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, 911 insertions, 0 deletions

diff --git a/tools/docs/sphinx-build-wrapper b/tools/docs/sphinx-build-wrapper
new file mode 100755
index 000000000..6f1163333
--- /dev/null
+++ b/tools/docs/sphinx-build-wrapper
@@ -0,0 +1,911 @@
+#!/usr/bin/env python3
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (C) 2025 Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
+#
+# pylint: disable=R0902, R0912, R0913, R0914, R0915, R0917, C0103
+#
+# Converted from docs Makefile and parallel-wrapper.sh, both under
+# GPLv2, copyrighted since 2008 by the following authors:
+#
+#    Akira Yokosawa <akiyks@gmail.com>
+#    Arnd Bergmann <arnd@arndb.de>
+#    Breno Leitao <leitao@debian.org>
+#    Carlos Bilbao <carlos.bilbao@amd.com>
+#    Dave Young <dyoung@redhat.com>
+#    Donald Hunter <donald.hunter@gmail.com>
+#    Geert Uytterhoeven <geert+renesas@glider.be>
+#    Jani Nikula <jani.nikula@intel.com>
+#    Jan Stancek <jstancek@redhat.com>
+#    Jonathan Corbet <corbet@lwn.net>
+#    Joshua Clayton <stillcompiling@gmail.com>
+#    Kees Cook <keescook@chromium.org>
+#    Linus Torvalds <torvalds@linux-foundation.org>
+#    Magnus Damm <damm+renesas@opensource.se>
+#    Masahiro Yamada <masahiroy@kernel.org>
+#    Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
+#    Maxim Cournoyer <maxim.cournoyer@gmail.com>
+#    Peter Foley <pefoley2@pefoley.com>
+#    Randy Dunlap <rdunlap@infradead.org>
+#    Rob Herring <robh@kernel.org>
+#    Shuah Khan <shuahkh@osg.samsung.com>
+#    Thorsten Blum <thorsten.blum@toblux.com>
+#    Tomas Winkler <tomas.winkler@intel.com>
+
+
+"""
+Sphinx build wrapper that handles Kernel-specific business rules:
+
+- it gets the Kernel build environment vars;
+- it determines what's the best parallelism;
+- it handles SPHINXDIRS
+
+This tool ensures that MIN_PYTHON_VERSION is satisfied. If version is
+below that, it seeks for a new Python version. If found, it re-runs using
+the newer version.
+"""
+
+import argparse
+import locale
+import os
+import re
+import shlex
+import shutil
+import subprocess
+import sys
+
+from concurrent import futures
+from glob import glob
+
+
+LIB_DIR = "../lib/python"
+SRC_DIR = os.path.dirname(os.path.realpath(__file__))
+
+sys.path.insert(0, os.path.join(SRC_DIR, LIB_DIR))
+
+from kdoc.python_version import PythonVersion
+from kdoc.latex_fonts import LatexFontChecker
+from jobserver import JobserverExec         # pylint: disable=C0413,C0411,E0401
+
+#
+#  Some constants
+#
+VENV_DEFAULT = "sphinx_latest"
+MIN_PYTHON_VERSION = PythonVersion("3.7").version
+PAPER = ["", "a4", "letter"]
+
+TARGETS = {
+    "cleandocs":     { "builder": "clean" },
+    "linkcheckdocs": { "builder": "linkcheck" },
+    "htmldocs":      { "builder": "html" },
+    "epubdocs":      { "builder": "epub",    "out_dir": "epub" },
+    "texinfodocs":   { "builder": "texinfo", "out_dir": "texinfo" },
+    "infodocs":      { "builder": "texinfo", "out_dir": "texinfo" },
+    "mandocs":       { "builder": "man",     "out_dir": "man" },
+    "latexdocs":     { "builder": "latex",   "out_dir": "latex" },
+    "pdfdocs":       { "builder": "latex",   "out_dir": "latex" },
+    "xmldocs":       { "builder": "xml",     "out_dir": "xml" },
+}
+
+
+#
+# SphinxBuilder class
+#
+
+class SphinxBuilder:
+    """
+    Handles a sphinx-build target, adding needed arguments to build
+    with the Kernel.
+    """
+
+    def get_path(self, path, use_cwd=False, abs_path=False):
+        """
+        Ancillary routine to handle paths the right way, as shell does.
+
+        It first expands "~" and "~user". Then, if path is not absolute,
+        join self.srctree. Finally, if requested, convert to abspath.
