Merge branch 'alabaster-rb' into docs-mw

For a long time we have rejoiced that our HTML output from Sphinx is far
better than what we got from the old DocBook toolchain.  But it still
leaves a lot to be desired; the following is an attempt to improve the
situation somewhat.

Sphinx has a theming mechanism for HTML rendering.  Since the kernel's
adoption of Sphinx, we have been using the "Read The Docs" theme — a choice
made in a bit of a hurry to have *something* while figuring out the rest.
RTD is OK, but it is not hugely attractive, requires the installation of an
extra package, and does not observe all of the Sphinx configuration
parameters.  Among other things, that makes it hard to put reasonable
contents into the left column in the HTML output.

The Alabaster theme is the default for Sphinx installations, and is bundled
with Sphinx itself.  It has (IMO) nicer output and gives us the control
that we need.

So: switch to Alabaster.  Additional patches adjust the documentation and
remove the RTD references from scripts/sphinx-pre-install.

The penultimate patch changes the way that kerneldoc declarations are
rendered to (IMO) improve readability.  That requires some changes to
kernel-doc to output a new container block and some CSS tweaks to improve
things overall.

It should be noted that I have a long history of inflicting ugly web
designs on the net; this work is a start, but I think we could do far
better yet.  It would be great if somebody who actually enjoys working with
CSS and such would help to improve what we have.

6 files changed, 93 insertions, 220 deletions

diff --git a/Documentation/conf.py b/Documentation/conf.py
index b50c85083149..6ab47833ab6c 100644
--- a/Documentation/conf.py
+++ b/Documentation/conf.py
@@ -194,6 +194,24 @@ finally:
     else:
         version = release = "unknown 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.
+#
+def get_cline_version():
+    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.
 #
@@ -247,7 +265,7 @@ highlight_language = 'none'
 # a list of builtin themes.
 
 # Default theme
-html_theme = 'sphinx_rtd_theme'
+html_theme = 'alabaster'
 html_css_files = []
 
 if "DOCS_THEME" in os.environ:
@@ -279,7 +297,7 @@ if html_theme == 'sphinx_rtd_theme' or html_theme == 'sphinx_rtd_dark_mode':
                 html_css_files.append('theme_rtd_colors.css')
 
     except ImportError:
-        html_theme = 'classic'
+        html_theme = 'alabaster'
 
 if "DOCS_CSS" in os.environ:
     css = os.environ["DOCS_CSS"].split(" ")
@@ -295,127 +313,28 @@ if major <= 1 and minor < 8:
     for l in html_css_files:
         html_context['css_files'].append('_static/' + l)
 
-if  html_theme == 'classic':
+if  html_theme == 'alabaster':
     html_theme_options = {
-        'rightsidebar':        False,
-        'stickysidebar':       True,
-        'collapsiblesidebar':  True,
-        'externalrefs':        False,
-
-        'footerbgcolor':       "white",
-        'footertextcolor':     "white",
-        'sidebarbgcolor':      "white",
-        'sidebarbtncolor':     "black",
-        'sidebartextcolor':    "black",
-        'sidebarlinkcolor':    "#686bff",
-        'relbarbgcolor':       "#133f52",
-        'relbartextcolor':     "white",
-        'relbarlinkcolor':     "white",
-        'bgcolor':             "white",
-        'textcolor':           "black",
-        'headbgcolor':         "#f2f2f2",
-        'headtextcolor':       "#20435c",
-        'headlinkcolor':       "#c60f0f",
-        'linkcolor':           "#355f7c",
-        'visitedlinkcolor':    "#355f7c",
-        'codebgcolor':         "#3f3f3f",
-        'codetextcolor':       "white",
-
-        'bodyfont':            "serif",
-        'headfont':            "sans-serif",
+        'description': get_cline_version(),
+        'font_size': '10pt',
+        'page_width': '65em',
+        'sidebar_width': '15em',
     }
 
 sys.stderr.write("Using %s theme\n" % html_theme)
 
-# Theme options are theme-specific and customize the look and feel of a theme
-# further.  For a list of options available for each theme, see the
-# documentation.
-#html_theme_options = {}
-
-# Add any paths that contain custom themes here, relative to this directory.
-#html_theme_path = []
-
-# The name for this set of Sphinx documents.  If None, it defaults to
-# "<project> v<release> documentation".
-#html_title = None
-
-# A shorter title for the navigation bar.  Default is the same as html_title.
-#html_short_title = None
-
-# The name of an image file (relative to this directory) to place at the top
-# of the sidebar.
-#html_logo = None
-
-# The name of an image file (within the static path) to use as favicon of the
-# docs.  This file should be a Windows icon file (.ico) being 16x16 or 32x32
-# pixels large.
-#html_favicon = None
-
 # 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']
 
