diff --git a/Documentation/conf.py b/Documentation/conf.py index 78dd6d1e7b88..b50c85083149 100644 --- 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. diff --git a/Documentation/asm-annotations.rst b/Documentation/core-api/asm-annotations.rst similarity index 97% rename from Documentation/asm-annotations.rst rename to Documentation/core-api/asm-annotations.rst index a64f2ca469d4..bc514ed59887 100644 --- a/Documentation/asm-annotations.rst +++ b/Documentation/core-api/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 ` +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 -`. +stack traces which are in turn necessary for kernel live patching +(Documentation/livepatch/livepatch.rst). Caveat and Discussion --------------------- diff --git a/Documentation/core-api/index.rst b/Documentation/core-api/index.rst index dc95df462eea..b0e7b4771fff 100644 --- 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 ============================= diff --git a/Documentation/core-api/wrappers/atomic_bitops.rst b/Documentation/core-api/wrappers/atomic_bitops.rst new file mode 100644 index 000000000000..bf24e4081a8f --- /dev/null +++ b/Documentation/core-api/wrappers/atomic_bitops.rst @@ -0,0 +1,18 @@ +.. 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 diff --git a/Documentation/core-api/wrappers/atomic_t.rst b/Documentation/core-api/wrappers/atomic_t.rst new file mode 100644 index 000000000000..ed109a964c77 --- /dev/null +++ b/Documentation/core-api/wrappers/atomic_t.rst @@ -0,0 +1,19 @@ +.. 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 + diff --git a/Documentation/core-api/wrappers/memory-barriers.rst b/Documentation/core-api/wrappers/memory-barriers.rst new file mode 100644 index 000000000000..532460b5e3eb --- /dev/null +++ b/Documentation/core-api/wrappers/memory-barriers.rst @@ -0,0 +1,18 @@ +.. 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 diff --git a/Documentation/doc-guide/sphinx.rst b/Documentation/doc-guide/sphinx.rst index 1228b85f6f77..c708cec889af 100644 --- 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 ===================== diff --git a/Documentation/driver-api/driver-model/devres.rst b/Documentation/driver-api/driver-model/devres.rst index 6f190967ba2e..dc1b2353cea3 100644 --- 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() diff --git a/Documentation/index.rst b/Documentation/index.rst index 4737c18c97ff..85eab6e990ab 100644 --- a/Documentation/index.rst +++ b/Documentation/index.rst @@ -1,11 +1,5 @@ .. 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 @@ -18,26 +12,72 @@ 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. +The essential guides for interacting with the kernel's development +community and getting your work upstream. + +.. toctree:: + :maxdepth: 1 + + process/development-process + process/submitting-patches + Code of conduct + maintainer/index + All development-process docs + + +Internal API manuals +-------------------- + +Manuals for use by developers working to interface with the rest of the +kernel. + +.. toctree:: + :maxdepth: 1 + + core-api/index + driver-api/index + subsystem-apis + Locking in the kernel + +Development tools and processes +------------------------------- + +Various other manuals with useful information for all kernel developers. + +.. toctree:: + :maxdepth: 1 + + process/license-rules + doc-guide/index + dev-tools/index + dev-tools/testing-overview + kernel-hacking/index + trace/index + fault-injection/index + livepatch/index -* :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. +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 admin-guide/index - kbuild/index + The kernel build system + admin-guide/reporting-issues.rst + User-space tools + userspace-api/index + +See also: the `Linux man pages `_, +which are kept separately from the kernel's own documentation. Firmware-related documentation ------------------------------ @@ -45,106 +85,11 @@ The following holds information on the kernel's expectations regarding the platform firmwares. .. toctree:: - :maxdepth: 2 + :maxdepth: 1 firmware-guide/index devicetree/index -Application-developer documentation ------------------------------------ - -The user-space API manual gathers together documents describing aspects of -the kernel interface as seen by application developers. - -.. toctree:: - :maxdepth: 2 - - userspace-api/index - - -Introduction to kernel development ----------------------------------- - -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. - -.. toctree:: - :maxdepth: 2 - - process/index - dev-tools/index - doc-guide/index - kernel-hacking/index - trace/index - maintainer/index - fault-injection/index - livepatch/index - - -Kernel API 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). - -.. toctree:: - :maxdepth: 2 - - 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 ------------------------------------ - -.. toctree:: - :maxdepth: 2 - - 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 diff --git a/Documentation/mm/unevictable-lru.rst b/Documentation/mm/unevictable-lru.rst index b280367d6a44..4a0e158aa9ce 100644 --- 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 diff --git a/Documentation/process/5.Posting.rst b/Documentation/process/5.Posting.rst index 906235c11c24..d87f1fee4cbc 100644 --- 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 diff --git a/Documentation/process/code-of-conduct-interpretation.rst b/Documentation/process/code-of-conduct-interpretation.rst index 4f8a06b00f60..922e0b547bc3 100644 --- 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. diff --git a/Documentation/process/coding-style.rst b/Documentation/process/coding-style.rst index 03eb53fd029a..007e49ef6cec 100644 --- 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 ---------------------- diff --git a/Documentation/process/index.rst b/Documentation/process/index.rst index 2ba2a1582bbe..d4b6217472b0 100644 --- a/Documentation/process/index.rst +++ b/Documentation/process/index.rst @@ -5,6 +5,7 @@ .. _process_index: +============================================= Working with the kernel development community ============================================= diff --git a/Documentation/staging/index.rst b/Documentation/staging/index.rst index abd0d18254d2..ded8254bc0d7 100644 --- 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 diff --git a/Documentation/subsystem-apis.rst b/Documentation/subsystem-apis.rst new file mode 100644 index 000000000000..af65004a80aa --- /dev/null +++ b/Documentation/subsystem-apis.rst @@ -0,0 +1,58 @@ +.. 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 diff --git a/Documentation/trace/kprobes.rst b/Documentation/trace/kprobes.rst index f318bceda1e6..48cf778a2468 100644 --- 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 diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl index 79e759aac543..4aa09e0cb86a 100755 --- 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