docs: add more netlink docs (incl. spec docs)

Add documentation about the upcoming Netlink protocol specs.

Reviewed-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Reviewed-by: Bagas Sanjaya <bagasdotme@gmail.com>
Acked-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

Maple Tree: add new data structure

Patch series "Introducing the Maple Tree"

The maple tree is an RCU-safe range based B-tree designed to use modern
processor cache efficiently. There are a number of places in the kernel
that a non-overlapping range-based tree would be beneficial, especially
one with a simple interface. If you use an rbtree with other data
structures to improve performance or an interval tree to track
non-overlapping ranges, then this is for you.

The tree has a branching factor of 10 for non-leaf nodes and 16 for leaf
nodes. With the increased branching factor, it is significantly shorter
than the rbtree so it has fewer cache misses. The removal of the linked
list between subsequent entries also reduces the cache misses and the need
to pull in the previous and next VMA during many tree alterations.

The first user that is covered in this patch set is the vm_area_struct,
where three data structures are replaced by the maple tree: the augmented
rbtree, the vma cache, and the linked list of VMAs in the mm_struct. The
long term goal is to reduce or remove the mmap_lock contention.

The plan is to get to the point where we use the maple tree in RCU mode.
Readers will not block for writers. A single write operation will be
allowed at a time. A reader re-walks if stale data is encountered. VMAs
would be RCU enabled and this mode would be entered once multiple tasks
are using the mm_struct.

Davidlor said

: Yes I like the maple tree, and at this stage I don't think we can ask for
: more from this series wrt the MM - albeit there seems to still be some
: folks reporting breakage. Fundamentally I see Liam's work to (re)move
: complexity out of the MM (not to say that the actual maple tree is not
: complex) by consolidating the three complimentary data structures very
: much worth it considering performance does not take a hit. This was very
: much a turn off with the range locking approach, which worst case scenario
: incurred in prohibitive overhead. Also as Liam and Matthew have
: mentioned, RCU opens up a lot of nice performance opportunities, and in
: addition academia[1] has shown outstanding scalability of address spaces
: with the foundation of replacing the locked rbtree with RCU aware trees.

A similar work has been discovered in the academic press

https://pdos.csail.mit.edu/papers/rcuvm:asplos12.pdf

Sheer coincidence. We designed our tree with the intention of solving the
hardest problem first. Upon settling on a b-tree variant and a rough
outline, we researched ranged based b-trees and RCU b-trees and did find
that article. So it was nice to find reassurances that we were on the
right path, but our design choice of using ranges made that paper unusable
for us.

This patch (of 70):

The maple tree is an RCU-safe range based B-tree designed to use modern
processor cache efficiently. There are a number of places in the kernel
that a non-overlapping range-based tree would be beneficial, especially
one with a simple interface. If you use an rbtree with other data
structures to improve performance or an interval tree to track
non-overlapping ranges, then this is for you.

The tree has a branching factor of 10 for non-leaf nodes and 16 for leaf
nodes. With the increased branching factor, it is significantly shorter
than the rbtree so it has fewer cache misses. The removal of the linked
list between subsequent entries also reduces the cache misses and the need
to pull in the previous and next VMA during many tree alterations.

The first user that is covered in this patch set is the vm_area_struct,
where three data structures are replaced by the maple tree: the augmented
rbtree, the vma cache, and the linked list of VMAs in the mm_struct. The
long term goal is to reduce or remove the mmap_lock contention.

The plan is to get to the point where we use the maple tree in RCU mode.
Readers will not block for writers. A single write operation will be
allowed at a time. A reader re-walks if stale data is encountered. VMAs
would be RCU enabled and this mode would be entered once multiple tasks
are using the mm_struct.

There is additional BUG_ON() calls added within the tree, most of which
are in debug code. These will be replaced with a WARN_ON() call in the
future. There is also additional BUG_ON() calls within the code which
will also be reduced in number at a later date. These exist to catch
things such as out-of-range accesses which would crash anyways.

Link: https://lkml.kernel.org/r/20220906194824.2110408-1-Liam.Howlett@oracle.com
Link: https://lkml.kernel.org/r/20220906194824.2110408-2-Liam.Howlett@oracle.com
Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Tested-by: David Howells <dhowells@redhat.com>
Tested-by: Sven Schnelle <svens@linux.ibm.com>
Tested-by: Yu Zhao <yuzhao@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: David Hildenbrand <david@redhat.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: SeongJae Park <sj@kernel.org>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

docs: put atomic*.txt and memory-barriers.txt into the core-api book

These files describe part of the core API, but have never been converted to
RST due to ... let's say local oppposition. So, create a set of
special-purpose wrappers to ..include these files into a separate page so
that they can be a part of the htmldocs build. Then link them into the
core-api manual and remove them from the "staging" dumping ground.