+        """
+
+        path = os.path.expanduser(path)
+        if not path.startswith("/"):
+            if use_cwd:
+                base = os.getcwd()
+            else:
+                base = self.srctree
+
+            path = os.path.join(base, path)
+
+        if abs_path:
+            return os.path.abspath(path)
+
+        return path
+
+    def check_rust(self, sphinxdirs):
+        """
+        Checks if Rust is enabled
+        """
+        config = os.path.join(self.srctree, ".config")
+
+        if not {'.', 'rust'}.intersection(sphinxdirs):
+            return False
+
+        if not os.path.isfile(config):
+            return False
+
+        re_rust = re.compile(r"CONFIG_RUST=(m|y)")
+
+        try:
+            with open(config, "r", encoding="utf-8") as fp:
+                for line in fp:
+                    if re_rust.match(line):
+                        return True
+
+        except OSError as e:
+            print(f"Failed to open {config}", file=sys.stderr)
+            return False
+
+        return False
+
+    def get_sphinx_extra_opts(self, n_jobs):
+        """
+        Get the number of jobs to be used for docs build passed via command
+        line and desired sphinx verbosity.
+
+        The number of jobs can be on different places:
+
+        1) It can be passed via "-j" argument;
+        2) The SPHINXOPTS="-j8" env var may have "-j";
+        3) if called via GNU make, -j specifies the desired number of jobs.
+           with GNU makefile, this number is available via POSIX jobserver;
+        4) if none of the above is available, it should default to "-jauto",
+           and let sphinx decide the best value.
+        """
+
+        #
+        # SPHINXOPTS env var, if used, contains extra arguments to be used
+        # by sphinx-build time. Among them, it may contain sphinx verbosity
+        # and desired number of parallel jobs.
+        #
+        parser = argparse.ArgumentParser()
+        parser.add_argument('-j', '--jobs', type=int)
+        parser.add_argument('-q', '--quiet', action='store_true')
+        parser.add_argument('-v', '--verbose', default=0, action='count')
+
+        #
+        # Other sphinx-build arguments go as-is, so place them
+        # at self.sphinxopts, using shell parser
+        #
+        sphinxopts = shlex.split(os.environ.get("SPHINXOPTS", ""))
+
+        #
+        # Build a list of sphinx args, honoring verbosity here if specified
+        #
+
+        sphinx_args, self.sphinxopts = parser.parse_known_args(sphinxopts)
+
+        verbose = sphinx_args.verbose
+        if self.verbose:
+            verbose += 1
+
+        if sphinx_args.quiet is True:
+            verbose = 0
+
+        #
+        # If the user explicitly sets "-j" at command line, use it.
+        # Otherwise, pick it from SPHINXOPTS args
+        #
+        if n_jobs:
+            self.n_jobs = n_jobs
+        elif sphinx_args.jobs:
+            self.n_jobs = sphinx_args.jobs
+        else:
+            self.n_jobs = None
+
+        if verbose < 1:
+            self.sphinxopts += ["-q"]
+        else:
+            for i in range(1, sphinx_args.verbose):
+                self.sphinxopts += ["-v"]
+
+    def __init__(self, builddir, venv=None, verbose=False, n_jobs=None,
+                 interactive=None):
+        """Initialize internal variables"""
+        self.venv = venv
+        self.verbose = None
+
+        #
+        # Normal variables passed from Kernel's makefile
+        #
+        self.kernelversion = os.environ.get("KERNELVERSION", "unknown")
+        self.kernelrelease = os.environ.get("KERNELRELEASE", "unknown")
+        self.pdflatex = os.environ.get("PDFLATEX", "xelatex")
+
+        #
+        # Add localversion* to kernelversion if present
+        #
+        for file in glob(os.environ["srctree"] + "/localversion*"):
+            if not file.endswith(".orig"):
+                with open(file, 'r', encoding='utf-8') as f:
+                    text = f.read()
+                    self.kernelversion += text
+
+        #
+        # Kernel main Makefile defines a PYTHON3 variable whose default is
+        # "python3". When set to a different value, it allows running a
+        # diferent version than the default official python3 package.
+        # Several distros package python3xx-sphinx packages with newer
+        # versions of Python and sphinx-build.