-# Add any extra paths that contain custom files (such as robots.txt or
-# .htaccess) here, relative to this directory. These files are copied
-# directly to the root of the documentation.
-#html_extra_path = []
-
-# If not '', a 'Last updated on:' timestamp is inserted at every page bottom,
-# using the given strftime format.
-#html_last_updated_fmt = '%b %d, %Y'
-
 # If true, SmartyPants will be used to convert quotes and dashes to
 # typographically correct entities.
 html_use_smartypants = False
 
 # Custom sidebar templates, maps document names to template names.
-# 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.
-#html_additional_pages = {}
-
-# If false, no module index is generated.
-#html_domain_indices = True
-
-# If false, no index is generated.
-#html_use_index = True
-
-# If true, the index is split into individual pages for each letter.
-#html_split_index = False
-
-# If true, links to the reST sources are added to the pages.
-#html_show_sourcelink = True
-
-# If true, "Created using Sphinx" is shown in the HTML footer. Default is True.
-#html_show_sphinx = True
-
-# If true, "(C) Copyright ..." is shown in the HTML footer. Default is True.
-#html_show_copyright = True
-
-# If true, an OpenSearch description file will be output, and all pages will
-# contain a <link> tag referring to it.  The value of this option must be the
-# base URL from which the finished HTML is served.
-#html_use_opensearch = ''
-
-# This is the file name suffix for HTML files (e.g. ".xhtml").
-#html_file_suffix = None
-
-# Language to be used for generating the HTML full-text search index.
-# Sphinx supports the following languages:
-#   'da', 'de', 'en', 'es', 'fi', 'fr', 'h', 'it', 'ja'
-#   'nl', 'no', 'pt', 'ro', 'r', 'sv', 'tr'
-#html_search_language = 'en'
-
-# A dictionary with options for the search language support, empty by default.
-# Now only 'ja' uses this config value
-#html_search_options = {'type': 'default'}
-
-# The name of a javascript file (relative to the configuration directory) that
-# implements a search results scorer. If empty, the default will be used.
-#html_search_scorer = 'scorer.js'
+# Note that the RTD theme ignores this
+html_sidebars = { '**': ["about.html", 'searchbox.html', 'localtoc.html', 'sourcelink.html']}
 
 # Output file base name for HTML help builder.
 htmlhelp_basename = 'TheLinuxKerneldoc'
@@ -558,19 +477,6 @@ texinfo_documents = [
      'Miscellaneous'),
 ]
 
-# Documents to append as an appendix to all manuals.
-#texinfo_appendices = []
-
-# If false, no module index is generated.
-#texinfo_domain_indices = True
-
-# How to display URL addresses: 'footnote', 'no', or 'inline'.
-#texinfo_show_urls = 'footnote'
-
-# If true, do not generate a @detailmenu in the "Top" node's menu.
-#texinfo_no_detailmenu = False
-
-
 # -- Options for Epub output ----------------------------------------------
 
 # Bibliographic Dublin Core info.
@@ -579,67 +485,9 @@ epub_author = author
 epub_publisher = author
 epub_copyright = copyright
 
-# The basename for the epub file. It defaults to the project name.
-#epub_basename = project
-
-# The HTML theme for the epub output. Since the default themes are not
-# optimized for small screen space, using the same theme for HTML and epub
-# output is usually not wise. This defaults to 'epub', a theme designed to save
-# visual space.
-#epub_theme = 'epub'
-
-# The language of the text. It defaults to the language option
-# or 'en' if the language is not set.
-#epub_language = ''
-
-# The scheme of the identifier. Typical schemes are ISBN or URL.
-#epub_scheme = ''
-
-# The unique identifier of the text. This can be a ISBN number
-# or the project homepage.
-#epub_identifier = ''
-
-# A unique identification for the text.
-#epub_uid = ''
-
-# A tuple containing the cover image and cover page html template filenames.
-#epub_cover = ()
-
-# A sequence of (type, uri, title) tuples for the guide element of content.opf.
-#epub_guide = ()
-
-# HTML files that should be inserted before the pages created by sphinx.
-# The format is a list of tuples containing the path and title.
-#epub_pre_files = []
-
-# HTML files that should be inserted after the pages created by sphinx.
-# The format is a list of tuples containing the path and title.
-#epub_post_files = []
-
 # A list of files that should not be packed into the epub file.
 epub_exclude_files = ['search.html']
 
