Merge tag 'trace-v7.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Don't destroy user event fields when removal fails

   User event fields are destroyed before the event is removed from
   visibility. But that can fail leaving the still visible event with no
   fields. Move the destroying of the fields to after the event is
   successfully removed from visibility.

 - Initialize function graph state is fork before calling
   copy_exec_state()

   For non-CLONE_VM forks, copy_exec_state() allocates a new
   task_exec_state. If that allocation fails, ftrace_graph_exit_task()
   will free the tasks ret_stack pointer. Since that pointer is still
   using the parent's ret_stack, it mistakenly frees the parent's
   pointer too.

   Call ftrace_graph_init() on the task first which will NULL out the
   new tasks's ret_stack and if the copy fails, it will not free
   anything.

 - Remove FGRAPH_MAX_INDEX

   The macro FGRAPH_MAX_INDEX was added but never used. Remove it.

 - Save ent_size in function graph printing of nested functions

   The function graph tracer needs to look at the next event to see if
   the next event is the return of the current function entry. If it is,
   it prints a single line:

	ktime_get();

   Otherwise it prints it like a nested function:

	tick_nohz_irq_exit() {
	    ktime_get();
	    kcpustat_irq_exit();
	}

   In order to look at the next event, it must save the current event so
   that it has the information to print from it. It saves the event in
   the iterator descriptor called "ent". What it doesn't save is the
   ent_size of the event which is now used to know if the function graph
   arguments are to be printed. The peek doesn't save the size so the
   size used happens to be that of the size of the last event that was
   seen.

   Save the entry event size in the iterator descriptor so that the
   correct size is used.

 - Fix several errors with freeing data in the histogram code

   The histogram code had a lot of leaked or or incorrect accounting
   when failures happen. Correct them.

 - Fix histogram regression of .percent and .graph modifiers

   Up until 6.3 histogram values could have "percent" or "graph"
   modifiers that changed how they were printed. But a change that added
   restricting histograms values from being strings, stack traces and
   other modifiers inadvertently prevented them from using the percent
   and graph modifiers, which were legal use cases for values.

   Put back the percent and graph modifiers.

 - Fix various typos in the comments

 - Set the trace_clock before initializing a histogram with clock
   argument

   The histogram API allows the user to specific which trace clock to
   use via a "clock=" string. The histogram is set up first before the
   clock is checked. If the passed in clock is not valid, it exits
   without fully fixing up the histogram leaving it on the list and a
   use-after-free can trigger.

   Update the clock argument first and if it fails then exit gracefully
   before the histogram trigger is placed on any lists.

 - Restore :mod: trailer after parsing in ftrace_set_clr_event

   The function ftrace_set_clr_event() modifies the parse string and
   needs to put it back to what was passed in. It searches for ":mod:"
   via a strsep() but fails to put back the first ':' in the string.

   Add back the ':' in the passed in string.

 - Take trace_array reference when opening a tracer options file

   The options files are dynamically created and some tracers add their
   own options. When a tracer adds their own list of options, the
   trace_array holding them has an array to hold the list of options for
   each tracer. This array increases in size via a krealloc(), and the
   new entry gets a newly allocated array to hold the options of the new
   tracer being added.

   The element in each entry of the tracer's option array holds a
   pointer back to the trace_array, a pointer to the tracer it is
   associated to, a pointer to the flags of the option.

   The issue is that these arrays are freed when the trace_array is
   freed when its instance it represents is removed from the instances
   directory. There's a race that an open of one of these options files
   can happen when the instance is being removed.

   Add a new helper function to be called by the open function of the
   options file to iterate all existing trace_arrays under a lock and
   find the one that has the given option element in one of it's tracer
   arrays. If found, then update the associated trace_array's reference
   counter to keep it from being freed. If not found, have the open call
   return -ENODEV.

