Merge branch 'docs-mw' into docs-next

05fff6ba · Jonathan Corbet · 3ef859a4 · 69d517e6 · 05fff6ba · 05fff6ba
Commit 05fff6ba authored Sep 29, 2022 by Jonathan Corbet
18 changed files
--- a/Documentation/conf.py
+++ b/Documentation/conf.py
@@ -370,7 +370,8 @@ html_static_path = ['sphinx-static']
 html_use_smartypants = False

 # Custom sidebar templates, maps document names to template names.
-#html_sidebars = {}
+# Note that the RTD theme ignores this.
+html_sidebars = { '**': ['searchbox.html', 'localtoc.html', 'sourcelink.html']}

 # Additional templates that should be rendered to pages, maps page names to
 # template names.

--- a/Documentation/asm-annotations.rst
+++ b/Documentation/asm-annotations.rst
@@ -43,10 +43,11 @@ annotated objects like this, tools can be run on them to generate more useful
 information. In particular, on properly annotated objects, ``objtool`` can be
 run to check and fix the object if needed. Currently, ``objtool`` can report
 missing frame pointer setup/destruction in functions. It can also
-automatically generate annotations for :doc:`ORC unwinder <x86/orc-unwinder>`
+automatically generate annotations for the ORC unwinder
+(Documentation/x86/orc-unwinder.rst)
 for most code. Both of these are especially important to support reliable
-stack traces which are in turn necessary for :doc:`Kernel live patching
-<livepatch/livepatch>`.
+stack traces which are in turn necessary for kernel live patching
+(Documentation/livepatch/livepatch.rst).

 Caveat and Discussion
 ---------------------

--- a/Documentation/core-api/index.rst
+++ b/Documentation/core-api/index.rst
@@ -23,6 +23,7 @@ it.
   printk-formats
   printk-index
   symbol-namespaces
+   asm-annotations

 Data structures and low-level utilities
 =======================================
@@ -44,6 +45,8 @@ Library functionality that is used throughout the kernel.
   this_cpu_ops
   timekeeping
   errseq
+   wrappers/atomic_t
+   wrappers/atomic_bitops

 Low level entry and exit
 ========================
@@ -67,6 +70,7 @@ Documentation/locking/index.rst for more related documentation.
   local_ops
   padata
   ../RCU/index
+   wrappers/memory-barriers.rst

 Low-level hardware management
 =============================

--- a/Documentation/core-api/wrappers/atomic_bitops.rst
+++ b/Documentation/core-api/wrappers/atomic_bitops.rst
+.. SPDX-License-Identifier: GPL-2.0
+   This is a simple wrapper to bring atomic_bitops.txt into the RST world
+   until such a time as that file can be converted directly.
+
+=============
+Atomic bitops
+=============
+
+.. raw:: latex
+
+    \footnotesize
+
+.. include:: ../../atomic_bitops.txt
+   :literal:
+
+.. raw:: latex
+
+    \normalsize
--- a/Documentation/core-api/wrappers/atomic_t.rst
+++ b/Documentation/core-api/wrappers/atomic_t.rst
+.. SPDX-License-Identifier: GPL-2.0
+   This is a simple wrapper to bring atomic_t.txt into the RST world
+   until such a time as that file can be converted directly.
+
+============
+Atomic types
+============
+
+.. raw:: latex
+
+    \footnotesize
+
+.. include:: ../../atomic_t.txt
+   :literal:
+
+.. raw:: latex
+
+    \normalsize
+
--- a/Documentation/core-api/wrappers/memory-barriers.rst
+++ b/Documentation/core-api/wrappers/memory-barriers.rst
+.. SPDX-License-Identifier: GPL-2.0
+   This is a simple wrapper to bring memory-barriers.txt into the RST world
+   until such a time as that file can be converted directly.
+
+============================
+Linux kernel memory barriers
+============================
+
+.. raw:: latex
+
+    \footnotesize
+
+.. include:: ../../memory-barriers.txt
+   :literal:
+
+.. raw:: latex
+
+    \normalsize
--- a/Documentation/doc-guide/sphinx.rst
+++ b/Documentation/doc-guide/sphinx.rst
@@ -48,10 +48,6 @@ or ``virtualenv``, depending on how your distribution packaged Python 3.
      on the Sphinx version, it should be installed separately,
      with ``pip install sphinx_rtd_theme``.