-# The depth of the table of contents in toc.ncx.
-#epub_tocdepth = 3
-
-# Allow duplicate toc entries.
-#epub_tocdup = True
-
-# Choose between 'default' and 'includehidden'.
-#epub_tocscope = 'default'
-
-# Fix unsupported image types using the Pillow.
-#epub_fix_images = False
-
-# Scale large images.
-#epub_max_image_width = 0
-
-# How to display URL addresses: 'footnote', 'no', or 'inline'.
-#epub_show_urls = 'inline'
-
-# If false, no index is generated.
-#epub_use_index = True
-
 #=======
 # rst2pdf
 #
diff --git a/Documentation/doc-guide/sphinx.rst b/Documentation/doc-guide/sphinx.rst
index c708cec889af..23edb427e76f 100644
--- a/Documentation/doc-guide/sphinx.rst
+++ b/Documentation/doc-guide/sphinx.rst
@@ -147,11 +147,9 @@ section of ``make help``. The generated documentation is placed in
 format-specific subdirectories under ``Documentation/output``.
 
 To generate documentation, Sphinx (``sphinx-build``) must obviously be
-installed. For prettier HTML output, the Read the Docs Sphinx theme
-(``sphinx_rtd_theme``) is used if available. For PDF output you'll also need
-``XeLaTeX`` and ``convert(1)`` from ImageMagick
-(https://www.imagemagick.org).\ [#ink]_
-All of these are widely available and packaged in distributions.
+installed.  For PDF output you'll also need ``XeLaTeX`` and ``convert(1)``
+from ImageMagick (https://www.imagemagick.org).\ [#ink]_ All of these are
+widely available and packaged in distributions.
 
 To pass extra options to Sphinx, you can use the ``SPHINXOPTS`` make
 variable. For example, use ``make SPHINXOPTS=-v htmldocs`` to get more verbose
@@ -160,12 +158,8 @@ output.
 It is also possible to pass an extra DOCS_CSS overlay file, in order to customize
 the html layout, by using the ``DOCS_CSS`` make variable.
 
-By default, the build will try to use the Read the Docs sphinx theme:
-
-    https://github.com/readthedocs/sphinx_rtd_theme
-
-If the theme is not available, it will fall-back to the classic one.
-
+By default, the "Alabaster" theme is used to build the HTML documentation;
+this theme is bundled with Sphinx and need not be installed separately.
 The Sphinx theme can be overridden by using the ``DOCS_THEME`` make variable.
 
 There is another make variable ``SPHINXDIRS``, which is useful when test
diff --git a/Documentation/sphinx-static/custom.css b/Documentation/sphinx-static/custom.css
new file mode 100644
index 000000000000..9b36f7abd24f
--- /dev/null
+++ b/Documentation/sphinx-static/custom.css
@@ -0,0 +1,28 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * CSS tweaks for the Alabaster theme
+ */
+
+/* Shrink the headers a bit */
+div.body h1 { font-size: 180%; }
+div.body h2 { font-size: 150%; }
+div.body h3 { font-size: 130%; }
+
+/* Tighten up the layout slightly */
+div.body { padding: 0 15px 0 10px; }
+div.sphinxsidebarwrapper { padding: 1em 0.4em; }
+/* Tweak document margins and don't force width */
+div.document {
+    margin: 20px 10px 0 10px; 
+    width: auto;
+}
+
+/*
+ * Parameters for the display of function prototypes and such included
+ * from C source files.
+ */
+dl.function, dl.struct, dl.enum { margin-top: 2em; background-color: #ecf0f3; }
+/* indent lines 2+ of multi-line function prototypes */
+dl.function dt { margin-left: 10em; text-indent: -10em; }
+dt.sig-object { font-size: larger; }
+div.kernelindent { margin-left: 2em; margin-right: 4em; }
diff --git a/Documentation/sphinx/requirements.txt b/Documentation/sphinx/requirements.txt
index 2c573541ab71..335b53df35e2 100644
--- a/Documentation/sphinx/requirements.txt
+++ b/Documentation/sphinx/requirements.txt
@@ -1,4 +1,3 @@
 # jinja2>=3.1 is not compatible with Sphinx<4.0
 jinja2<3.1
-sphinx_rtd_theme
 Sphinx==2.4.4
diff --git a/scripts/kernel-doc b/scripts/kernel-doc
index aea04365bc69..11bafc8e85ab 100755
--- a/scripts/kernel-doc
+++ b/scripts/kernel-doc
@@ -866,48 +866,53 @@ sub output_function_rst(%) {
 	print "\n";
     }
 
