Merge tag 'docs-5.3' of git://git.lwn.net/linux

Pull Documentation updates from Jonathan Corbet:
 "It's been a relatively busy cycle for docs:

   - A fair pile of RST conversions, many from Mauro. These create more
     than the usual number of simple but annoying merge conflicts with
     other trees, unfortunately. He has a lot more of these waiting on
     the wings that, I think, will go to you directly later on.

   - A new document on how to use merges and rebases in kernel repos,
     and one on Spectre vulnerabilities.

   - Various improvements to the build system, including automatic
     markup of function() references because some people, for reasons I
     will never understand, were of the opinion that
     :c:func:``function()`` is unattractive and not fun to type.

   - We now recommend using sphinx 1.7, but still support back to 1.4.

   - Lots of smaller improvements, warning fixes, typo fixes, etc"

* tag 'docs-5.3' of git://git.lwn.net/linux: (129 commits)
  docs: automarkup.py: ignore exceptions when seeking for xrefs
  docs: Move binderfs to admin-guide
  Disable Sphinx SmartyPants in HTML output
  doc: RCU callback locks need only _bh, not necessarily _irq
  docs: format kernel-parameters -- as code
  Doc : doc-guide : Fix a typo
  platform: x86: get rid of a non-existent document
  Add the RCU docs to the core-api manual
  Documentation: RCU: Add TOC tree hooks
  Documentation: RCU: Rename txt files to rst
  Documentation: RCU: Convert RCU UP systems to reST
  Documentation: RCU: Convert RCU linked list to reST
  Documentation: RCU: Convert RCU basic concepts to reST
  docs: filesystems: Remove uneeded .rst extension on toctables
  scripts/sphinx-pre-install: fix out-of-tree build
  docs: zh_CN: submitting-drivers.rst: Remove a duplicated Documentation/
  Documentation: PGP: update for newer HW devices
  Documentation: Add section about CPU vulnerabilities for Spectre
  Documentation: platform: Delete x86-laptop-drivers.txt
  docs: Note that :c:func: should no longer be used
  ...

1 files changed, 101 insertions, 0 deletions

diff --git a/Documentation/sphinx/automarkup.py b/Documentation/sphinx/automarkup.py
new file mode 100644
index 000000000000..77e89c1956d7
--- /dev/null
+++ b/Documentation/sphinx/automarkup.py
@@ -0,0 +1,101 @@
+# SPDX-License-Identifier: GPL-2.0
+# Copyright 2019 Jonathan Corbet <corbet@lwn.net>
+#
+# Apply kernel-specific tweaks after the initial document processing
+# has been done.
+#
+from docutils import nodes
+from sphinx import addnodes
+from sphinx.environment import NoUri
+import re
+
+#
+# Regex nastiness.  Of course.
+# Try to identify "function()" that's not already marked up some
+# other way.  Sphinx doesn't like a lot of stuff right after a
+# :c:func: block (i.e. ":c:func:`mmap()`s" flakes out), so the last
+# bit tries to restrict matches to things that won't create trouble.
+#
+RE_function = re.compile(r'([\w_][\w\d_]+\(\))')
+
+#
+# Many places in the docs refer to common system calls.  It is
+# pointless to try to cross-reference them and, as has been known
+# to happen, somebody defining a function by these names can lead
+# to the creation of incorrect and confusing cross references.  So
+# just don't even try with these names.
+#
+Skipfuncs = [ 'open', 'close', 'read', 'write', 'fcntl', 'mmap'
+              'select', 'poll', 'fork', 'execve', 'clone', 'ioctl']
+
+#
+# Find all occurrences of function() and try to replace them with
+# appropriate cross references.
+#
+def markup_funcs(docname, app, node):
+    cdom = app.env.domains['c']
+    t = node.astext()
+    done = 0
+    repl = [ ]
+    for m in RE_function.finditer(t):
+        #
+        # Include any text prior to function() as a normal text node.
+        #
+        if m.start() > done:
+            repl.append(nodes.Text(t[done:m.start()]))
+        #
+        # Go through the dance of getting an xref out of the C domain
+        #
+        target = m.group(1)[:-2]
+        target_text = nodes.Text(target + '()')
+        xref = None
+        if target not in Skipfuncs:
+            lit_text = nodes.literal(classes=['xref', 'c', 'c-func'])
+            lit_text += target_text
+            pxref = addnodes.pending_xref('', refdomain = 'c',
+                                          reftype = 'function',
+                                          reftarget = target, modname = None,
+                                          classname = None)
+            #
+            # XXX The Latex builder will throw NoUri exceptions here,
+            # work around that by ignoring them.
+            #
+            try:
+                xref = cdom.resolve_xref(app.env, docname, app.builder,
+                                         'function', target, pxref, lit_text)
+            except NoUri:
+                xref = None
+        #
+        # Toss the xref into the list if we got it; otherwise just put
+        # the function text.
+        #
+        if xref:
+            repl.append(xref)
+        else:
+            repl.append(target_text)
+        done = m.end()
+    if done < len(t):
+        repl.append(nodes.Text(t[done:]))
+    return repl
+
+def auto_markup(app, doctree, name):
+    #
+    # This loop could eventually be improved on.  Someday maybe we
+    # want a proper tree traversal with a lot of awareness of which
+    # kinds of nodes to prune.  But this works well for now.
+    #
+    # The nodes.literal test catches ``literal text``, its purpose is to
+    # avoid adding cross-references to functions that have been explicitly
+    # marked with cc:func:.
+    #
+    for para in doctree.traverse(nodes.paragraph):
+        for node in para.traverse(nodes.Text):
+            if not isinstance(node.parent, nodes.literal):
+                node.parent.replace(node, markup_funcs(name, app, node))
+
+def setup(app):
+    app.connect('doctree-resolved', auto_markup)
+    return {
+        'parallel_read_safe': True,
+        'parallel_write_safe': True,
+        }