The SLINK controller found on Tegra30 is not compatible with its
predecessor found on Tegra20. Drop the fallback compatible string.
Signed-off-by: Thierry Reding <treding@nvidia.com>

The Ouya board specifies the #reset-cells property for the GPIO
controller. Since the GPIO controller doesn't provide reset controls
this is not needed, so they can be dropped.
Signed-off-by: Thierry Reding <treding@nvidia.com>

The clock-frequency property was never used and is deprecated now.
Remove it from Nexus 7 device-tree.
Signed-off-by: David Heidelberg <david@ixit.cz>
Signed-off-by: Thierry Reding <treding@nvidia.com>

The +V1.2_VDD_CORE regulator on Apalis and Colibri boards uses the
unsupported ti,vsel{0,1}-state-low properties. It turns out that these
are in fact the default and can be overridden by ti,vsel{0,1}-state-high
properties if needed. Drop them since they are not needed.
Signed-off-by: Thierry Reding <treding@nvidia.com>

The correct vendor prefix for Invensense is "invensense," rather than
"invn,".
Signed-off-by: Thierry Reding <treding@nvidia.com>

The Medcom Wide and PAZ00 boards don't specify the power supply for the
backlight, which means that the Linux driver will provide a dummy one.
Wire up an explicit dummy to also make the DT schema validation succeed.

Unfortunately I don't have access to the schematics for the Medcom Wide,
so I don't know if a more accurate description is possible.

The AC100 (PAZ00) schematics from here:

	https://www.s-manuals.com/pdf/motherboard/compal/compal_la-6352p_r1.0a_schematics.pdf

aren't entirely clear which one of the supplies powers backlight, but
the panel supply is probably close enough.

Based on work by David Heidelberg <david@ixit.cz>.
Signed-off-by: Thierry Reding <treding@nvidia.com>

The PHY reset GPIO references belong in the USB PHY nodes, where they
already exist. There is no need to keep them in the USB controller's
device tree node as well.
Signed-off-by: Thierry Reding <treding@nvidia.com>

The device tree node for the built-in ASIX Ethernet device on Colibri
boards needs a compatible string in order to pass DT schema validation.
Add the USB VID,PID compatible string as required by the DT schema for
USB devices.
Reviewed-by: Marcel Ziswiler <marcel.ziswiler@toradex.com>
Tested-by: Marcel Ziswiler <marcel.ziswiler@toradex.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>

The "pwm-" prefix currently matches the DT schema for PWM controllers
and throws an error in that case. This is something that should be fixed
in the PWM DT schema, but in this case we can also preempt any such
conflict by naming the nodes after the pins like we do for many others
of these nodes.
Signed-off-by: Thierry Reding <treding@nvidia.com>

Make the order of the clocks and clock-names properties match the order
in the device tree bindings. This isn't strictly necessary from a point
of view of the operating system because matching will be done based on
the clock-names, but it makes it easier to validate the device trees
against the DT schema.
Signed-off-by: Thierry Reding <treding@nvidia.com>

The CML1 and PLL_E clocks are never explicitly used by the AHCI
controller found on Tegra124, so drop them from the corresponding device
tree node.
Signed-off-by: Thierry Reding <treding@nvidia.com>

The I2C controller found on Tegra124 is not fully compatible with the
Tegra114 version, so drop the fallback compatible string from the list.
Signed-off-by: Thierry Reding <treding@nvidia.com>

OPP table name now should start with "opp-table" and OPP entries
shouldn't contain commas and @ signs in accordance to the new schema
requirement. Reorganize CPU and EMC OPP table device-tree nodes.
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>

The DT schema requires that nodes representing thermal zones include a
"-thermal" suffix in their name.
Signed-off-by: Thierry Reding <treding@nvidia.com>

When the Tegra High-Speed UART is used instead of the regular UART, the
reg-shift property is implied from the compatible string and should not
be explicitly listed.
Signed-off-by: Thierry Reding <treding@nvidia.com>

In order to be able to pass DT schema validation, change the GPU nodes'
unit-address to the standard notation. Previously this was using a "0,"
prefix that originated from a time when the top-level device tree node
contained #address-cells = <2>.