-    print "**Parameters**\n\n";
+    #
+    # Put our descriptive text into a container (thus an HTML <div>) to help
+    # set the function prototypes apart.
+    #
+    print ".. container:: kernelindent\n\n";
     $lineprefix = "  ";
+    print $lineprefix . "**Parameters**\n\n";
     foreach $parameter (@{$args{'parameterlist'}}) {
 	my $parameter_name = $parameter;
 	$parameter_name =~ s/\[.*//;
 	$type = $args{'parametertypes'}{$parameter};
 
 	if ($type ne "") {
-	    print "``$type``\n";
+	    print $lineprefix . "``$type``\n";
 	} else {
-	    print "``$parameter``\n";
+	    print $lineprefix . "``$parameter``\n";
 	}
 
         print_lineno($parameterdesc_start_lines{$parameter_name});
 
+	$lineprefix = "    ";
 	if (defined($args{'parameterdescs'}{$parameter_name}) &&
 	    $args{'parameterdescs'}{$parameter_name} ne $undescribed) {
 	    output_highlight_rst($args{'parameterdescs'}{$parameter_name});
 	} else {
-	    print "  *undescribed*\n";
+	    print $lineprefix . "*undescribed*\n";
 	}
+	$lineprefix = "  ";
 	print "\n";
     }
 
-    $lineprefix = $oldprefix;
     output_section_rst(@_);
+    $lineprefix = $oldprefix;
 }
 
 sub output_section_rst(%) {
     my %args = %{$_[0]};
     my $section;
     my $oldprefix = $lineprefix;
-    $lineprefix = "";
 
     foreach $section (@{$args{'sectionlist'}}) {
-	print "**$section**\n\n";
+	print $lineprefix . "**$section**\n\n";
         print_lineno($section_start_lines{$section});
 	output_highlight_rst($args{'sections'}{$section});
 	print "\n";
     }
     print "\n";
-    $lineprefix = $oldprefix;
 }
 
 sub output_enum_rst(%) {
@@ -915,6 +920,7 @@ sub output_enum_rst(%) {
     my ($parameter);
     my $oldprefix = $lineprefix;
     my $count;
+    my $outer;
 
     if ($sphinx_major < 3) {
 	my $name = "enum " . $args{'enum'};
@@ -924,22 +930,25 @@ sub output_enum_rst(%) {
 	print "\n\n.. c:enum:: " . $name . "\n\n";
     }
     print_lineno($declaration_start_line);
-    $lineprefix = "   ";
+    $lineprefix = "  ";
     output_highlight_rst($args{'purpose'});
     print "\n";
 
-    print "**Constants**\n\n";
-    $lineprefix = "  ";
+    print ".. container:: kernelindent\n\n";
+    $outer = $lineprefix . "  ";
+    $lineprefix = $outer . "  ";
+    print $outer . "**Constants**\n\n";
     foreach $parameter (@{$args{'parameterlist'}}) {
-	print "``$parameter``\n";
+	print $outer . "``$parameter``\n";
+
 	if ($args{'parameterdescs'}{$parameter} ne $undescribed) {
 	    output_highlight_rst($args{'parameterdescs'}{$parameter});
 	} else {
-	    print "  *undescribed*\n";
+	    print $lineprefix . "*undescribed*\n";
 	}
 	print "\n";
     }
-
+    print "\n";
     $lineprefix = $oldprefix;
     output_section_rst(@_);
 }
@@ -982,18 +991,19 @@ sub output_struct_rst(%) {
 	}
     }
     print_lineno($declaration_start_line);
-    $lineprefix = "   ";
+    $lineprefix = "  ";
     output_highlight_rst($args{'purpose'});
     print "\n";
 
