 33% and
an efficiency gain of about 3-5% when defined as QPS/CPU Util.
Signed-off-by: NArjun Roy <arjunroy@google.com>
Signed-off-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NSoheil Hassas Yeganeh <soheil@google.com>
Signed-off-by: NJakub Kicinski <kuba@kernel.org>

Sometimes, we may call tcp receive zerocopy when inq is 0,
or inq < PAGE_SIZE, in which case we cannot remap pages. In this case,
simply return the appropriate hint for regular copying without taking
mmap_sem.
Signed-off-by: NArjun Roy <arjunroy@google.com>
Signed-off-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NSoheil Hassas Yeganeh <soheil@google.com>
Signed-off-by: NJakub Kicinski <kuba@kernel.org>