Acked-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Reviewed-by: David Vernet <void@manifault.com>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Link: https://lore.kernel.org/r/20220927160559.97154-7-corbet@lwn.net
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

docs: move asm-annotations.rst into core-api

This one file should not really be in the top-level documentation
directory. core-api/ may not be a perfect fit but seems to be best, so
move it there. Adjust a couple of internal document references to make
them location-independent, and point checkpatch.pl at the new location.

Cc: Jiri Slaby <jirislaby@kernel.org>
Cc: Joe Perches <joe@perches.com>
Reviewed-by: David Vernet <void@manifault.com>
Acked-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Link: https://lore.kernel.org/r/20220927160559.97154-6-corbet@lwn.net
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

arch/*/: remove CONFIG_VIRT_TO_BUS

All architecture-independent users of virt_to_bus() and bus_to_virt()
have been fixed to use the dma mapping interfaces or have been
removed now. This means the definitions on most architectures, and the
CONFIG_VIRT_TO_BUS symbol are now obsolete and can be removed.

The only exceptions to this are a few network and scsi drivers for m68k
Amiga and VME machines and ppc32 Macintosh. These drivers work correctly
with the old interfaces and are probably not worth changing.

On alpha and parisc, virt_to_bus() were still used in asm/floppy.h.
alpha can use isa_virt_to_bus() like x86 does, and parisc can just
open-code the virt_to_phys() here, as this is architecture specific
code.

I tried updating the bus-virt-phys-mapping.rst documentation, which
started as an email from Linus to explain some details of the Linux-2.0
driver interfaces. The bits about virt_to_bus() were declared obsolete
backin 2000, and the rest is not all that relevant any more, so in the
end I just decided to remove the file completely.

Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)
Acked-by: Helge Deller <deller@gmx.de> # parisc
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

docs: rename Documentation/vm to Documentation/mm

so it will be consistent with code mm directory and with
Documentation/admin-guide/mm and won't be confused with virtual machines.

Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Suggested-by: Matthew Wilcox <willy@infradead.org>
Tested-by: Ira Weiny <ira.weiny@intel.com>
Acked-by: Jonathan Corbet <corbet@lwn.net>
Acked-by: Wu XiangCheng <bobwxc@email.cn>

Documentation: move watch_queue to core-api

Move watch_queue documentation to the core-api index and
subdirectory.

Fixes: c73be61cede5 ("pipe: Add general notification queue support")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: David Howells <dhowells@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: linux-doc@vger.kernel.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

printk/index: Printk index feature documentation

Document the printk index feature. The primary motivation is to
explain that it is not creating KABI from particular printk() calls.

Acked-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Reviewed-by: Chris Down <chris@chrisdown.name>
Signed-off-by: Petr Mladek <pmladek@suse.com>

Documentation: Fill the gaps about entry/noinstr constraints

The entry/exit handling for exceptions, interrupts, syscalls and KVM is
not really documented except for some comments.

Fill the gaps.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de
Co-developed-by: Nicolas Saenz Julienne <nsaenzju@redhat.com>
Signed-off-by: Nicolas Saenz Julienne <nsaenzju@redhat.com>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Paul E. McKenney <paulmck@kernel.org>

----

Changes since v3:
- s/nointr/noinstr/

Changes since v2:
- No big content changes, just style corrections, so it should be
pretty clean at this stage. In the light of this, I kept Mark's
Reviewed-by.
- Paul's style and paragraph re-writes
- Randy's style comments
- Add links to transition type sections

Documentation/core-api/entry.rst | 261 +++++++++++++++++++++++++++++++
Documentation/core-api/index.rst | 8 +
2 files changed, 269 insertions(+)
create mode 100644 Documentation/core-api/entry.rst

Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://lore.kernel.org/r/20220110105044.94423-1-nsaenzju@redhat.com
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

docs: core-api: avoid using ReST :doc:`foo` markup

The :doc:`foo` tag is auto-generated via automarkup.py.
So, use the filename at the sources, instead of :doc:`foo`.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/d967d490b6655735b7df292f88859b5a1b07d0d7.1623824363.git.mchehab+huawei@kernel.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

atomic: remove further references to atomic_ops

Commit f0400a77ebdc ("atomic: Delete obsolete documentation") removed
./Documentation/core-api/atomic_ops.rst, but missed to remove further
references to that file.

