Merge tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Fix error output of boot instance creation failure

   Currently if a boot instance creation fails, instead of printing out
   the name of the instance that failed, it prints "(null)". That is
   because it prints "cur_str" that had already been processed by
   strsep(). Print the saved name instead.

   While at it, print the error code of the failure.

 - Fix use-after-free for same named historgrams

   Histograms can be named so that they can be used in multiple events.
   But if the named histogram has a variable attached, the second event
   that uses the named histogram which duplicates it and needs to free
   the original after duplication leaves the old variable in place and
   still visible. If another histogram uses than variable, it will use
   the stale one which will try to reference the freed duplicate
   histogram and crash the kernel.

   Free the duplicate variables along with the duplicated histogram
   data.

 - Check return value of kthread_run() in event self test

   The events self tests uses a kthread for testing but does not check
   if it succeeded in creating a kthread. If the kthread creation were
   to fail, the code will still try to call kthread_stop() on the error
   returned.

 - Fix race between reading trace_pipe and updating subbuffer size

   If a user is reading the trace_pipe file at the same time they update
   the ring buffer sub-buffer size, can cause the trace_pipe read to
   read stale data. Add trace_access_lock() around updating the ring
   buffer sub-buffer size.

 - Fix eventfs_inode on failure path in creation of the events directory

   In the creation of the "events" directory, if after allocating the
   eventfs_inode a failure is detected, it calls cleanup_ei() which
   calls free_ei(). The free_ei() will test if eventfs_inode being freed
   has no children. It is a bug if it does. But on the failure case of
   the creation of the "events" directory, the children lists have not
   yet been initialized and the free will trigger a warning because
   list_empty() on an uninitialized list returns false.

   Move the initialization into init_ei() where it makes more sense and
   makes sure that a created eventfs_inode has its lists initialized
   upon creation.

 - Check return value of kthread_run() in ftrace direct sample code

   The sample code that shows how to use the ftrace direct calls does
   not test the return of kthread_run() to see if it succeeds. Return a
   failure if the kthread_run() doesn't succeed.

 - Clear user events state on fork in case of alloc failure

   On fork, the child gets a pointer to the parent's user events state.
   It makes a copy of it then updates the child's pointer to it. But if
   the allocation fails, the duplication function leaves the child with
   a pointer to its parent's descriptor. When the child cleans up its
   data, it will free the parent's descriptor while the parent is still
   using it.

   In the duplication function, set the child's user_event_mm to NULL
   before testing if the allocation succeeded, and when it exits it will
   not free the parent's descriptor.

 - Fix retry exhaustion in simple ring buffer reader swap

   simple_ring_buffer_swap_reader_page() starts with retry set to 8 and
   post-decrements it only after a failed link replacement. On the final
   attempt, a successful replacement leaves retry at zero, while a
   failed replacement leaves it at -1.

   But the check for success expects the retry value to be non-zero and
   exits with an error on zero. This is the opposite result. Fix it.

 - Fail nicely when the remote swap_reader_page() returns an error

   Currently, if the swap_reader_page() of a remote buffer fails, it
   triggers a WARN_ON_ONCE() and continues normally. Instead, have it
   exit with an error and a pr_warn() print instead of a full WARNING.

* tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  ring-buffer: Stop remote reader update when page swap fails
  tracing: Fix retry exhaustion in simple ring buffer reader swap
  tracing/user_events: Clear copied tracing state before fork duplication
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-modify
  eventfs: Initialize ei->children and ei->list in init_ei()
  tracing: Fix use-after-free in trace_pipe read on sub-buffer order change
  tracing: Fix crash passing ERR_PTR to kthread_stop()
  tracing: Fix use-after-free with same-name named triggers
  tracing: Fix logged instance name on creation failure