Note that this technically breaks backwards-compatibility with certain
older versions of the U-Boot bootloader because early versions used a
hard-coded DT path lookup to find the GPU node and perform some fixups
on it. However, this was changed to a compatible string based lookup in
April 2016, so it's reasonable to expect people to update U-Boot on the
systems that they want to use this updated kernel DTB with.
Signed-off-by: Thierry Reding <treding@nvidia.com>

GPIO hog nodes must have a "hog-" prefix or "-hog" suffix according to
the DT schema. Rename all such nodes to allow validation to pass.
Signed-off-by: Thierry Reding <treding@nvidia.com>

The Tegra memory controller provides reset controls for hotflush reset,
so the #reset-cells property must be specified.
Signed-off-by: Thierry Reding <treding@nvidia.com>

The TKE (time-keeping engine) found on Tegra114 and later is no longer
backwards compatible with the version found on Tegra20, so update the
compatible string list accordingly.

Note that while the hardware block is strictly backwards-compatible, an
architectural timer exists on those newer SoCs that is more reliable, so
that should always be preferred.
Signed-off-by: Thierry Reding <treding@nvidia.com>

Regulators defined at the top level in device tree are no longer part of
a simple bus and therefore don't have a reg property. Nodes without a
reg property shouldn't have a unit-address either, so drop the unit
address from the node names. To ensure nodes aren't duplicated (in which
case they would end up merged in the final DTB), append the name of the
regulator to the node name.

[treding@nvidia.com: factored out patch and wrote commit message]
Signed-off-by: David Heidelberg <david@ixit.cz>
Co-developed-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>

Clocks defined at the top level in device tree are no longer part of a
simple bus and therefore don't have a reg property. Nodes without a reg
property shouldn't have a unit-address either, so drop the unit address
from the node names. To ensure nodes aren't duplicated (in which case
they would end up merged in the final DTB), append the name of the clock
to the node name.

[treding@nvidia.com: factored out patch and wrote commit message]
Signed-off-by: David Heidelberg <david@ixit.cz>
Co-developed-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>

SPI flash chip nodes should be named "flash" instead of "spi-flash".
Signed-off-by: Thierry Reding <treding@nvidia.com>

The PMIC found on Dalmore, TN7 and Roth is a TPS65913, so add the
specific compatible string in addition to the generic Palmas series
compatible string.
Signed-off-by: Thierry Reding <treding@nvidia.com>

The external memory controller should be sorted after the memory
controller to keep the ordering by unit-address intact.
Signed-off-by: Thierry Reding <treding@nvidia.com>

Add Kconfig support for -Wimplicit-fallthrough for both GCC and Clang.

The compiler option is under configuration CC_IMPLICIT_FALLTHROUGH,
which is enabled by default.

Special thanks to Nathan Chancellor who fixed the Clang bug[1][2]. This
bugfix only appears in Clang 14.0.0, so older versions still contain
the bug and -Wimplicit-fallthrough won't be enabled for them, for now.

This concludes a long journey and now we are finally getting rid
of the unintentional fallthrough bug-class in the kernel, entirely. :)

Link: https://github.com/llvm/llvm-project/commit/9ed4a94d6451046a51ef393cd62f00710820a7e8 [1]
Link: https://bugs.llvm.org/show_bug.cgi?id=51094 [2]
Link: https://github.com/KSPP/linux/issues/115
Link: https://github.com/ClangBuiltLinux/linux/issues/236Co-developed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Co-developed-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Pull xfs cleanups from Darrick Wong:
 "The most 'exciting' aspect of this branch is that the xfsprogs
  maintainer and I have worked through the last of the code
  discrepancies between kernel and userspace libxfs such that there are
  no code differences between the two except for #includes.

  IOWs, diff suffices to demonstrate that the userspace tools behave the
  same as the kernel, and kernel-only bits are clearly marked in the
  /kernel/ source code instead of just the userspace source.

  Summary:

   - Clean up open-coded swap() calls.