 - Disable interrupts when acquiring the lock in rb_wake_up_waiters()

   The function rb_wake_up_waiters() assumes it will be called in
   interrupt context and does not disable irqs when taking
   cpu_buffer->reader_lock, which can be called in hard interrupt
   context. The issue is in PREEMPT_RT, this function is called in
   thread context leaving this lock open to a deadlock.

   Take the lock with interrupts disabled.

 - Use rcu_assign_pointer() for tmp_ops filter hash

   The tmp_ops used in update_ftrace_direct_mod() assigns its
   filter_hash field directly, but that field is annotated as __rcu and
   sparse complains. Assign it with rcu_assign_pointer()

 - Fix use-after-free in enable_trigger_private_data_free()

   The trace_event_call is accessed through the event_trigger_data's
   trace_event_file pointer to put the trace_event_call on freeing. The
   issue is that the trace_event_file data may have been freed already
   causing a use-after-free. Add a field to the event_trigger_data that
   points directly to the trace_event_call so that it can decrement its
   reference directly without needing to go through the
   trace_event_file.

 - Fix accounting of buffer data remote headers

   trace_buffer_desc_size() and trace_remote_alloc_buffer() undercount
   the number of pages is needed for the asked for size as it doesn't
   take into account the meta data on each page. Add a helper function
   to do the calculation properly and use that in these functions.

 - Catch nr_page_va overflow in ring_buffer_desc sizing

   The number of pages per remote ring buffer is capped by
   ring_buffer_desc::nr_page_va (32 bits). A buffer_size large enough to
   overflow that field would silently allocate a descriptor smaller than
   what was asked for.

 - Do not resize the subbuf order if any per_cpu buffer is disabled

   The mmapping of ring buffers disables resizing the subbuffers, but it
   is done per-cpu whereas the subbuf size change is done for all the
   per_cpu buffers under the buffer->mutex. It could change the size of
   some while the mapping is happening on others. Have the resize of the
   subbuf order check all the per_cpu buffers under the lock to see if
   any of them is disabled before starting and causing an inconsistency
   between buffers that are being mapped.

* tag 'trace-v7.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: (25 commits)
  ring-buffer: Check resize_disabled before publishing the new subbuf order
  tracing/remotes: Catch nr_page_va overflow in ring_buffer_desc sizing
  tracing/remotes: Account for ring buffer page header in size calculation
  tracing: Don't dereference trace_event_file in deferred trigger free
  ftrace: Use rcu_assign_pointer() for tmp_ops filter hash
  ring-buffer: Acquire the lock with irqsave in rb_wake_up_waiters()
  tracing: Take trace_array reference when opening a tracer options file
  tracing: Fix ring_buffer_read_page_size() kernel-doc
  tracing: Restore :mod: trailer after parsing in ftrace_set_clr_event()
  tracing: Fix memory corruption from a "STACKTRACE" histogram key
  tracing: Fix memory corruption from the histogram stacktrace modifier
  tracing: Undo the registration when enabling the histogram trigger fails
  tracing: Take the reference before publishing the named histogram trigger
  tracing: Set the trace clock before registering the histogram trigger
  tracing: Fix typo "preceeded" in comment
  tracing: Fix typo "availabe" in comment
  tracing: Let histogram values keep the percent and graph modifiers
  tracing: Keep the entry count when the histogram stats allocation fails
  tracing: Free histogram the field rejected for a bad modifier
  tracing: Free histogram the var ref when its initialization fails
  ...