1 files changed, 655 insertions, 0 deletions

diff --git a/Documentation/sphinx/kfigure.py b/Documentation/sphinx/kfigure.py
new file mode 100644
index 000000000..ad495c0da
--- /dev/null
+++ b/Documentation/sphinx/kfigure.py
@@ -0,0 +1,655 @@
+# -*- coding: utf-8; mode: python -*-
+# SPDX-License-Identifier: GPL-2.0
+# pylint: disable=C0103, R0903, R0912, R0915
+"""
+    scalable figure and image handling
+    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+    Sphinx extension which implements scalable image handling.
+
+    :copyright:  Copyright (C) 2016  Markus Heiser
+    :license:    GPL Version 2, June 1991 see Linux/COPYING for details.
+
+    The build for image formats depend on image's source format and output's
+    destination format. This extension implement methods to simplify image
+    handling from the author's POV. Directives like ``kernel-figure`` implement
+    methods *to* always get the best output-format even if some tools are not
+    installed. For more details take a look at ``convert_image(...)`` which is
+    the core of all conversions.
+
+    * ``.. kernel-image``: for image handling / a ``.. image::`` replacement
+
+    * ``.. kernel-figure``: for figure handling / a ``.. figure::`` replacement
+
+    * ``.. kernel-render``: for render markup / a concept to embed *render*
+      markups (or languages). Supported markups (see ``RENDER_MARKUP_EXT``)
+
+      - ``DOT``: render embedded Graphviz's **DOC**
+      - ``SVG``: render embedded Scalable Vector Graphics (**SVG**)
+      - ... *developable*
+
+    Used tools:
+
+    * ``dot(1)``: Graphviz (https://www.graphviz.org). If Graphviz is not
+      available, the DOT language is inserted as literal-block.
+      For conversion to PDF, ``rsvg-convert(1)`` of librsvg
+      (https://gitlab.gnome.org/GNOME/librsvg) is used when available.
+
+    * SVG to PDF: To generate PDF, you need at least one of this tools:
+
+      - ``convert(1)``: ImageMagick (https://www.imagemagick.org)
+      - ``inkscape(1)``: Inkscape (https://inkscape.org/)
+
+    List of customizations:
+
+    * generate PDF from SVG / used by PDF (LaTeX) builder
+
+    * generate SVG (html-builder) and PDF (latex-builder) from DOT files.
+      DOT: see https://www.graphviz.org/content/dot-language
+
+    """
+
+import os
+from os import path
+import subprocess
+from hashlib import sha1
+import re
+from docutils import nodes
+from docutils.statemachine import ViewList
+from docutils.parsers.rst import directives
+from docutils.parsers.rst.directives import images
+import sphinx
+from sphinx.util.nodes import clean_astext
+from sphinx.util import logging
+
+Figure = images.Figure
+
+__version__  = '1.0.0'
+
+logger = logging.getLogger('kfigure')
+
+# simple helper
+# -------------
+
+def which(cmd):
+    """Searches the ``cmd`` in the ``PATH`` environment.
+
+    This *which* searches the PATH for executable ``cmd`` . First match is
+    returned, if nothing is found, ``None` is returned.
+    """
+    envpath = os.environ.get('PATH', None) or os.defpath
+    for folder in envpath.split(os.pathsep):
+        fname = folder + os.sep + cmd
+        if path.isfile(fname):
+            return fname
+
+def mkdir(folder, mode=0o775):
+    if not path.isdir(folder):
+        os.makedirs(folder, mode)
+
+def file2literal(fname):
+    with open(fname, "r") as src:
+        data = src.read()
+        node = nodes.literal_block(data, data)
+    return node
+
+def isNewer(path1, path2):
+    """Returns True if ``path1`` is newer than ``path2``
+
+    If ``path1`` exists and is newer than ``path2`` the function returns
+    ``True`` is returned otherwise ``False``
+    """
+    return (path.exists(path1)
+            and os.stat(path1).st_ctime > os.stat(path2).st_ctime)
+
+def pass_handle(self, node):           # pylint: disable=W0613
+    pass
+
+# setup conversion tools and sphinx extension
+# -------------------------------------------
+
+# Graphviz's dot(1) support