   - A little bit of #ifdef golf to complete the reunification of the
     kernel and userspace libxfs source code"

* tag 'xfs-5.16-merge-5' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux:
  xfs: sync xfs_btree_split macros with userspace libxfs
  xfs: #ifdef out perag code for userspace
  xfs: use swap() to make dabtree code cleaner

Pull more parisc fixes from Helge Deller:
 "Fix a build error in stracktrace.c, fix resolving of addresses to
  function names in backtraces, fix single-stepping in assembly code and
  flush userspace pte's when using set_pte_at()"

* tag 'for-5.16/parisc-3' of git://git.kernel.org/pub/scm/linux/kernel/git/deller/parisc-linux:
  parisc/entry: fix trace test in syscall exit path
  parisc: Flush kernel data mapping in set_pte_at() when installing pte for user page
  parisc: Fix implicit declaration of function '__kernel_text_address'
  parisc: Fix backtrace to always include init funtion names

Pull arch/sh updates from Rich Felker.

* tag 'sh-for-5.16' of git://git.libc.org/linux-sh:
  sh: pgtable-3level: Fix cast to pointer from integer of different size
  sh: fix READ/WRITE redefinition warnings
  sh: define __BIG_ENDIAN for math-emu
  sh: math-emu: drop unused functions
  sh: fix kconfig unmet dependency warning for FRAME_POINTER
  sh: Cleanup about SPARSE_IRQ
  sh: kdump: add some attribute to function
  maple: fix wrong return value of maple_bus_init().
  sh: boot: avoid unneeded rebuilds under arch/sh/boot/compressed/
  sh: boot: add intermediate vmlinux.bin* to targets instead of extra-y
  sh: boards: Fix the cacography in irq.c
  sh: check return code of request_irq
  sh: fix trivial misannotations

Pull ARM fixes from Russell King:

 - Fix early_iounmap

 - Drop cc-option fallbacks for architecture selection

* tag 'for-linus' of git://git.armlinux.org.uk/~rmk/linux-arm:
  ARM: 9156/1: drop cc-option fallbacks for architecture selection
  ARM: 9155/1: fix early early_iounmap()

Pull devicetree fixes from Rob Herring:

 - Two fixes due to DT node name changes on Arm, Ltd. boards

 - Treewide rename of Ingenic CGU headers

 - Update ST email addresses

 - Remove Netlogic DT bindings

 - Dropping few more cases of redundant 'maxItems' in schemas

 - Convert toshiba,tc358767 bridge binding to schema

* tag 'devicetree-fixes-for-5.16-1' of git://git.kernel.org/pub/scm/linux/kernel/git/robh/linux:
  dt-bindings: watchdog: sunxi: fix error in schema
  bindings: media: venus: Drop redundant maxItems for power-domain-names
  dt-bindings: Remove Netlogic bindings
  clk: versatile: clk-icst: Ensure clock names are unique
  of: Support using 'mask' in making device bus id
  dt-bindings: treewide: Update @st.com email address to @foss.st.com
  dt-bindings: media: Update maintainers for st,stm32-hwspinlock.yaml
  dt-bindings: media: Update maintainers for st,stm32-cec.yaml
  dt-bindings: mfd: timers: Update maintainers for st,stm32-timers
  dt-bindings: timer: Update maintainers for st,stm32-timer
  dt-bindings: i2c: imx: hardware do not restrict clock-frequency to only 100 and 400 kHz
  dt-bindings: display: bridge: Convert toshiba,tc358767.txt to yaml
  dt-bindings: Rename Ingenic CGU headers to ingenic,*.h

Pull timer fix from Thomas Gleixner:
 "A single fix for POSIX CPU timers to address a problem where POSIX CPU
  timer delivery stops working for a new child task because
  copy_process() copies state information which is only valid for the
  parent task"

* tag 'timers-urgent-2021-11-14' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  posix-cpu-timers: Clear task::posix_cputimers_work in copy_process()

Pull irq fixes from Thomas Gleixner:
 "A set of fixes for the interrupt subsystem

  Core code:

   - A regression fix for the Open Firmware interrupt mapping code where
     a interrupt controller property in a node caused a map property in
     the same node to be ignored.

  Interrupt chip drivers:

   - Workaround a limitation in SiFive PLIC interrupt chip which
     silently ignores an EOI when the interrupt line is masked.

   - Provide the missing mask/unmask implementation for the CSKY MP
     interrupt controller.