-   #) Some ReST pages contain math expressions. Due to the way Sphinx works,
-      those expressions are written using LaTeX notation. It needs texlive
-      installed with amsfonts and amsmath in order to evaluate them.
-
 In summary, if you want to install Sphinx version 2.4.4, you should do::

       $ virtualenv sphinx_2.4.4
@@ -86,6 +82,27 @@ Depending on the distribution, you may also need to install a series of
 ``texlive`` packages that provide the minimal set of functionalities
 required for ``XeLaTeX`` to work.

+Math Expressions in HTML
+------------------------
+
+Some ReST pages contain math expressions. Due to the way Sphinx works,
+those expressions are written using LaTeX notation.
+There are two options for Sphinx to render math expressions in html output.
+One is an extension called `imgmath`_ which converts math expressions into
+images and embeds them in html pages.
+The other is an extension called `mathjax`_ which delegates math rendering
+to JavaScript capable web browsers.
+The former was the only option for pre-6.1 kernel documentation and it
+requires quite a few texlive packages including amsfonts and amsmath among
+others.
+
+Since kernel release 6.1, html pages with math expressions can be built
+without installing any texlive packages. See `Choice of Math Renderer`_ for
+further info.
+
+.. _imgmath: https://www.sphinx-doc.org/en/master/usage/extensions/math.html#module-sphinx.ext.imgmath
+.. _mathjax: https://www.sphinx-doc.org/en/master/usage/extensions/math.html#module-sphinx.ext.mathjax
+
 .. _sphinx-pre-install:

 Checking for Sphinx dependencies
@@ -164,6 +181,38 @@ To remove the generated documentation, run ``make cleandocs``.
 	  as well would improve the quality of images embedded in PDF
 	  documents, especially for kernel releases 5.18 and later.

+Choice of Math Renderer
+-----------------------
+
+Since kernel release 6.1, mathjax works as a fallback math renderer for
+html output.\ [#sph1_8]_
+
+Math renderer is chosen depending on available commands as shown below:
+
+.. table:: Math Renderer Choices for HTML
+
+    ============= ================= ============
+    Math renderer Required commands Image format
+    ============= ================= ============
+    imgmath       latex, dvipng     PNG (raster)
+    mathjax
+    ============= ================= ============
+
+The choice can be overridden by setting an environment variable
+``SPHINX_IMGMATH`` as shown below:
+
+.. table:: Effect of Setting ``SPHINX_IMGMATH``
+
+    ====================== ========
+    Setting                Renderer
+    ====================== ========
+    ``SPHINX_IMGMATH=yes`` imgmath
+    ``SPHINX_IMGMATH=no``  mathjax
+    ====================== ========
+
+.. [#sph1_8] Fallback of math renderer requires Sphinx >=1.8.
+
+
 Writing Documentation
 =====================


--- a/Documentation/driver-api/driver-model/devres.rst
+++ b/Documentation/driver-api/driver-model/devres.rst
@@ -301,6 +301,7 @@ IO region
  devm_release_region()
  devm_release_resource()
  devm_request_mem_region()
+  devm_request_free_mem_region()
  devm_request_region()
  devm_request_resource()

@@ -334,7 +335,7 @@ IRQ
  devm_irq_alloc_descs_from()
  devm_irq_alloc_generic_chip()
  devm_irq_setup_generic_chip()
-  devm_irq_sim_init()
+  devm_irq_domain_create_sim()

 LED
  devm_led_classdev_register()

--- a/Documentation/index.rst
+++ b/Documentation/index.rst
 .. SPDX-License-Identifier: GPL-2.0

-
-.. The Linux Kernel documentation master file, created by
-   sphinx-quickstart on Fri Feb 12 13:51:46 2016.
-   You can adapt this file completely to your liking, but it should at least
-   contain the root `toctree` directive.
-
 .. _linux_doc:

 The Linux Kernel documentation
@@ -18,133 +12,84 @@ documents into a coherent whole.  Please note that improvements to the
 documentation are welcome; join the linux-doc list at vger.kernel.org if
 you want to help out.