+dot_cmd = None
+# dot(1) -Tpdf should be used
+dot_Tpdf = False
+
+# ImageMagick' convert(1) support
+convert_cmd = None
+
+# librsvg's rsvg-convert(1) support
+rsvg_convert_cmd = None
+
+# Inkscape's inkscape(1) support
+inkscape_cmd = None
+# Inkscape prior to 1.0 uses different command options
+inkscape_ver_one = False
+
+
+def setup(app):
+    # check toolchain first
+    app.connect('builder-inited', setupTools)
+
+    # image handling
+    app.add_directive("kernel-image",  KernelImage)
+    app.add_node(kernel_image,
+                 html    = (visit_kernel_image, pass_handle),
+                 latex   = (visit_kernel_image, pass_handle),
+                 texinfo = (visit_kernel_image, pass_handle),
+                 text    = (visit_kernel_image, pass_handle),
+                 man     = (visit_kernel_image, pass_handle), )
+
+    # figure handling
+    app.add_directive("kernel-figure", KernelFigure)
+    app.add_node(kernel_figure,
+                 html    = (visit_kernel_figure, pass_handle),
+                 latex   = (visit_kernel_figure, pass_handle),
+                 texinfo = (visit_kernel_figure, pass_handle),
+                 text    = (visit_kernel_figure, pass_handle),
+                 man     = (visit_kernel_figure, pass_handle), )
+
+    # render handling
+    app.add_directive('kernel-render', KernelRender)
+    app.add_node(kernel_render,
+                 html    = (visit_kernel_render, pass_handle),
+                 latex   = (visit_kernel_render, pass_handle),
+                 texinfo = (visit_kernel_render, pass_handle),
+                 text    = (visit_kernel_render, pass_handle),
+                 man     = (visit_kernel_render, pass_handle), )
+
+    app.connect('doctree-read', add_kernel_figure_to_std_domain)
+
+    return dict(
+        version = __version__,
+        parallel_read_safe = True,
+        parallel_write_safe = True
+    )
+
+
+def setupTools(app):
+    """
+    Check available build tools and log some *verbose* messages.
+
+    This function is called once, when the builder is initiated.
+    """
+    global dot_cmd, dot_Tpdf, convert_cmd, rsvg_convert_cmd   # pylint: disable=W0603
+    global inkscape_cmd, inkscape_ver_one  # pylint: disable=W0603
+    logger.verbose("kfigure: check installed tools ...")
+
+    dot_cmd = which('dot')
+    convert_cmd = which('convert')
+    rsvg_convert_cmd = which('rsvg-convert')
+    inkscape_cmd = which('inkscape')
+
+    if dot_cmd:
+        logger.verbose("use dot(1) from: " + dot_cmd)
+
+        try:
+            dot_Thelp_list = subprocess.check_output([dot_cmd, '-Thelp'],
+                                    stderr=subprocess.STDOUT)
+        except subprocess.CalledProcessError as err:
+            dot_Thelp_list = err.output
+            pass
+
+        dot_Tpdf_ptn = b'pdf'
+        dot_Tpdf = re.search(dot_Tpdf_ptn, dot_Thelp_list)
+    else:
+        logger.warning(
+            "dot(1) not found, for better output quality install graphviz from https://www.graphviz.org"
+        )
+    if inkscape_cmd:
+        logger.verbose("use inkscape(1) from: " + inkscape_cmd)
+        inkscape_ver = subprocess.check_output([inkscape_cmd, '--version'],
+                                               stderr=subprocess.DEVNULL)
+        ver_one_ptn = b'Inkscape 1'
+        inkscape_ver_one = re.search(ver_one_ptn, inkscape_ver)
+        convert_cmd = None
+        rsvg_convert_cmd = None
+        dot_Tpdf = False
+
+    else:
+        if convert_cmd:
+            logger.verbose("use convert(1) from: " + convert_cmd)
+        else:
+            logger.verbose(
+                "Neither inkscape(1) nor convert(1) found.\n"
+                "For SVG to PDF conversion, install either Inkscape (https://inkscape.org/) (preferred) or\n"
+                "ImageMagick (https://www.imagemagick.org)"
+            )
+
+        if rsvg_convert_cmd:
+            logger.verbose("use rsvg-convert(1) from: " + rsvg_convert_cmd)