1 files changed, 617 insertions, 0 deletions

diff --git a/Documentation/conf.py b/Documentation/conf.py
new file mode 100644
index 000000000..5ab26ce89
--- /dev/null
+++ b/Documentation/conf.py
@@ -0,0 +1,617 @@
+# SPDX-License-Identifier: GPL-2.0-only
+# pylint: disable=C0103,C0209
+
+"""
+The Linux Kernel documentation build configuration file.
+"""
+
+import os
+import shutil
+import sys
+
+from  textwrap import dedent
+
+import sphinx
+
+# Location of Documentation/ directory
+kern_doc_dir = os.path.dirname(os.path.abspath(__file__))
+
+# Add location of Sphinx extensions
+sys.path.insert(0, os.path.join(kern_doc_dir, "sphinx"))
+
+# Allow sphinx.ext.autodoc to document files at tools and scripts
+sys.path.append(os.path.join(kern_doc_dir, "..", "tools"))
+sys.path.append(os.path.join(kern_doc_dir, "..", "scripts"))
+
+# Minimal supported version
+needs_sphinx = "3.4.3"
+
+# Get Sphinx version
+major, minor, patch = sphinx.version_info[:3]          # pylint: disable=I1101
+
+# Include_patterns were added on Sphinx 5.1
+if (major < 5) or (major == 5 and minor < 1):
+    has_include_patterns = False
+else:
+    has_include_patterns = True
+    # Include patterns that don't contain directory names, in glob format
+    include_patterns = ["**.rst"]
+
+# Exclude of patterns that don't contain directory names, in glob format.
+exclude_patterns = []
+
+# List of patterns that contain directory names in glob format.
+dyn_include_patterns = []
+dyn_exclude_patterns = ["output", "sphinx-includes"]
+
+# Currently, only netlink/specs has a parser for yaml.
+# Prefer using include patterns if available, as it is faster
+if has_include_patterns:
+    dyn_include_patterns.append("netlink/specs/*.yaml")
+else:
+    dyn_exclude_patterns.append("netlink/*.yaml")
+    dyn_exclude_patterns.append("devicetree/bindings/**.yaml")
+    dyn_exclude_patterns.append("core-api/kho/bindings/**.yaml")
+
+# Link to man pages
+manpages_url = 'https://man7.org/linux/man-pages/man{section}/{page}.{section}.html'
+
+# Properly handle directory patterns and LaTeX docs
+# -------------------------------------------------
+
+def config_init(app, config):
+    """
+    Initialize path-dependent variables
+
+    On Sphinx, all directories are relative to what it is passed as
+    SOURCEDIR parameter for sphinx-build. Due to that, all patterns
+    that have directory names on it need to be dynamically set, after
+    converting them to a relative path.
+
+    As Sphinx doesn't include any patterns outside SOURCEDIR, we should
+    exclude relative patterns that start with "../".
+    """
+
+    # setup include_patterns dynamically
+    if has_include_patterns:
+        for p in dyn_include_patterns:
+            full = os.path.join(kern_doc_dir, p)
+
+            rel_path = os.path.relpath(full, start=app.srcdir)
+            if rel_path.startswith("../"):
+                continue
+
+            config.include_patterns.append(rel_path)
+
+    # setup exclude_patterns dynamically
+    for p in dyn_exclude_patterns:
+        full = os.path.join(kern_doc_dir, p)
+
+        rel_path = os.path.relpath(full, start=app.srcdir)
+        if rel_path.startswith("../"):
+            continue
+
+        config.exclude_patterns.append(rel_path)
+
+    # LaTeX and PDF output require a list of documents with are dependent
+    # of the app.srcdir. Add them here
+
+    # Handle the case where SPHINXDIRS is used
+    if not os.path.samefile(kern_doc_dir, app.srcdir):
+        # Add a tag to mark that the build is actually a subproject
+        tags.add("subproject")
+
+        # get index.rst, if it exists
+        doc = os.path.basename(app.srcdir)
+        fname = "index"
+        if os.path.exists(os.path.join(app.srcdir, fname + ".rst")):
+            latex_documents.append((fname, doc + ".tex",
+                                    "Linux %s Documentation" % doc.capitalize(),