-Licensing documentation
-----------------------
+Working with the development community
+--------------------------------------

-The following describes the license of the Linux kernel source code
-(GPLv2), how to properly mark the license of individual files in the source
-tree, as well as links to the full license text.
-
-* :ref:`kernel_licensing`
-
-User-oriented documentation
---------------------------
-
-The following manuals are written for *users* of the kernel — those who are
-trying to get it to work optimally on a given system.
+The essential guides for interacting with the kernel's development
+community and getting your work upstream.

 .. toctree::
-   :maxdepth: 2
-
-   admin-guide/index
-   kbuild/index
-
-Firmware-related documentation
------------------------------
-The following holds information on the kernel's expectations regarding the
-platform firmwares.
+   :maxdepth: 1

-.. toctree::
-   :maxdepth: 2
+   process/development-process
+   process/submitting-patches
+   Code of conduct <process/code-of-conduct>
+   maintainer/index
+   All development-process docs <process/index>

-   firmware-guide/index
-   devicetree/index

-Application-developer documentation
-----------------------------------
+Internal API manuals
+--------------------

-The user-space API manual gathers together documents describing aspects of
-the kernel interface as seen by application developers.
+Manuals for use by developers working to interface with the rest of the
+kernel.

 .. toctree::
-   :maxdepth: 2
-
-   userspace-api/index
+   :maxdepth: 1

+   core-api/index
+   driver-api/index
+   subsystem-apis
+   Locking in the kernel <locking/index>

-Introduction to kernel development
----------------------------------
+Development tools and processes
+-------------------------------

-These manuals contain overall information about how to develop the kernel.
-The kernel community is quite large, with thousands of developers
-contributing over the course of a year.  As with any large community,
-knowing how things are done will make the process of getting your changes
-merged much easier.
+Various other manuals with useful information for all kernel developers.

 .. toctree::
-   :maxdepth: 2
+   :maxdepth: 1

-   process/index
-   dev-tools/index
+   process/license-rules
   doc-guide/index
+   dev-tools/index
+   dev-tools/testing-overview
   kernel-hacking/index
   trace/index
-   maintainer/index
   fault-injection/index
   livepatch/index


-Kernel API documentation
------------------------
+User-oriented documentation
+---------------------------

-These books get into the details of how specific kernel subsystems work
-from the point of view of a kernel developer.  Much of the information here
-is taken directly from the kernel source, with supplemental material added
-as needed (or at least as we managed to add it — probably *not* all that is
-needed).
+The following manuals are written for *users* of the kernel — those who are
+trying to get it to work optimally on a given system and application
+developers seeking information on the kernel's user-space APIs.

 .. toctree::
-   :maxdepth: 2
+   :maxdepth: 1

-   driver-api/index
-   core-api/index
-   locking/index
-   accounting/index
-   block/index
-   cdrom/index
-   cpu-freq/index
-   fb/index
-   fpga/index
-   hid/index
-   i2c/index
-   iio/index
-   isdn/index
-   infiniband/index
-   leds/index
-   netlabel/index
-   networking/index
-   pcmcia/index
-   power/index
-   target/index
-   timers/index
-   spi/index
-   w1/index
-   watchdog/index
-   virt/index
-   input/index
-   hwmon/index
-   gpu/index
-   security/index
-   sound/index
-   crypto/index
-   filesystems/index
-   mm/index
-   bpf/index
-   usb/index
-   PCI/index
-   scsi/index
-   misc-devices/index
-   scheduler/index
-   mhi/index
-   peci/index
-
-Architecture-agnostic documentation
-----------------------------------
+   admin-guide/index
+   The kernel build system <kbuild/index>
+   admin-guide/reporting-issues.rst
+   User-space tools <tools/index>
+   userspace-api/index
+
+See also: the `Linux man pages <https://www.kernel.org/doc/man-pages/>`_,
+which are kept separately from the kernel's own documentation.
+
+Firmware-related documentation
+------------------------------
+The following holds information on the kernel's expectations regarding the
+platform firmwares.