Hence, make htmldocs warns:

Documentation/core-api/index.rst:53: WARNING:
toctree contains reference to nonexisting document 'core-api/atomic_ops'

Also, ./scripts/get_maintainer.pl --self-test=patterns warns:

warning: no file matches F: Documentation/core-api/atomic_ops.rst

Remove further references to ./Documentation/core-api/atomic_ops.rst.

Fixes: f0400a77ebdc ("atomic: Delete obsolete documentation")
Signed-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Link: https://lore.kernel.org/r/20201220060927.21582-1-lukas.bulwahn@gmail.com
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

docs: move other kAPI documents to core-api

There are a number of random documents that seem to be
describing some aspects of the core-api. Move them to such
directory, adding them at the core-api/index.rst file.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/86d979ed183adb76af93a92f20189bccf97f0055.1592918949.git.mchehab+huawei@kernel.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

docs: move the kref doc into the core-api book

This document covers core kernel objects. So, add it into the core-api
book.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/f385af13b4a6d3ff8c89beedd4506900e79ca72e.1588345503.git.mchehab+huawei@kernel.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

docs: add IRQ documentation at the core-api book

There are 4 IRQ documentation files under Documentation/*.txt.

Move them into a new directory (core-api/irq) and add a new
index file for it.

While here, use a title markup for the Debugging section of the
irq-domain.rst file.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/2da7485c3718e1442e6b4c2dd66857b776e8899b.1588345503.git.mchehab+huawei@kernel.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

docs: debugging-via-ohci1394.txt: add it to the core-api book

There is an special chapter inside the core-api book about
some debug infrastructure like tracepoints and debug objects.

It sounded to me that this is the best place to add a chapter
explaining how to use a FireWire controller to do remote
kernel debugging, as explained on this document.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/9b489d36d08ad89d3ad5aefef1f52a0715b29716.1588345503.git.mchehab+huawei@kernel.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

docs: move DMA kAPI to Documentation/core-api

Move those files to the core-api, where they belong, renaming
them to ReST and adding to the core API index file.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/a1517185418cb9d987f566ef85a5dd5c7c99f34e.1588345503.git.mchehab+huawei@kernel.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

docs: Add rbtree documentation to the core-api

This file is close enough to being in rst format that I didn't feel
the need to alter it in any way.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Acked-by: Michel Lespinasse <walken@google.com>
Link: https://lore.kernel.org/r/20200401173343.17472-1-willy@infradead.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

docs: pr_*() kerneldocs and basic printk docs

Add kerneldocs comments to the pr_*() macros in printk.h.

Add a new rst node in the core-api manual describing the basic usage of
printk and the related macro aliases.

Signed-off-by: Ricardo Cañuelo <ricardo.canuelo@collabora.com>
Link: https://lore.kernel.org/r/20200403093617.18003-1-ricardo.canuelo@collabora.com
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

docs: move core-api/ioctl.rst to driver-api/

The ioctl() documentation belongs with the rest of the driver-oriented
info, so move it there.

Signed-off-by: Jonathan Corbet <corbet@lwn.net>

docs: move gcc-plugins to the kbuild manual

Information about GCC plugins is relevant to kernel building, so move this
document to the kbuild manual.

Acked-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

docs: Organize core-api/index.rst

The core-api manual has become a big, disorganized mess. Try to bring a
small amount of order to it by organizing the documents into
subcategories.

Signed-off-by: Jonathan Corbet <corbet@lwn.net>

Documentation: kobject.txt has been moved to core-api/kobject.rst

Moved the `kobject.txt` to `core-api/kobject.rst` and updated the
`core-api` index to point to it.

Signed-off-by: Sameer Rahmani <lxsameer@gnu.org>
[jc: moved it down from the top of core-api/index.rst]
Link: https://lore.kernel.org/r/20200225222125.61874-2-lxsameer@gnu.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

mm/gup: introduce pin_user_pages*() and FOLL_PIN

Introduce pin_user_pages*() variations of get_user_pages*() calls, and
also pin_longterm_pages*() variations.

For now, these are placeholder calls, until the various call sites are
converted to use the correct get_user_pages*() or pin_user_pages*() API.