+            logger.verbose("use 'dot -Tsvg' and rsvg-convert(1) for DOT -> PDF conversion")
+            dot_Tpdf = False
+        else:
+            logger.verbose(
+                "rsvg-convert(1) not found.\n"
+                "  SVG rendering of convert(1) is done by ImageMagick-native renderer."
+            )
+            if dot_Tpdf:
+                logger.verbose("use 'dot -Tpdf' for DOT -> PDF conversion")
+            else:
+                logger.verbose("use 'dot -Tsvg' and convert(1) for DOT -> PDF conversion")
+
+
+# integrate conversion tools
+# --------------------------
+
+RENDER_MARKUP_EXT = {
+    # The '.ext' must be handled by convert_image(..) function's *in_ext* input.
+    # <name> : <.ext>
+    'DOT' : '.dot',
+    'SVG' : '.svg'
+}
+
+def convert_image(img_node, translator, src_fname=None):
+    """Convert a image node for the builder.
+
+    Different builder prefer different image formats, e.g. *latex* builder
+    prefer PDF while *html* builder prefer SVG format for images.
+
+    This function handles output image formats in dependence of source the
+    format (of the image) and the translator's output format.
+    """
+    app = translator.builder.app
+
+    fname, in_ext = path.splitext(path.basename(img_node['uri']))
+    if src_fname is None:
+        src_fname = path.join(translator.builder.srcdir, img_node['uri'])
+        if not path.exists(src_fname):
+            src_fname = path.join(translator.builder.outdir, img_node['uri'])
+
+    dst_fname = None
+
+    # in kernel builds, use 'make SPHINXOPTS=-v' to see verbose messages
+
+    logger.verbose('assert best format for: ' + img_node['uri'])
+
+    if in_ext == '.dot':
+
+        if not dot_cmd:
+            logger.verbose("dot from graphviz not available / include DOT raw.")
+            img_node.replace_self(file2literal(src_fname))
+
+        elif translator.builder.format == 'latex':
+            dst_fname = path.join(translator.builder.outdir, fname + '.pdf')
+            img_node['uri'] = fname + '.pdf'
+            img_node['candidates'] = {'*': fname + '.pdf'}
+
+
+        elif translator.builder.format == 'html':
+            dst_fname = path.join(
+                translator.builder.outdir,
+                translator.builder.imagedir,
+                fname + '.svg')
+            img_node['uri'] = path.join(
+                translator.builder.imgpath, fname + '.svg')
+            img_node['candidates'] = {
+                '*': path.join(translator.builder.imgpath, fname + '.svg')}
+
+        else:
+            # all other builder formats will include DOT as raw
+            img_node.replace_self(file2literal(src_fname))
+
+    elif in_ext == '.svg':
+
+        if translator.builder.format == 'latex':
+            if not inkscape_cmd and convert_cmd is None:
+                logger.warning(
+                    "no SVG to PDF conversion available / include SVG raw.\n"
+                    "Including large raw SVGs can cause xelatex error.\n"
+                    "Install Inkscape (preferred) or ImageMagick."
+                )
+                img_node.replace_self(file2literal(src_fname))
+            else:
+                dst_fname = path.join(translator.builder.outdir, fname + '.pdf')
+                img_node['uri'] = fname + '.pdf'
+                img_node['candidates'] = {'*': fname + '.pdf'}
+
+    if dst_fname:
+        # the builder needs not to copy one more time, so pop it if exists.
+        translator.builder.images.pop(img_node['uri'], None)
+        _name = dst_fname[len(str(translator.builder.outdir)) + 1:]
+
+        if isNewer(dst_fname, src_fname):
+            logger.verbose("convert: {out}/%s already exists and is newer" % _name)
+
+        else:
+            ok = False
+            mkdir(path.dirname(dst_fname))
+
+            if in_ext == '.dot':
+                logger.verbose('convert DOT to: {out}/' + _name)
+                if translator.builder.format == 'latex' and not dot_Tpdf:
+                    svg_fname = path.join(translator.builder.outdir, fname + '.svg')
+                    ok1 = dot2format(app, src_fname, svg_fname)
+                    ok2 = svg2pdf_by_rsvg(app, svg_fname, dst_fname)
+                    ok = ok1 and ok2
+
+                else:
+                    ok = dot2format(app, src_fname, dst_fname)
+
+            elif in_ext == '.svg':
+                logger.verbose('convert SVG to: {out}/' + _name)
+                ok = svg2pdf(app, src_fname, dst_fname)
+
+            if not ok:
+                img_node.replace_self(file2literal(src_fname))
+
+
+def dot2format(app, dot_fname, out_fname):
+    """Converts DOT file to ``out_fname`` using ``dot(1)``.
+
+    * ``dot_fname`` pathname of the input DOT file, including extension ``.dot``
+    * ``out_fname`` pathname of the output file, including format extension
+
+    The *format extension* depends on the ``dot`` command (see ``man dot``
+    option ``-Txxx``). Normally you will use one of the following extensions:
+
+    - ``.ps`` for PostScript,
+    - ``.svg`` or ``svgz`` for Structured Vector Graphics,
+    - ``.fig`` for XFIG graphics and
+    - ``.png`` or ``gif`` for common bitmap graphics.
+
+    """
+    out_format = path.splitext(out_fname)[1][1:]
+    cmd = [dot_cmd, '-T%s' % out_format, dot_fname]
+    exit_code = 42
+
+    with open(out_fname, "w") as out:
+        exit_code = subprocess.call(cmd, stdout = out)
+        if exit_code != 0:
+            logger.warning(
+                          "Error #%d when calling: %s" % (exit_code, " ".join(cmd)))
+    return bool(exit_code == 0)
+
+def svg2pdf(app, svg_fname, pdf_fname):
+    """Converts SVG to PDF with ``inkscape(1)`` or ``convert(1)`` command.
+
+    Uses ``inkscape(1)`` from Inkscape (https://inkscape.org/) or ``convert(1)``
+    from ImageMagick (https://www.imagemagick.org) for conversion.
+    Returns ``True`` on success and ``False`` if an error occurred.
+
+    * ``svg_fname`` pathname of the input SVG file with extension (``.svg``)
+    * ``pdf_name``  pathname of the output PDF file with extension (``.pdf``)
+
+    """
+    cmd = [convert_cmd, svg_fname, pdf_fname]
+    cmd_name = 'convert(1)'
+
+    if inkscape_cmd:
+        cmd_name = 'inkscape(1)'
+        if inkscape_ver_one:
+            cmd = [inkscape_cmd, '-o', pdf_fname, svg_fname]
+        else:
+            cmd = [inkscape_cmd, '-z', '--export-pdf=%s' % pdf_fname, svg_fname]
+
+    try:
+        warning_msg = subprocess.check_output(cmd, stderr=subprocess.STDOUT)
+        exit_code = 0
+    except subprocess.CalledProcessError as err:
+        warning_msg = err.output
+        exit_code = err.returncode
+        pass
+
+    if exit_code != 0:
+        logger.warning("Error #%d when calling: %s" %
+                            (exit_code, " ".join(cmd)))
+        if warning_msg:
+            logger.warning( "Warning msg from %s: %s" %
+                                (cmd_name, str(warning_msg, 'utf-8')))
+    elif warning_msg:
+        logger.verbose("Warning msg from %s (likely harmless):\n%s" %
+                            (cmd_name, str(warning_msg, 'utf-8')))
+
+    return bool(exit_code == 0)
+
+def svg2pdf_by_rsvg(app, svg_fname, pdf_fname):
+    """Convert SVG to PDF with ``rsvg-convert(1)`` command.
+
+    * ``svg_fname`` pathname of input SVG file, including extension ``.svg``
+    * ``pdf_fname`` pathname of output PDF file, including extension ``.pdf``
+
+    Input SVG file should be the one generated by ``dot2format()``.
+    SVG -> PDF conversion is done by ``rsvg-convert(1)``.
+
+    If ``rsvg-convert(1)`` is unavailable, fall back to ``svg2pdf()``.
+
+    """
+
+    if rsvg_convert_cmd is None:
+        ok = svg2pdf(app, svg_fname, pdf_fname)
+    else:
+        cmd = [rsvg_convert_cmd, '--format=pdf', '-o', pdf_fname, svg_fname]
+        # use stdout and stderr from parent
+        exit_code = subprocess.call(cmd)
+        if exit_code != 0:
+            logger.warning("Error #%d when calling: %s" %
+                                (exit_code, " ".join(cmd)))
+        ok = bool(exit_code == 0)
+
+    return ok
+
+
+# image handling
+# ---------------------
+
+def visit_kernel_image(self, node):    # pylint: disable=W0613
+    """Visitor of the ``kernel_image`` Node.
+
+    Handles the ``image`` child-node with the ``convert_image(...)``.
+    """
+    img_node = node[0]
+    convert_image(img_node, self)
+
+class kernel_image(nodes.image):
+    """Node for ``kernel-image`` directive."""
+    pass
+
+class KernelImage(images.Image):
+    """KernelImage directive
+
+    Earns everything from ``.. image::`` directive, except *remote URI* and
+    *glob* pattern. The KernelImage wraps a image node into a
+    kernel_image node. See ``visit_kernel_image``.
+    """
+
+    def run(self):
+        uri = self.arguments[0]
+        if uri.endswith('.*') or uri.find('://') != -1:
+            raise self.severe(
+                'Error in "%s: %s": glob pattern and remote images are not allowed'
+                % (self.name, uri))
+        result = images.Image.run(self)
+        if len(result) == 2 or isinstance(result[0], nodes.system_message):
+            return result
+        (image_node,) = result
+        # wrap image node into a kernel_image node / see visitors
+        node = kernel_image('', image_node)
+        return [node]
+
+# figure handling
+# ---------------------
+
+def visit_kernel_figure(self, node):   # pylint: disable=W0613
+    """Visitor of the ``kernel_figure`` Node.
+
+    Handles the ``image`` child-node with the ``convert_image(...)``.
+    """
+    img_node = node[0][0]
+    convert_image(img_node, self)
+
+class kernel_figure(nodes.figure):
+    """Node for ``kernel-figure`` directive."""
+
+class KernelFigure(Figure):
+    """KernelImage directive
+
+    Earns everything from ``.. figure::`` directive, except *remote URI* and
+    *glob* pattern.  The KernelFigure wraps a figure node into a kernel_figure
+    node. See ``visit_kernel_figure``.
+    """
+
+    def run(self):
+        uri = self.arguments[0]
+        if uri.endswith('.*') or uri.find('://') != -1:
+            raise self.severe(
+                'Error in "%s: %s":'
+                ' glob pattern and remote images are not allowed'
+                % (self.name, uri))
+        result = Figure.run(self)
+        if len(result) == 2 or isinstance(result[0], nodes.system_message):
+            return result
+        (figure_node,) = result
+        # wrap figure node into a kernel_figure node / see visitors
+        node = kernel_figure('', figure_node)
+        return [node]
+
+
+# render handling
+# ---------------------
+
+def visit_kernel_render(self, node):
+    """Visitor of the ``kernel_render`` Node.
+
+    If rendering tools available, save the markup of the ``literal_block`` child
+    node into a file and replace the ``literal_block`` node with a new created
+    ``image`` node, pointing to the saved markup file. Afterwards, handle the
+    image child-node with the ``convert_image(...)``.
+    """
+    app = self.builder.app
+    srclang = node.get('srclang')
+
+    logger.verbose('visit kernel-render node lang: "%s"' % srclang)
+
+    tmp_ext = RENDER_MARKUP_EXT.get(srclang, None)
+    if tmp_ext is None:
+        logger.warning( 'kernel-render: "%s" unknown / include raw.' % srclang)
+        return
+
+    if not dot_cmd and tmp_ext == '.dot':
+        logger.verbose("dot from graphviz not available / include raw.")
+        return
+
+    literal_block = node[0]
+
+    code      = literal_block.astext()
+    hashobj   = code.encode('utf-8') #  str(node.attributes)
+    fname     = path.join('%s-%s' % (srclang, sha1(hashobj).hexdigest()))
+
+    tmp_fname = path.join(
+        self.builder.outdir, self.builder.imagedir, fname + tmp_ext)
+
+    if not path.isfile(tmp_fname):
+        mkdir(path.dirname(tmp_fname))