+                                    "The kernel development community",
+                                    "manual"))
+            return
+
+    # When building all docs, or when a main index.rst doesn't exist, seek
+    # for it on subdirectories
+    for doc in os.listdir(app.srcdir):
+        fname = os.path.join(doc, "index")
+        if not os.path.exists(os.path.join(app.srcdir, fname + ".rst")):
+            continue
+
+        has = False
+        for l in latex_documents:
+            if l[0] == fname:
+                has = True
+                break
+
+        if not has:
+            latex_documents.append((fname, doc + ".tex",
+                                    "Linux %s Documentation" % doc.capitalize(),
+                                    "The kernel development community",
+                                    "manual"))
+
+# helper
+# ------
+
+
+def have_command(cmd):
+    """Search ``cmd`` in the ``PATH`` environment.
+
+    If found, return True.
+    If not found, return False.
+    """
+    return shutil.which(cmd) is not None
+
+
+# -- General configuration ------------------------------------------------
+
+# Add any Sphinx extensions in alphabetic order
+extensions = [
+    "automarkup",
+    "kernel_abi",
+    "kerneldoc",
+    "kernel_feat",
+    "kernel_include",
+    "kfigure",
+    "maintainers_include",
+    "parser_yaml",
+    "rstFlatTable",
+    "sphinx.ext.autodoc",
+    "sphinx.ext.autosectionlabel",
+    "sphinx.ext.ifconfig",
+    "translations",
+]
+# Since Sphinx version 3, the C function parser is more pedantic with regards
+# to type checking. Due to that, having macros at c:function cause problems.
+# Those needed to be escaped by using c_id_attributes[] array
+c_id_attributes = [
+    # GCC Compiler types not parsed by Sphinx:
+    "__restrict__",
+
+    # include/linux/compiler_types.h:
+    "__iomem",
+    "__kernel",
+    "noinstr",
+    "notrace",
+    "__percpu",
+    "__rcu",
+    "__user",
+    "__force",
+    "__counted_by_le",
+    "__counted_by_be",
+
+    # include/linux/compiler_attributes.h:
+    "__alias",
+    "__aligned",
+    "__aligned_largest",
+    "__always_inline",
+    "__assume_aligned",
+    "__cold",
+    "__attribute_const__",
+    "__copy",
+    "__pure",
+    "__designated_init",
+    "__visible",
+    "__printf",
+    "__scanf",
+    "__gnu_inline",
+    "__malloc",
+    "__mode",
+    "__no_caller_saved_registers",
+    "__noclone",
+    "__nonstring",
+    "__noreturn",
+    "__packed",
+    "__pure",
+    "__section",
+    "__always_unused",
+    "__maybe_unused",
+    "__used",
+    "__weak",
+    "noinline",
+    "__fix_address",
+    "__counted_by",
+
+    # include/linux/memblock.h:
+    "__init_memblock",
+    "__meminit",
+
+    # include/linux/init.h:
+    "__init",
+    "__ref",
+
+    # include/linux/linkage.h:
+    "asmlinkage",
+
+    # include/linux/btf.h
+    "__bpf_kfunc",
+]
+
+# Ensure that autosectionlabel will produce unique names
+autosectionlabel_prefix_document = True
+autosectionlabel_maxdepth = 2
+
+# Load math renderer:
+# For html builder, load imgmath only when its dependencies are met.
+# mathjax is the default math renderer since Sphinx 1.8.
+have_latex = have_command("latex")
+have_dvipng = have_command("dvipng")
+load_imgmath = have_latex and have_dvipng
+
+# Respect SPHINX_IMGMATH (for html docs only)
+if "SPHINX_IMGMATH" in os.environ:
+    env_sphinx_imgmath = os.environ["SPHINX_IMGMATH"]
+    if "yes" in env_sphinx_imgmath:
+        load_imgmath = True
+    elif "no" in env_sphinx_imgmath:
+        load_imgmath = False
+    else:
+        sys.stderr.write("Unknown env SPHINX_IMGMATH=%s ignored.\n" % env_sphinx_imgmath)
+
+if load_imgmath:
+    extensions.append("sphinx.ext.imgmath")
+    math_renderer = "imgmath"
+else:
+    math_renderer = "mathjax"
+
+# Add any paths that contain templates here, relative to this directory.
+templates_path = ["sphinx/templates"]
+