These variants will eventually all set FOLL_PIN, which is also
introduced, and thoroughly documented.

pin_user_pages()
pin_user_pages_remote()
pin_user_pages_fast()

All pages that are pinned via the above calls, must be unpinned via
put_user_page().

The underlying rules are:

* FOLL_PIN is a gup-internal flag, so the call sites should not directly
set it. That behavior is enforced with assertions.

* Call sites that want to indicate that they are going to do DirectIO
("DIO") or something with similar characteristics, should call a
get_user_pages()-like wrapper call that sets FOLL_PIN. These wrappers
will:

* Start with "pin_user_pages" instead of "get_user_pages". That
makes it easy to find and audit the call sites.

* Set FOLL_PIN

* For pages that are received via FOLL_PIN, those pages must be returned
via put_user_page().

Thanks to Jan Kara and Vlastimil Babka for explaining the 4 cases in
this documentation. (I've reworded it and expanded upon it.)

Link: http://lkml.kernel.org/r/20200107224558.2362728-12-jhubbard@nvidia.com
Signed-off-by: John Hubbard <jhubbard@nvidia.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Mike Rapoport <rppt@linux.ibm.com> [Documentation]
Reviewed-by: Jérôme Glisse <jglisse@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Alex Williamson <alex.williamson@redhat.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Cc: Björn Töpel <bjorn.topel@intel.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Cc: Jason Gunthorpe <jgg@mellanox.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Kirill A. Shutemov <kirill@shutemov.name>
Cc: Leon Romanovsky <leonro@mellanox.com>
Cc: Mauro Carvalho Chehab <mchehab@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Documentation: document ioctl interfaces better

Documentation/process/botching-up-ioctls.rst was orignally written as
a blog post for DRM driver writers, so it it misses some points while
going into a lot of detail on others.

Try to provide a replacement that addresses typical issues across a wider
range of subsystems, and follows the style of the core-api documentation
better.

Many improvements to the document are suggested by Ben Hutchings
<ben.hutchings@codethink.co.uk>, Jonathan Corbet <corbet@lwn.net> and
Geert Uytterhoeven <geert@linux-m68k.org>.

Reviewed-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

padata: update documentation

Remove references to unused functions, standardize language, update to
reflect new functionality, migrate to rst format, and fix all kernel-doc
warnings.

Fixes: 815613da6a67 ("kernel/padata.c: removed unused code")
Signed-off-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Cc: Eric Biggers <ebiggers@kernel.org>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Steffen Klassert <steffen.klassert@secunet.com>
Cc: linux-crypto@vger.kernel.org
Cc: linux-doc@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

doc: move namespaces.rst from kbuild/ to core-api/

We discussed a better location for this file, and agreed that
core-api/ is a good fit. Rename it to symbol-namespaces.rst
for disambiguation, and also add it to index.rst and MAINTAINERS.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: Matthias Maennich <maennich@google.com>
Signed-off-by: Jessica Yu <jeyu@kernel.org>

docs: index.rst: don't use genindex for pdf output

The genindex logic is meant to be used only for html output, as
pdf build has its own way to generate indexes.

Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Acked-by: Vinod Koul <vkoul@kernel.org> # dmaengine and soundwire
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

docs: packing: move it to core-api book and adjust markups

The packing.txt file was misplaced, as docs should be part of
a documentation book, and not at the root dir.

So, move it to the core-api directory and add to its index.

Also, ensure that the file will be properly parsed and the bitmap
ascii artwork will use a monotonic font.

Fixes: 554aae35007e ("lib: Add support for generic packing operations")
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Reviewed-by: Vladimir Oltean <olteanv@gmail.com>
Tested-by: Vladimir Oltean <olteanv@gmail.com>
Reviewed-by: Mike Rapoport <rppt@linux.ibm.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

docs: move gcc_plugins.txt to core-api and rename to .rst

The gcc_plugins.txt file is already a ReST file. Move it
to the core-api book while renaming it.

Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Acked-by: Kees Cook <keescook@chromium.org>

Add the RCU docs to the core-api manual

We should really move the RCU directory there as well, but that can wait
for another day.

Signed-off-by: Jonathan Corbet <corbet@lwn.net>

docs: move protection-keys.rst to the core-api book

This document is used by multiple architectures:

$ echo $(git grep -l pkey_mprotect arch|cut -d'/' -f 2|sort|uniq)
alpha arm arm64 ia64 m68k microblaze mips parisc powerpc s390 sh sparc x86 xtensa

So, let's move it to the core book and adjust the links to it
accordingly.

Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

docs: core-api: Drop reference to flexible-arrays

This file doesn't exist anymore.

Fixes: 586187d7de71 ("Drop flex_arrays")
Reviewed-by: Mukesh Ojha <mojha@codeaurora.org>
Signed-off-by: Jonathan Neuschäfer <j.neuschaefer@gmx.net>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

generic radix trees

Very simple radix tree implementation that supports storing arbitrary
size entries, up to PAGE_SIZE - upcoming patches will convert existing
flex_array users to genradixes. The new genradix code has a much
simpler API and implementation, and doesn't have a hard limit on the
number of elements like flex_array does.

Link: http://lkml.kernel.org/r/20181217131929.11727-5-kent.overstreet@gmail.com
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Eric Paris <eparis@parisplace.org>
Cc: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Neil Horman <nhorman@tuxdriver.com>
Cc: Paul Moore <paul@paul-moore.com>
Cc: Pravin B Shelar <pshelar@ovn.org>
Cc: Shaohua Li <shli@kernel.org>
Cc: Stephen Smalley <sds@tycho.nsa.gov>
Cc: Vlad Yasevich <vyasevich@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

xarray: Add documentation

This is documentation on how to use the XArray, not details about its
internal implementation.

Signed-off-by: Matthew Wilcox <willy@infradead.org>
Acked-by: Josef Bacik <jbacik@fb.com>

docs/core-api: rename memory-hotplug-notifier to memory-hotplug

to allow additions of new documentation about memory hotplug under the same
roof.

Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

docs/vm: split memory hotplug notifier description to Documentation/core-api

The memory hotplug notifier description is about kernel internals rather
than admin/user visible API. Place it appropriately.

Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

docs: core-api: add memory allocation guide

Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

docs/core-api: split memory management API to a separate file

This is basically copy-paste of the memory management section from
kernel-api.rst with some minor adjustments:

* The "User Space Memory Access" is moved to the beginning
* The get_user_pages_fast reference is now a part of "User Space Memory
Access"
* And, of course, headings are adjusted with section being promoted to
chapters

Link: http://lkml.kernel.org/r/1532626360-16650-6-git-send-email-rppt@linux.vnet.ibm.com
Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

docs/mm: add description of boot time memory management

Both bootmem and memblock are have pretty good internal documentation
coverage. With addition of some overview we get a nice description of the
early memory management.

Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

Documentation: document ktime_get_*() APIs

As Dave Chinner points out, we don't have a proper documentation for the
ktime_get() family of interfaces, making it rather unclear which of the
over 30 (!) interfaces one should actually use in a driver or elsewhere
in the kernel.

I wrote up an explanation from how I personally see the interfaces,
documenting what each of the functions do and hopefully making it a bit
clearer which should be used where.

This is the first time I tried writing .rst format documentation, so
in addition to any mistakes in the content, I probably also introduce
nonstandard formatting ;-)

I first tried to add an extra section to
Documentation/timers/timekeeping.txt, but this is currently not included
in the generated API, and it seems useful to have the API docs as part
of what gets generated in
https://www.kernel.org/doc/html/latest/core-api/index.html#core-utilities
instead, so I started a new file there.

I also considered adding the documentation inline in the
include/linux/timekeeping.h header, but couldn't figure out how to do
that in a way that would result both in helpful inline comments as
well as readable html output, so I settled for the latter, with
a small note pointing to it from the header.

Cc: Dave Chinner <david@fromorbit.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Stephen Boyd <sboyd@kernel.org>
Tested-by: Randy Dunlap <rdunlap@infradead.org>
Reviewed-by: Randy Dunlap <rdunlap@infradead.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

doc: document scope NOFS, NOIO APIs

Although the api is documented in the source code Ted has pointed out
that there is no mention in the core-api Documentation and there are
people looking there to find answers how to use a specific API.

Requested-by: "Theodore Y. Ts'o" <tytso@mit.edu>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

docs: core-api: add circular-buffers documentation

The circular-buffers.txt is already in ReST format. So, move it to the
core-api guide, where it belongs.

Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

docs: core-api: add cachetlb documentation

The cachetlb.txt is already in ReST format. So, move it to the
core-api guide, where it belongs.

Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

idr: Add documentation

Move the idr kernel-doc to its own idr.rst file and add a few
paragraphs about how to use it. Also add some more kernel-doc.

Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>

errseq: Add to documentation tree

- Move errseq.rst into core-api
- Add errseq to the core-api index
- Promote the header to a more prominent header type, otherwise we get three
entries in the table of contents.
- Reformat the table to look nicer and be a little more proportional in
terms of horizontal width per bit (the SF bit is still disproportionately
large, but there's no way to fix that).
- Include errseq kernel-doc in the errseq.rst
- Neaten some kernel-doc markup

Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>
Reviewed-by: Jeff Layton <jlayton@redhat.com>
Reviewed-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

doc: convert printk-formats.txt to rst

Documentation/printk-formats.txt is a candidate for conversion to
ReStructuredText format. Some effort has already been made to do this
conversion even thought the suffix is currently .txt

Changes required to complete conversion

- Move printk-formats.txt to core-api/printk-formats.rst
- Add entry to Documentation/core-api/index.rst
- Remove entry from Documentation/00-INDEX
- Fix minor grammatical errors.
- Order heading adornments as suggested by rst docs.
- Use 'Passed by reference' uniformly.
- Update pointer documentation around %px specifier.
- Fix erroneous double backticks (to commas).
- Remove extraneous double backticks (suggested by Jonathan Corbet).
- Simplify documentation for kobject.

Signed-off-by: Tobin C. Harding <me@tobin.cc>
[jc: downcased "kernel"]
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

docs: refcount_t documentation

Some functions from refcount_t API provide different
memory ordering guarantees that their atomic counterparts.
This adds a document outlining these differences (
Documentation/core-api/refcount-vs-atomic.rst) as well as
some other minor improvements.

Signed-off-by: Elena Reshetova <elena.reshetova@intel.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

doc: Add documentation for the genalloc subsystem

Genalloc/genpool has kerneldoc comments, but nothing has ever been pulled
into the docs themselves. Here's a first attempt, repurposed from an
article I wrote at https://lwn.net/Articles/729653/.

Signed-off-by: Jonathan Corbet <corbet@lwn.net>

docs-rst: convert librs book to ReST

Use pandoc to convert documentation to ReST by calling
Documentation/sphinx/tmplcvt script.

Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

kernel-api.tmpl: convert it to ReST

Brainless conversion of genericirq.tmpl book to ReST, via
Documentation/sphinx/tmplcvt

Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

genericirq.tmpl: convert it to ReST

Brainless conversion of genericirq.tmpl book to ReST, via
Documentation/sphinx/tmplcvt

Copyright information inserted manually.

Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

Documentation: Add flexible-arrays.rst to the documentation tree

Add flexible-arrays.rst to Documentation/core-api. Add kernel-doc
comments to allow referencing.

Signed-off-by: sayli karnik <karniksayli1995@gmail.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

Documentation: Update CPU hotplug and move it to core-api

The current CPU hotplug is outdated. During the update to what we
currently have I rewrote it partly and moved to sphinx format.

Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Mauro Carvalho Chehab <mchehab@kernel.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com>
Cc: Ashok Raj <ashok.raj@intel.com>
Cc: Joel Schopp <jschopp@austin.ibm.com>
Cc: linux-doc@vger.kernel.org
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

Documentation/atomic_ops.txt: convert to ReST markup

... and move to core-api folder.

Signed-off-by: Silvio Fricke <silvio.fricke@gmail.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

Documentation/local_ops.txt: convert to ReST markup

... and move to core-api folder.

Signed-off-by: Silvio Fricke <silvio.fricke@gmail.com>
Reviewed-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

Documentation/assoc_array.txt: convert to ReST markup

... and move to Documentation/core-api folder.

Signed-off-by: Silvio Fricke <silvio.fricke@gmail.com>
Reviewed-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

doc: Sphinxify the tracepoint docbook

Convert the tracepoint docbook template to RST and add it to the core-api
manual. No changes to the actual text beyond the mechanical formatting
conversion.

Cc: Jason Baron <jbaron@redhat.com>
Cc: William Cohen <wcohen@redhat.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

doc: Convert the debugobjects DocBook template to sphinx

A couple of the most minor heading tweaks, otherwise no changes to the text
itself beyond the mechanical conversion.

Note that the inclusion of the kerneldoc comments from the source has never
worked, since exported symbols were asked for and none of those functions
are exported to modules. It doesn't work here either :)

Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

Documentation/workqueue.txt: convert to ReST markup

... and move to Documentation/core-api folder.

Signed-off-by: Silvio Fricke <silvio.fricke@gmail.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

Documentation/00-index: update for new core-api folder

Signed-off-by: Silvio Fricke <silvio.fricke@gmail.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>