  PCI/MSI:

   - Prevent a use after free when PCI/MSI interrupts are released by
     destroying the sysfs entries before freeing the memory which is
     accessed in the sysfs show() function.

   - Implement a mask quirk for the Nvidia ION AHCI chip which does not
     advertise masking capability despite implementing it. Even worse
     the chip comes out of reset with all MSI entries masked, which due
     to the missing masking capability never get unmasked.

   - Move the check which prevents accessing the MSI[X] masking for XEN
     back into the low level accessors. The recent consolidation missed
     that these accessors can be invoked from places which do not have
     that check which broke XEN. Move them back to he original place
     instead of sprinkling tons of these checks all over the code"

* tag 'irq-urgent-2021-11-14' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  of/irq: Don't ignore interrupt-controller when interrupt-map failed
  irqchip/sifive-plic: Fixup EOI failed when masked
  irqchip/csky-mpintc: Fixup mask/unmask implementation
  PCI/MSI: Destroy sysfs before freeing entries
  PCI: Add MSI masking quirk for Nvidia ION AHCI
  PCI/MSI: Deal with devices lying about their MSI mask capability
  PCI/MSI: Move non-mask check back into low level accessors

Pull x86 static call update from Thomas Gleixner:
 "A single fix for static calls to make the trampoline patching more
  robust by placing explicit signature bytes after the call trampoline
  to prevent patching random other jumps like the CFI jump table
  entries"

* tag 'locking-urgent-2021-11-14' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  static_call,x86: Robustify trampoline patching

Pull scheduler fixes from Borislav Petkov:

 - Avoid touching ~100 config files in order to be able to select the
   preemption model

 - clear cluster CPU masks too, on the CPU unplug path

 - prevent use-after-free in cfs

 - Prevent a race condition when updating CPU cache domains

 - Factor out common shared part of smp_prepare_cpus() into a common
   helper which can be called by both baremetal and Xen, in order to fix
   a booting of Xen PV guests

* tag 'sched_urgent_for_v5.16_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  preempt: Restore preemption model selection configs
  arch_topology: Fix missing clear cluster_cpumask in remove_cpu_topology()
  sched/fair: Prevent dead task groups from regaining cfs_rq's
  sched/core: Mitigate race cpus_share_cache()/update_top_cache_domain()
  x86/smp: Factor out parts of native_smp_prepare_cpus()

Pull perf fixes from Borislav Petkov:

 - Prevent unintentional page sharing by checking whether a page
   reference to a PMU samples page has been acquired properly before
   that

 - Make sure the LBR_SELECT MSR is saved/restored too

 - Reset the LBR_SELECT MSR when resetting the LBR PMU to clear any
   residual data left

* tag 'perf_urgent_for_v5.16_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  perf/core: Avoid put_page() when GUP fails
  perf/x86/vlbr: Add c->flags to vlbr event constraints
  perf/x86/lbr: Reset LBR_SELECT during vlbr reset

Pull x86 fixes from Borislav Petkov:

 - Add the model number of a new, Raptor Lake CPU, to intel-family.h

 - Do not log spurious corrected MCEs on SKL too, due to an erratum

 - Clarify the path of paravirt ops patches upstream

 - Add an optimization to avoid writing out AMX components to sigframes
   when former are in init state

* tag 'x86_urgent_for_v5.16_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/cpu: Add Raptor Lake to Intel family
  x86/mce: Add errata workaround for Skylake SKX37
  MAINTAINERS: Add some information to PARAVIRT_OPS entry
  x86/fpu: Optimize out sigframe xfeatures when in init state

Merge tag 'perf-tools-for-v5.16-2021-11-13' of git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux

Pull more perf tools updates from Arnaldo Carvalho de Melo:
 "Hardware tracing:

   - ARM:
      * Print the size of the buffer size consistently in hexadecimal in
        ARM Coresight.
      * Add Coresight snapshot mode support.
      * Update --switch-events docs in 'perf record'.
      * Support hardware-based PID tracing.
      * Track task context switch for cpu-mode events.

   - Vendor events:
      * Add metric events JSON file for power10 platform

  perf test:

   - Get 'perf test' unit tests closer to kunit.

   - Topology tests improvements.