+# The suffixes of source filenames that will be automatically parsed
+source_suffix = {
+    ".rst": "restructuredtext",
+    ".yaml": "yaml",
+}
+
+# The encoding of source files.
+# source_encoding = 'utf-8-sig'
+
+# The master toctree document.
+master_doc = "index"
+
+# General information about the project.
+project = "The Linux Kernel"
+copyright = "The kernel development community"         # pylint: disable=W0622
+author = "The kernel development community"
+
+# The version info for the project you're documenting, acts as replacement for
+# |version| and |release|, also used in various other places throughout the
+# built documents.
+#
+# In a normal build, version and release are set to KERNELVERSION and
+# KERNELRELEASE, respectively, from the Makefile via Sphinx command line
+# arguments.
+#
+# The following code tries to extract the information by reading the Makefile,
+# when Sphinx is run directly (e.g. by Read the Docs).
+try:
+    makefile_version = None
+    makefile_patchlevel = None
+    with open("../Makefile", encoding="utf-8") as fp:
+        for line in fp:
+            key, val = [x.strip() for x in line.split("=", 2)]
+            if key == "VERSION":
+                makefile_version = val
+            elif key == "PATCHLEVEL":
+                makefile_patchlevel = val
+            if makefile_version and makefile_patchlevel:
+                break
+except Exception:
+    pass
+finally:
+    if makefile_version and makefile_patchlevel:
+        version = release = makefile_version + "." + makefile_patchlevel
+    else:
+        version = release = "unknown version"
+
+
+def get_cline_version():
+    """
+    HACK: There seems to be no easy way for us to get at the version and
+    release information passed in from the makefile...so go pawing through the
+    command-line options and find it for ourselves.
+    """
+
+    c_version = c_release = ""
+    for arg in sys.argv:
+        if arg.startswith("version="):
+            c_version = arg[8:]
+        elif arg.startswith("release="):
+            c_release = arg[8:]
+    if c_version:
+        if c_release:
+            return c_version + "-" + c_release
+        return c_version
+    return version  # Whatever we came up with before
+
+
+# The language for content autogenerated by Sphinx. Refer to documentation
+# for a list of supported languages.
+#
+# This is also used if you do content translation via gettext catalogs.
+# Usually you set "language" from the command line for these cases.
+language = "en"
+
+# There are two options for replacing |today|: either, you set today to some
+# non-false value, then it is used:
+# today = ''
+# Else, today_fmt is used as the format for a strftime call.
+# today_fmt = '%B %d, %Y'
+
+# The reST default role (used for this markup: `text`) to use for all
+# documents.
+# default_role = None
+
+# If true, '()' will be appended to :func: etc. cross-reference text.
+# add_function_parentheses = True
+
+# If true, the current module name will be prepended to all description
+# unit titles (such as .. function::).
+# add_module_names = True
+
+# If true, sectionauthor and moduleauthor directives will be shown in the
+# output. They are ignored by default.
+# show_authors = False
+
+# The name of the Pygments (syntax highlighting) style to use.
+pygments_style = "sphinx"
+
+# A list of ignored prefixes for module index sorting.
+# modindex_common_prefix = []
+
+# If true, keep warnings as "system message" paragraphs in the built documents.
+# keep_warnings = False
+
+# If true, `todo` and `todoList` produce output, else they produce nothing.
+todo_include_todos = False
+
+primary_domain = "c"
+highlight_language = "none"
+
+# -- Options for HTML output ----------------------------------------------
+
+# The theme to use for HTML and HTML Help pages.  See the documentation for
+# a list of builtin themes.
+
+# Default theme
+html_theme = "alabaster"
+html_css_files = []