-    print "**Definition**\n\n";
-    print "::\n\n";
+    print ".. container:: kernelindent\n\n";
+    print $lineprefix . "**Definition**::\n\n";
     my $declaration = $args{'definition'};
-    $declaration =~ s/\t/  /g;
-    print "  " . $args{'type'} . " " . $args{'struct'} . " {\n$declaration  };\n\n";
+    $lineprefix = $lineprefix . "  ";
+    $declaration =~ s/\t/$lineprefix/g;
+    print $lineprefix . $args{'type'} . " " . $args{'struct'} . " {\n$declaration" . $lineprefix . "};\n\n";
 
-    print "**Members**\n\n";
     $lineprefix = "  ";
+    print $lineprefix . "**Members**\n\n";
     foreach $parameter (@{$args{'parameterlist'}}) {
 	($parameter =~ /^#/) && next;
 
@@ -1003,8 +1013,10 @@ sub output_struct_rst(%) {
 	($args{'parameterdescs'}{$parameter_name} ne $undescribed) || next;
 	$type = $args{'parametertypes'}{$parameter};
         print_lineno($parameterdesc_start_lines{$parameter_name});
-	print "``" . $parameter . "``\n";
+	print $lineprefix . "``" . $parameter . "``\n";
+	$lineprefix = "    ";
 	output_highlight_rst($args{'parameterdescs'}{$parameter_name});
+	$lineprefix = "  ";
 	print "\n";
     }
     print "\n";
diff --git a/scripts/sphinx-pre-install b/scripts/sphinx-pre-install
index ec84fc62774e..1fb88fdceec3 100755
--- a/scripts/sphinx-pre-install
+++ b/scripts/sphinx-pre-install
@@ -362,7 +362,6 @@ sub give_debian_hints()
 {
 	my %map = (
 		"python-sphinx"		=> "python3-sphinx",
-		"sphinx_rtd_theme"	=> "python3-sphinx-rtd-theme",
 		"ensurepip"		=> "python3-venv",
 		"virtualenv"		=> "virtualenv",
 		"dot"			=> "graphviz",
@@ -397,7 +396,6 @@ sub give_redhat_hints()
 {
 	my %map = (
 		"python-sphinx"		=> "python3-sphinx",
-		"sphinx_rtd_theme"	=> "python3-sphinx_rtd_theme",
 		"virtualenv"		=> "python3-virtualenv",
 		"dot"			=> "graphviz",
 		"convert"		=> "ImageMagick",
@@ -475,7 +473,6 @@ sub give_opensuse_hints()
 {
 	my %map = (
 		"python-sphinx"		=> "python3-sphinx",
-		"sphinx_rtd_theme"	=> "python3-sphinx_rtd_theme",
 		"virtualenv"		=> "python3-virtualenv",
 		"dot"			=> "graphviz",
 		"convert"		=> "ImageMagick",
@@ -523,7 +520,6 @@ sub give_mageia_hints()
 {
 	my %map = (
 		"python-sphinx"		=> "python3-sphinx",
-		"sphinx_rtd_theme"	=> "python3-sphinx_rtd_theme",
 		"virtualenv"		=> "python3-virtualenv",
 		"dot"			=> "graphviz",
 		"convert"		=> "ImageMagick",
@@ -567,7 +563,6 @@ sub give_mageia_hints()
 sub give_arch_linux_hints()
 {
 	my %map = (
-		"sphinx_rtd_theme"	=> "python-sphinx_rtd_theme",
 		"virtualenv"		=> "python-virtualenv",
 		"dot"			=> "graphviz",
 		"convert"		=> "imagemagick",
@@ -598,7 +593,6 @@ sub give_arch_linux_hints()
 sub give_gentoo_hints()
 {
 	my %map = (
-		"sphinx_rtd_theme"	=> "dev-python/sphinx_rtd_theme",
 		"virtualenv"		=> "dev-python/virtualenv",
 		"dot"			=> "media-gfx/graphviz",
 		"convert"		=> "media-gfx/imagemagick",
@@ -895,7 +889,6 @@ sub recommend_sphinx_version($)
 	$verbose_warn_install = 0;
 
 	add_package("python-sphinx", 0);
-	check_python_module("sphinx_rtd_theme", 1);
 
 	check_distros();
 
@@ -968,7 +961,6 @@ sub check_needs()
 	check_perl_module("Pod::Usage", 0);
 	check_program("make", 0);
 	check_program("gcc", 0);
-	check_python_module("sphinx_rtd_theme", 1) if (!$virtualenv);
 	check_program("dot", 1);
 	check_program("convert", 1);