+        with open(tmp_fname, "w") as out:
+            out.write(code)
+
+    img_node = nodes.image(node.rawsource, **node.attributes)
+    img_node['uri'] = path.join(self.builder.imgpath, fname + tmp_ext)
+    img_node['candidates'] = {
+        '*': path.join(self.builder.imgpath, fname + tmp_ext)}
+
+    literal_block.replace_self(img_node)
+    convert_image(img_node, self, tmp_fname)
+
+
+class kernel_render(nodes.General, nodes.Inline, nodes.Element):
+    """Node for ``kernel-render`` directive."""
+    pass
+
+class KernelRender(Figure):
+    """KernelRender directive
+
+    Render content by external tool.  Has all the options known from the
+    *figure*  directive, plus option ``caption``.  If ``caption`` has a
+    value, a figure node with the *caption* is inserted. If not, a image node is
+    inserted.
+
+    The KernelRender directive wraps the text of the directive into a
+    literal_block node and wraps it into a kernel_render node. See
+    ``visit_kernel_render``.
+    """
+    has_content = True
+    required_arguments = 1
+    optional_arguments = 0
+    final_argument_whitespace = False
+
+    # earn options from 'figure'
+    option_spec = Figure.option_spec.copy()
+    option_spec['caption'] = directives.unchanged
+
+    def run(self):
+        return [self.build_node()]
+
+    def build_node(self):
+
+        srclang = self.arguments[0].strip()
+        if srclang not in RENDER_MARKUP_EXT.keys():
+            return [self.state_machine.reporter.warning(
+                'Unknown source language "%s", use one of: %s.' % (
+                    srclang, ",".join(RENDER_MARKUP_EXT.keys())),
+                line=self.lineno)]
+
+        code = '\n'.join(self.content)
+        if not code.strip():
+            return [self.state_machine.reporter.warning(
+                'Ignoring "%s" directive without content.' % (
+                    self.name),
+                line=self.lineno)]
+
+        node = kernel_render()
+        node['alt'] = self.options.get('alt','')
+        node['srclang'] = srclang
+        literal_node = nodes.literal_block(code, code)
+        node += literal_node
+
+        caption = self.options.get('caption')
+        if caption:
+            # parse caption's content
+            parsed = nodes.Element()
+            self.state.nested_parse(
+                ViewList([caption], source=''), self.content_offset, parsed)
+            caption_node = nodes.caption(
+                parsed[0].rawsource, '', *parsed[0].children)
+            caption_node.source = parsed[0].source
+            caption_node.line = parsed[0].line
+
+            figure_node = nodes.figure('', node)
+            for k,v in self.options.items():
+                figure_node[k] = v
+            figure_node += caption_node
+
+            node = figure_node
+
+        return node
+
+def add_kernel_figure_to_std_domain(app, doctree):
+    """Add kernel-figure anchors to 'std' domain.
+
+    The ``StandardDomain.process_doc(..)`` method does not know how to resolve
+    the caption (label) of ``kernel-figure`` directive (it only knows about
+    standard nodes, e.g. table, figure etc.). Without any additional handling
+    this will result in a 'undefined label' for kernel-figures.
+
+    This handle adds labels of kernel-figure to the 'std' domain labels.
+    """
+
+    std = app.env.domains["std"]
+    docname = app.env.docname
+    labels = std.data["labels"]
+
+    for name, explicit in doctree.nametypes.items():
+        if not explicit:
+            continue
+        labelid = doctree.nameids[name]
+        if labelid is None:
+            continue
+        node = doctree.ids[labelid]
+
+        if node.tagname == 'kernel_figure':
+            for n in node.next_node():
+                if n.tagname == 'caption':
+                    sectname = clean_astext(n)
+                    # add label to std domain
+                    labels[name] = docname, labelid, sectname
+                    break