+
+if "DOCS_THEME" in os.environ:
+    html_theme = os.environ["DOCS_THEME"]
+
+if html_theme in ["sphinx_rtd_theme", "sphinx_rtd_dark_mode"]:
+    # Read the Docs theme
+    try:
+        import sphinx_rtd_theme
+
+        html_theme_path = [sphinx_rtd_theme.get_html_theme_path()]
+
+        # Add any paths that contain custom static files (such as style sheets) here,
+        # relative to this directory. They are copied after the builtin static files,
+        # so a file named "default.css" will overwrite the builtin "default.css".
+        html_css_files = [
+            "theme_overrides.css",
+        ]
+
+        # Read the Docs dark mode override theme
+        if html_theme == "sphinx_rtd_dark_mode":
+            try:
+                import sphinx_rtd_dark_mode            # pylint: disable=W0611
+
+                extensions.append("sphinx_rtd_dark_mode")
+            except ImportError:
+                html_theme = "sphinx_rtd_theme"
+
+        if html_theme == "sphinx_rtd_theme":
+            # Add color-specific RTD normal mode
+            html_css_files.append("theme_rtd_colors.css")
+
+        html_theme_options = {
+            "navigation_depth": -1,
+        }
+
+    except ImportError:
+        html_theme = "alabaster"
+
+if "DOCS_CSS" in os.environ:
+    css = os.environ["DOCS_CSS"].split(" ")
+
+    for l in css:
+        html_css_files.append(l)
+
+if html_theme == "alabaster":
+    html_theme_options = {
+        "description": get_cline_version(),
+        "page_width": "65em",
+        "sidebar_width": "15em",
+        "fixed_sidebar": "true",
+        "font_size": "inherit",
+        "font_family": "serif",
+    }
+
+sys.stderr.write("Using %s theme\n" % html_theme)
+
+# Add any paths that contain custom static files (such as style sheets) here,
+# relative to this directory. They are copied after the builtin static files,
+# so a file named "default.css" will overwrite the builtin "default.css".
+html_static_path = ["sphinx-static"]
+
+# If true, Docutils "smart quotes" will be used to convert quotes and dashes
+# to typographically correct entities.  However, conversion of "--" to "—"
+# is not always what we want, so enable only quotes.
+smartquotes_action = "q"
+
+# Custom sidebar templates, maps document names to template names.
+# Note that the RTD theme ignores this
+html_sidebars = {"**": ["searchbox.html",
+                        "kernel-toc.html",
+                        "sourcelink.html"]}
+
+# about.html is available for alabaster theme. Add it at the front.
+if html_theme == "alabaster":
+    html_sidebars["**"].insert(0, "about.html")
+
+# The name of an image file (relative to this directory) to place at the top
+# of the sidebar.
+html_logo = "images/logo.svg"
+html_favicon = "images/logo.svg"
+
+# Output file base name for HTML help builder.
+htmlhelp_basename = "TheLinuxKerneldoc"
+
+# -- Options for LaTeX output ---------------------------------------------
+
+latex_elements = {
+    # The paper size ('letterpaper' or 'a4paper').
+    "papersize": "a4paper",
+    "passoptionstopackages": dedent(r"""
+        \PassOptionsToPackage{svgnames}{xcolor}
+    """),
+    # The font size ('10pt', '11pt' or '12pt').
+    "pointsize": "11pt",
+    # Needed to generate a .ind file
+    "printindex": r"\footnotesize\raggedright\printindex",
+    # Latex figure (float) alignment
+    # 'figure_align': 'htbp',
+    # Don't mangle with UTF-8 chars
+    "fontenc": "",
+    "inputenc": "",
+    "utf8extra": "",
+    # Set document margins
+    "sphinxsetup": dedent(r"""
+        hmargin=0.5in, vmargin=1in,
+        parsedliteralwraps=true,
+        verbatimhintsturnover=false,
+    """),
+    #
+    # Some of our authors are fond of deep nesting; tell latex to
+    # cope.
+    #
+    "maxlistdepth": "10",
+    # For CJK One-half spacing, need to be in front of hyperref
+    "extrapackages": r"\usepackage{setspace}",