 .. toctree::
-   :maxdepth: 2
+   :maxdepth: 1
+
+   firmware-guide/index
+   devicetree/index

-   asm-annotations

 Architecture-specific documentation
 -----------------------------------
@@ -163,9 +108,8 @@ of the documentation body, or may require some adjustments and/or conversion
 to ReStructured Text format, or are simply too old.

 .. toctree::
-   :maxdepth: 2
+   :maxdepth: 1

-   tools/index
   staging/index



--- a/Documentation/mm/unevictable-lru.rst
+++ b/Documentation/mm/unevictable-lru.rst
@@ -197,7 +197,7 @@ unevictable list for the memory cgroup and node being scanned.
 There may be situations where a page is mapped into a VM_LOCKED VMA, but the
 page is not marked as PG_mlocked.  Such pages will make it all the way to
 shrink_active_list() or shrink_page_list() where they will be detected when
-vmscan walks the reverse map in page_referenced() or try_to_unmap().  The page
+vmscan walks the reverse map in folio_referenced() or try_to_unmap().  The page
 is culled to the unevictable list when it is released by the shrinker.

 To "cull" an unevictable page, vmscan simply puts the page back on the LRU list
@@ -267,7 +267,7 @@ the LRU.  Such pages can be "noticed" by memory management in several places:
 (4) in the fault path and when a VM_LOCKED stack segment is expanded; or

 (5) as mentioned above, in vmscan:shrink_page_list() when attempting to
-     reclaim a page in a VM_LOCKED VMA by page_referenced() or try_to_unmap().
+     reclaim a page in a VM_LOCKED VMA by folio_referenced() or try_to_unmap().

 mlocked pages become unlocked and rescued from the unevictable list when:

@@ -547,7 +547,7 @@ vmscan's shrink_inactive_list() and shrink_page_list() also divert obviously
 unevictable pages found on the inactive lists to the appropriate memory cgroup
 and node unevictable list.

-rmap's page_referenced_one(), called via vmscan's shrink_active_list() or
+rmap's folio_referenced_one(), called via vmscan's shrink_active_list() or
 shrink_page_list(), and rmap's try_to_unmap_one() called via shrink_page_list(),
 check for (3) pages still mapped into VM_LOCKED VMAs, and call mlock_vma_page()
 to correct them.  Such pages are culled to the unevictable list when released

--- a/Documentation/process/5.Posting.rst
+++ b/Documentation/process/5.Posting.rst
@@ -256,8 +256,10 @@ The tags in common use are:
 - Cc: the named person received a copy of the patch and had the
   opportunity to comment on it.

-Be careful in the addition of tags to your patches: only Cc: is appropriate
-for addition without the explicit permission of the person named.
+Be careful in the addition of tags to your patches, as only Cc: is appropriate
+for addition without the explicit permission of the person named; using
+Reported-by: is fine most of the time as well, but ask for permission if
+the bug was reported in private.


 Sending the patch

--- a/Documentation/process/code-of-conduct-interpretation.rst
+++ b/Documentation/process/code-of-conduct-interpretation.rst
@@ -127,10 +127,12 @@ are listed at https://kernel.org/code-of-conduct.html.  Members can not
 access reports made before they joined or after they have left the
 committee.

-The initial Code of Conduct Committee consists of volunteer members of
-the TAB, as well as a professional mediator acting as a neutral third
-party.  The first task of the committee is to establish documented
-processes, which will be made public.
+The Code of Conduct Committee consists of volunteer community members
+appointed by the TAB, as well as a professional mediator acting as a
+neutral third party.  The processes the Code of Conduct committee will
+use to address reports is varied and will depend on the individual
+circumstance, however, this file serves as documentation for the
+general process used.

 Any member of the committee, including the mediator, can be contacted
 directly if a reporter does not wish to include the full committee in a
@@ -141,16 +143,16 @@ processes (see above) and consults with the TAB as needed and
 appropriate, for instance to request and receive information about the
 kernel community.