   - Remove bashisms from some tests.

  perf bench:

   - Fix memory leak of perf_cpu_map__new() in the futex benchmarks.

  libbpf:

   - Add some more weak libbpf functions o allow building with the
     libbpf versions, old ones, present in distros.

  libbeauty:

   - Translate [gs]setsockopt 'level' argument integer values to
     strings.

  tools headers UAPI:

   - Sync futex_waitv, arch prctl, sound, i195_drm and msr-index files
     with the kernel sources.

  Documentation:

   - Add documentation to 'struct symbol'.

   - Synchronize the definition of enum perf_hw_id with code in
     tools/perf/design.txt"

* tag 'perf-tools-for-v5.16-2021-11-13' of git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux: (67 commits)
  perf tests: Remove bash constructs from stat_all_pmu.sh
  perf tests: Remove bash construct from record+zstd_comp_decomp.sh
  perf test: Remove bash construct from stat_bpf_counters.sh test
  perf bench futex: Fix memory leak of perf_cpu_map__new()
  tools arch x86: Sync the msr-index.h copy with the kernel sources
  tools headers UAPI: Sync drm/i915_drm.h with the kernel sources
  tools headers UAPI: Sync sound/asound.h with the kernel sources
  tools headers UAPI: Sync linux/prctl.h with the kernel sources
  tools headers UAPI: Sync arch prctl headers with the kernel sources
  perf tools: Add more weak libbpf functions
  perf bpf: Avoid memory leak from perf_env__insert_btf()
  perf symbols: Factor out annotation init/exit
  perf symbols: Bit pack to save a byte
  perf symbols: Add documentation to 'struct symbol'
  tools headers UAPI: Sync files changed by new futex_waitv syscall
  perf test bpf: Use ARRAY_CHECK() instead of ad-hoc equivalent, addressing array_size.cocci warning
  perf arm-spe: Support hardware-based PID tracing
  perf arm-spe: Save context ID in record
  perf arm-spe: Update --switch-events docs in 'perf record'
  perf arm-spe: Track task context switch for cpu-mode events
  ...

Merge tag 'irqchip-fixes-5.16-1' of git://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms into irq/urgent

Pull irqchip fixes from Marc Zyngier:

  - Address an issue with the SiFive PLIC being unable to EOI
    a masked interrupt

  - Move the disable/enable methods in the CSky mpintc to
    mask/unmask

  - Fix a regression in the OF irq code where an interrupt-controller
    property in the same node as an interrupt-map property would get
    ignored

Link: https://lore.kernel.org/all/20211112173459.4015233-1-maz@kernel.org

Pull zstd update from Nick Terrell:
 "Update to zstd-1.4.10.

  Add myself as the maintainer of zstd and update the zstd version in
  the kernel, which is now 4 years out of date, to a much more recent
  zstd release. This includes bug fixes, much more extensive fuzzing,
  and performance improvements. And generates the kernel zstd
  automatically from upstream zstd, so it is easier to keep the zstd
  verison up to date, and we don't fall so far out of date again.

  This includes 5 commits that update the zstd library version:

   - Adds a new kernel-style wrapper around zstd.

     This wrapper API is functionally equivalent to the subset of the
     current zstd API that is currently used. The wrapper API changes to
     be kernel style so that the symbols don't collide with zstd's
     symbols. The update to zstd-1.4.10 maintains the same API and
     preserves the semantics, so that none of the callers need to be
     updated. All callers are updated in the commit, because there are
     zero functional changes.

   - Adds an indirection for `lib/decompress_unzstd.c` so it doesn't
     depend on the layout of `lib/zstd/` to include every source file.
     This allows the next patch to be automatically generated.

   - Imports the zstd-1.4.10 source code. This commit is automatically
     generated from upstream zstd (https://github.com/facebook/zstd).

   - Adds me (terrelln@fb.com) as the maintainer of `lib/zstd`.

   - Fixes a newly added build warning for clang.

  The discussion around this patchset has been pretty long, so I've
  included a FAQ-style summary of the history of the patchset, and why
  we are taking this approach.

  Why do we need to update?
  -------------------------

  The zstd version in the kernel is based off of zstd-1.3.1, which is
  was released August 20, 2017. Since then zstd has seen many bug fixes
  and performance improvements. And, importantly, upstream zstd is
  continuously fuzzed by OSS-Fuzz, and bug fixes aren't backported to
  older versions. So the only way to sanely get these fixes is to keep
  up to date with upstream zstd.