+    "fontpkg": dedent(r"""
+        \usepackage{fontspec}
+        \setmainfont{DejaVu Serif}
+        \setsansfont{DejaVu Sans}
+        \setmonofont{DejaVu Sans Mono}
+        \newfontfamily\headingfont{DejaVu Serif}
+    """),
+    "preamble": dedent(r"""
+        % Load kerneldoc specific LaTeX settings
+        \input{kerneldoc-preamble.sty}
+    """)
+}
+
+# This will be filled up by config-inited event
+latex_documents = []
+
+# The name of an image file (relative to this directory) to place at the top of
+# the title page.
+# latex_logo = None
+
+# For "manual" documents, if this is true, then toplevel headings are parts,
+# not chapters.
+# latex_use_parts = False
+
+# If true, show page references after internal links.
+# latex_show_pagerefs = False
+
+# If true, show URL addresses after external links.
+# latex_show_urls = False
+
+# Documents to append as an appendix to all manuals.
+# latex_appendices = []
+
+# If false, no module index is generated.
+# latex_domain_indices = True
+
+# Additional LaTeX stuff to be copied to build directory
+latex_additional_files = [
+    "sphinx/kerneldoc-preamble.sty",
+]
+
+
+# -- Options for manual page output ---------------------------------------
+
+# One entry per manual page. List of tuples
+# (source start file, name, description, authors, manual section).
+man_pages = [
+    (master_doc, "thelinuxkernel", "The Linux Kernel Documentation", [author], 1)
+]
+
+# If true, show URL addresses after external links.
+# man_show_urls = False
+
+
+# -- Options for Texinfo output -------------------------------------------
+
+# Grouping the document tree into Texinfo files. List of tuples
+# (source start file, target name, title, author,
+#  dir menu entry, description, category)
+texinfo_documents = [(
+        master_doc,
+        "TheLinuxKernel",
+        "The Linux Kernel Documentation",
+        author,
+        "TheLinuxKernel",
+        "One line description of project.",
+        "Miscellaneous",
+    ),]
+
+# -- Options for Epub output ----------------------------------------------
+
+# Bibliographic Dublin Core info.
+epub_title = project
+epub_author = author
+epub_publisher = author
+epub_copyright = copyright
+
+# A list of files that should not be packed into the epub file.
+epub_exclude_files = ["search.html"]
+
+# =======
+# rst2pdf
+#
+# Grouping the document tree into PDF files. List of tuples
+# (source start file, target name, title, author, options).
+#
+# See the Sphinx chapter of https://ralsina.me/static/manual.pdf
+#
+# FIXME: Do not add the index file here; the result will be too big. Adding
+# multiple PDF files here actually tries to get the cross-referencing right
+# *between* PDF files.
+pdf_documents = [
+    ("kernel-documentation", "Kernel", "Kernel", "J. Random Bozo"),
+]
+
+kerneldoc_srctree = ".."
+
+# Add index link at the end of the root document for SPHINXDIRS builds.
+def add_subproject_index(app, docname, content):
+    # Only care about root documents
+    if docname != master_doc:
+        return
+
+    # Add the index link at the root of translations, but not at the root of
+    # individual translations. They have their own language specific links.
+    rel = os.path.relpath(app.srcdir, start=kern_doc_dir).split('/')
+    if rel[0] == 'translations' and len(rel) > 1:
+        return
+
+    # Only add the link for SPHINXDIRS HTML builds
+    if not app.builder.tags.has('subproject') or not app.builder.tags.has('html'):
+        return
+
+    # The include directive needs a relative path from the srcdir
+    rel = os.path.relpath(os.path.join(kern_doc_dir, 'sphinx-includes/subproject-index.rst'),
+                          start=app.srcdir)
+
+    content[0] += f'\n.. include:: {rel}\n\n'
+
+def setup(app):
+    """Patterns need to be updated at init time on older Sphinx versions"""
+
+    app.connect('config-inited', config_init)
+    app.connect('source-read', add_subproject_index)