-Any decisions by the committee will be brought to the TAB, for
-implementation of enforcement with the relevant maintainers if needed.
-A decision by the Code of Conduct Committee can be overturned by the TAB
-by a two-thirds vote.
+Any decisions regarding enforcement recommendations will be brought to
+the TAB for implementation of enforcement with the relevant maintainers
+if needed.  A decision by the Code of Conduct Committee can be overturned
+by the TAB by a two-thirds vote.

 At quarterly intervals, the Code of Conduct Committee and TAB will
 provide a report summarizing the anonymised reports that the Code of
 Conduct committee has received and their status, as well details of any
 overridden decisions including complete and identifiable voting details.

-We expect to establish a different process for Code of Conduct Committee
-staffing beyond the bootstrap period.  This document will be updated
-with that information when this occurs.
+Because how we interpret and enforce the Code of Conduct will evolve over
+time, this document will be updated when necessary to reflect any
+changes.
--- a/Documentation/process/coding-style.rst
+++ b/Documentation/process/coding-style.rst
@@ -1186,6 +1186,68 @@ expression used.  For instance:
 	#endif /* CONFIG_SOMETHING */


+22) Do not crash the kernel
+---------------------------
+
+In general, the decision to crash the kernel belongs to the user, rather
+than to the kernel developer.
+
+Avoid panic()
+*************
+
+panic() should be used with care and primarily only during system boot.
+panic() is, for example, acceptable when running out of memory during boot and
+not being able to continue.
+
+Use WARN() rather than BUG()
+****************************
+
+Do not add new code that uses any of the BUG() variants, such as BUG(),
+BUG_ON(), or VM_BUG_ON(). Instead, use a WARN*() variant, preferably
+WARN_ON_ONCE(), and possibly with recovery code. Recovery code is not
+required if there is no reasonable way to at least partially recover.
+
+"I'm too lazy to do error handling" is not an excuse for using BUG(). Major
+internal corruptions with no way of continuing may still use BUG(), but need
+good justification.
+
+Use WARN_ON_ONCE() rather than WARN() or WARN_ON()
+**************************************************
+
+WARN_ON_ONCE() is generally preferred over WARN() or WARN_ON(), because it
+is common for a given warning condition, if it occurs at all, to occur
+multiple times. This can fill up and wrap the kernel log, and can even slow
+the system enough that the excessive logging turns into its own, additional
+problem.
+
+Do not WARN lightly
+*******************
+
+WARN*() is intended for unexpected, this-should-never-happen situations.
+WARN*() macros are not to be used for anything that is expected to happen
+during normal operation. These are not pre- or post-condition asserts, for
+example. Again: WARN*() must not be used for a condition that is expected
+to trigger easily, for example, by user space actions. pr_warn_once() is a
+possible alternative, if you need to notify the user of a problem.
+
+Do not worry about panic_on_warn users
+**************************************
+
+A few more words about panic_on_warn: Remember that ``panic_on_warn`` is an
+available kernel option, and that many users set this option. This is why
+there is a "Do not WARN lightly" writeup, above. However, the existence of
+panic_on_warn users is not a valid reason to avoid the judicious use
+WARN*(). That is because, whoever enables panic_on_warn has explicitly
+asked the kernel to crash if a WARN*() fires, and such users must be
+prepared to deal with the consequences of a system that is somewhat more
+likely to crash.
+
+Use BUILD_BUG_ON() for compile-time assertions
+**********************************************
+
+The use of BUILD_BUG_ON() is acceptable and encouraged, because it is a
+compile-time assertion that has no effect at runtime.
+
 Appendix I) References
 ----------------------


--- a/Documentation/process/index.rst
+++ b/Documentation/process/index.rst
@@ -5,6 +5,7 @@

 .. _process_index:

+=============================================
 Working with the kernel development community
 =============================================