  There are no known security issues that affect the kernel, but we need
  to be able to update in case there are. And while there are no known
  security issues, there are relevant bug fixes. For example the problem
  with large kernel decompression has been fixed upstream for over 2
  years [1]

  Additionally the performance improvements for kernel use cases are
  significant. Measured for x86_64 on my Intel i9-9900k @ 3.6 GHz:

   - BtrFS zstd compression at levels 1 and 3 is 5% faster

   - BtrFS zstd decompression+read is 15% faster

   - SquashFS zstd decompression+read is 15% faster

   - F2FS zstd compression+write at level 3 is 8% faster

   - F2FS zstd decompression+read is 20% faster

   - ZRAM decompression+read is 30% faster

   - Kernel zstd decompression is 35% faster

   - Initramfs zstd decompression+build is 5% faster

  On top of this, there are significant performance improvements coming
  down the line in the next zstd release, and the new automated update
  patch generation will allow us to pull them easily.

  How is the update patch generated?
  ----------------------------------

  The first two patches are preparation for updating the zstd version.
  Then the 3rd patch in the series imports upstream zstd into the
  kernel. This patch is automatically generated from upstream. A script
  makes the necessary changes and imports it into the kernel. The
  changes are:

   - Replace all libc dependencies with kernel replacements and rewrite
     includes.

   - Remove unncessary portability macros like: #if defined(_MSC_VER).

   - Use the kernel xxhash instead of bundling it.

  This automation gets tested every commit by upstream's continuous
  integration. When we cut a new zstd release, we will submit a patch to
  the kernel to update the zstd version in the kernel.

  The automated process makes it easy to keep the kernel version of zstd
  up to date. The current zstd in the kernel shares the guts of the
  code, but has a lot of API and minor changes to work in the kernel.
  This is because at the time upstream zstd was not ready to be used in
  the kernel envrionment as-is. But, since then upstream zstd has
  evolved to support being used in the kernel as-is.

  Why are we updating in one big patch?
  -------------------------------------

  The 3rd patch in the series is very large. This is because it is
  restructuring the code, so it both deletes the existing zstd, and
  re-adds the new structure. Future updates will be directly
  proportional to the changes in upstream zstd since the last import.
  They will admittidly be large, as zstd is an actively developed
  project, and has hundreds of commits between every release. However,
  there is no other great alternative.

  One option ruled out is to replay every upstream zstd commit. This is
  not feasible for several reasons:

   - There are over 3500 upstream commits since the zstd version in the
     kernel.

   - The automation to automatically generate the kernel update was only
     added recently, so older commits cannot easily be imported.

   - Not every upstream zstd commit builds.

   - Only zstd releases are "supported", and individual commits may have
     bugs that were fixed before a release.

  Another option to reduce the patch size would be to first reorganize
  to the new file structure, and then apply the patch. However, the
  current kernel zstd is formatted with clang-format to be more
  "kernel-like". But, the new method imports zstd as-is, without
  additional formatting, to allow for closer correlation with upstream,
  and easier debugging. So the patch wouldn't be any smaller.

  It also doesn't make sense to import upstream zstd commit by commit
  going forward. Upstream zstd doesn't support production use cases
  running of the development branch. We have a lot of post-commit
  fuzzing that catches many bugs, so indiviudal commits may be buggy,
  but fixed before a release. So going forward, I intend to import every
  (important) zstd release into the Kernel.

  So, while it isn't ideal, updating in one big patch is the only patch
  I see forward.

  Who is responsible for this code?
  ---------------------------------

  I am. This patchset adds me as the maintainer for zstd. Previously,
  there was no tree for zstd patches. Because of that, there were
  several patches that either got ignored, or took a long time to merge,
  since it wasn't clear which tree should pick them up. I'm officially
  stepping up as maintainer, and setting up my tree as the path through
  which zstd patches get merged. I'll make sure that patches to the
  kernel zstd get ported upstream, so they aren't erased when the next
  version update happens.

  How is this code tested?
  ------------------------

  I tested every caller of zstd on x86_64 (BtrFS, ZRAM, SquashFS, F2FS,
  Kernel, InitRAMFS). I also tested Kernel & InitRAMFS on i386 and
  aarch64. I checked both performance and correctness.

  Also, thanks to many people in the community who have tested these
  patches locally.

  Lastly, this code will bake in linux-next before being merged into
  v5.16.

  Why update to zstd-1.4.10 when zstd-1.5.0 has been released?
  ------------------------------------------------------------

  This patchset has been outstanding since 2020, and zstd-1.4.10 was the
  latest release when it was created. Since the update patch is
  automatically generated from upstream, I could generate it from
  zstd-1.5.0.

  However, there were some large stack usage regressions in zstd-1.5.0,
  and are only fixed in the latest development branch. And the latest
  development branch contains some new code that needs to bake in the
  fuzzer before I would feel comfortable releasing to the kernel.

  Once this patchset has been merged, and we've released zstd-1.5.1, we
  can update the kernel to zstd-1.5.1, and exercise the update process.

  You may notice that zstd-1.4.10 doesn't exist upstream. This release
  is an artifical release based off of zstd-1.4.9, with some fixes for
  the kernel backported from the development branch. I will tag the
  zstd-1.4.10 release after this patchset is merged, so the Linux Kernel
  is running a known version of zstd that can be debugged upstream.

  Why was a wrapper API added?
  ----------------------------

  The first versions of this patchset migrated the kernel to the
  upstream zstd API. It first added a shim API that supported the new
  upstream API with the old code, then updated callers to use the new
  shim API, then transitioned to the new code and deleted the shim API.
  However, Cristoph Hellwig suggested that we transition to a kernel
  style API, and hide zstd's upstream API behind that. This is because
  zstd's upstream API is supports many other use cases, and does not
  follow the kernel style guide, while the kernel API is focused on the
  kernel's use cases, and follows the kernel style guide.

  Where is the previous discussion?
  ---------------------------------

  Links for the discussions of the previous versions of the patch set
  below. The largest changes in the design of the patchset are driven by
  the discussions in v11, v5, and v1. Sorry for the mix of links, I
  couldn't find most of the the threads on lkml.org"

Link: https://lkml.org/lkml/2020/9/29/27 [1]
Link: https://www.spinics.net/lists/linux-crypto/msg58189.html [v12]
Link: https://lore.kernel.org/linux-btrfs/20210430013157.747152-1-nickrterrell@gmail.com/ [v11]
Link: https://lore.kernel.org/lkml/20210426234621.870684-2-nickrterrell@gmail.com/ [v10]
Link: https://lore.kernel.org/linux-btrfs/20210330225112.496213-1-nickrterrell@gmail.com/ [v9]
Link: https://lore.kernel.org/linux-f2fs-devel/20210326191859.1542272-1-nickrterrell@gmail.com/ [v8]
Link: https://lkml.org/lkml/2020/12/3/1195 [v7]
Link: https://lkml.org/lkml/2020/12/2/1245 [v6]
Link: https://lore.kernel.org/linux-btrfs/20200916034307.2092020-1-nickrterrell@gmail.com/ [v5]
Link: https://www.spinics.net/lists/linux-btrfs/msg105783.html [v4]
Link: https://lkml.org/lkml/2020/9/23/1074 [v3]
Link: https://www.spinics.net/lists/linux-btrfs/msg105505.html [v2]
Link: https://lore.kernel.org/linux-btrfs/20200916034307.2092020-1-nickrterrell@gmail.com/ [v1]
Signed-off-by: Nick Terrell <terrelln@fb.com>
Tested By: Paul Jones <paul@pauljones.id.au>
Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com> # LLVM/Clang v13.0.0 on x86-64
Tested-by: Jean-Denis Girard <jd.girard@sysnux.pf>

* tag 'zstd-for-linus-v5.16' of git://github.com/terrelln/linux:
  lib: zstd: Add cast to silence clang's -Wbitwise-instead-of-logical
  MAINTAINERS: Add maintainer entry for zstd
  lib: zstd: Upgrade to latest upstream zstd version 1.4.10
  lib: zstd: Add decompress_sources.h for decompress_unzstd
  lib: zstd: Add kernel-specific API