--- a/Documentation/staging/index.rst
+++ b/Documentation/staging/index.rst
@@ -14,45 +14,3 @@ Unsorted Documentation
   static-keys
   tee
   xz
-
-Atomic Types
-============
-
-.. raw:: latex
-
-    \footnotesize
-
-.. include:: ../atomic_t.txt
-   :literal:
-
-.. raw:: latex
-
-    \normalsize
-
-Atomic bitops
-=============
-
-.. raw:: latex
-
-    \footnotesize
-
-.. include:: ../atomic_bitops.txt
-   :literal:
-
-.. raw:: latex
-
-    \normalsize
-
-Memory Barriers
-===============
-
-.. raw:: latex
-
-    \footnotesize
-
-.. include:: ../memory-barriers.txt
-   :literal:
-
-.. raw:: latex
-
-    \normalsize
--- a/Documentation/subsystem-apis.rst
+++ b/Documentation/subsystem-apis.rst
+.. SPDX-License-Identifier: GPL-2.0
+
+==============================
+Kernel subsystem documentation
+==============================
+
+These books get into the details of how specific kernel subsystems work
+from the point of view of a kernel developer.  Much of the information here
+is taken directly from the kernel source, with supplemental material added
+as needed (or at least as we managed to add it — probably *not* all that is
+needed).
+
+**Fixme**: much more organizational work is needed here.
+
+.. toctree::
+   :maxdepth: 1
+
+   driver-api/index
+   core-api/index
+   locking/index
+   accounting/index
+   block/index
+   cdrom/index
+   cpu-freq/index
+   fb/index
+   fpga/index
+   hid/index
+   i2c/index
+   iio/index
+   isdn/index
+   infiniband/index
+   leds/index
+   netlabel/index
+   networking/index
+   pcmcia/index
+   power/index
+   target/index
+   timers/index
+   spi/index
+   w1/index
+   watchdog/index
+   virt/index
+   input/index
+   hwmon/index
+   gpu/index
+   security/index
+   sound/index
+   crypto/index
+   filesystems/index
+   mm/index
+   bpf/index
+   usb/index
+   PCI/index
+   scsi/index
+   misc-devices/index
+   scheduler/index
+   mhi/index
+   peci/index
--- a/Documentation/trace/kprobes.rst
+++ b/Documentation/trace/kprobes.rst
@@ -328,8 +328,8 @@ Configuring Kprobes
 ===================

 When configuring the kernel using make menuconfig/xconfig/oldconfig,
-ensure that CONFIG_KPROBES is set to "y". Under "General setup", look
-for "Kprobes".
+ensure that CONFIG_KPROBES is set to "y", look for "Kprobes" under
+"General architecture-dependent options".

 So that you can load and unload Kprobes-based instrumentation modules,
 make sure "Loadable module support" (CONFIG_MODULES) and "Module

--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -3751,7 +3751,7 @@ sub process {
 		if ($realfile =~ /\.S$/ &&
 		    $line =~ /^\+\s*(?:[A-Z]+_)?SYM_[A-Z]+_(?:START|END)(?:_[A-Z_]+)?\s*\(\s*\.L/) {
 			WARN("AVOID_L_PREFIX",
-			     "Avoid using '.L' prefixed local symbol names for denoting a range of code via 'SYM_*_START/END' annotations; see Documentation/asm-annotations.rst\n" . $herecurr);
+			     "Avoid using '.L' prefixed local symbol names for denoting a range of code via 'SYM_*_START/END' annotations; see Documentation/core-api/asm-annotations.rst\n" . $herecurr);
 		}

 # check we are in a valid source file C or perl if not then ignore this hunk
@@ -4695,12 +4695,12 @@ sub process {
 			}
 		}

-# avoid BUG() or BUG_ON()
-		if ($line =~ /\b(?:BUG|BUG_ON)\b/) {
+# do not use BUG() or variants
+		if ($line =~ /\b(?!AA_|BUILD_|DCCP_|IDA_|KVM_|RWLOCK_|snd_|SPIN_)(?:[a-zA-Z_]*_)?BUG(?:_ON)?(?:_[A-Z_]+)?\s*\(/) {
 			my $msg_level = \&WARN;
 			$msg_level = \&CHK if ($file);
 			&{$msg_level}("AVOID_BUG",
-				      "Avoid crashing the kernel - try using WARN_ON & recovery code rather than BUG() or BUG_ON()\n" . $herecurr);
+				      "Do not crash the kernel unless it is absolutely unavoidable--use WARN_ON_ONCE() plus recovery code (if feasible) instead of BUG() or variants\n" . $herecurr);
 		}

 # avoid LINUX_VERSION_CODE