+        #
+        # Honor such variable different than default
+        #
+        self.python = os.environ.get("PYTHON3")
+        if self.python == "python3":
+            self.python = None
+
+        if not interactive:
+            self.latexopts = os.environ.get("LATEXOPTS", "-interaction=batchmode -no-shell-escape")
+        else:
+            self.latexopts = os.environ.get("LATEXOPTS", "")
+
+        if not verbose:
+            try:
+                verbose = bool(int(os.environ.get("KBUILD_VERBOSE", 0)))
+            except ValueError:
+                # Handles an eventual case where verbosity is not a number
+                # like KBUILD_VERBOSE=""
+                verbose = False
+
+        if verbose is not None:
+            self.verbose = verbose
+
+        #
+        # Source tree directory. This needs to be at os.environ, as
+        # Sphinx extensions use it
+        #
+        self.srctree = os.environ.get("srctree")
+        if not self.srctree:
+            self.srctree = "."
+            os.environ["srctree"] = self.srctree
+
+        #
+        # Now that we can expand srctree, get other directories as well
+        #
+        self.sphinxbuild = os.environ.get("SPHINXBUILD", "sphinx-build")
+        self.kerneldoc = self.get_path(os.environ.get("KERNELDOC",
+                                                      "tools/docs/kernel-doc"))
+        self.builddir = self.get_path(builddir, use_cwd=True, abs_path=True)
+
+        #
+        # Get directory locations for LaTeX build toolchain
+        #
+        self.pdflatex_cmd = shutil.which(self.pdflatex)
+        self.latexmk_cmd = shutil.which("latexmk")
+
+        self.env = os.environ.copy()
+
+        self.get_sphinx_extra_opts(n_jobs)
+
+        #
+        # If venv command line argument is specified, run Sphinx from venv
+        #
+        if venv:
+            bin_dir = os.path.join(venv, "bin")
+            if not os.path.isfile(os.path.join(bin_dir, "activate")):
+                sys.exit(f"Venv {venv} not found.")
+
+            # "activate" virtual env
+            self.env["PATH"] = bin_dir + ":" + self.env["PATH"]
+            self.env["VIRTUAL_ENV"] = venv
+            if "PYTHONHOME" in self.env:
+                del self.env["PYTHONHOME"]
+            print(f"Setting venv to {venv}")
+
+    def run_sphinx(self, sphinx_build, build_args, *args, **pwargs):
+        """
+        Executes sphinx-build using current python3 command.
+
+        When calling via GNU make, POSIX jobserver is used to tell how
+        many jobs are still available from a job pool. claim all remaining
+        jobs, as we don't want sphinx-build to run in parallel with other
+        jobs.
+
+        Despite that, the user may actually force a different value than
+        the number of available jobs via command line.
+
+        The "with" logic here is used to ensure that the claimed jobs will
+        be freed once subprocess finishes
+        """
+
+        with JobserverExec() as jobserver:
+            if jobserver.claim:
+                #
+                # when GNU make is used, claim available jobs from jobserver
+                #
+                n_jobs = str(jobserver.claim)
+            else:
+                #
+                # Otherwise, let sphinx decide by default
+                #
+                n_jobs = "auto"
+
+            #
+            # If explicitly requested via command line, override default
+            #
+            if self.n_jobs:
+                n_jobs = str(self.n_jobs)
+
+            #
+            # We can't simply call python3 sphinx-build, as OpenSUSE
+            # Tumbleweed uses an ELF binary file (/usr/bin/alts) to switch
+            # between different versions of sphinx-build. So, only call it
+            # prepending "python3.xx" when PYTHON3 variable is not default.
+            #
+            if self.python:
+                cmd = [self.python]
+            else:
+                cmd = []
+
+            cmd += [sphinx_build]
+            cmd += [f"-j{n_jobs}"]
+            cmd += build_args
+            cmd += self.sphinxopts
+
+            if self.verbose:
+                print(" ".join(cmd))
+
+            return subprocess.call(cmd, *args, **pwargs)
+
+    def handle_html(self, css, output_dir):
+        """
+        Extra steps for HTML and epub output.
+
+        For such targets, we need to ensure that CSS will be properly
+        copied to the output _static directory
+        """
+
+        if css:
+            css = os.path.expanduser(css)
+            if not css.startswith("/"):
+                css = os.path.join(self.srctree, css)
+
+            static_dir = os.path.join(output_dir, "_static")
+            os.makedirs(static_dir, exist_ok=True)
+
+            try:
+                shutil.copy2(css, static_dir)
+            except (OSError, IOError) as e:
+                print(f"Warning: Failed to copy CSS: {e}", file=sys.stderr)
+
+    def build_pdf_file(self, latex_cmd, from_dir, path):
+        """Builds a single pdf file using latex_cmd"""
+        try:
+            subprocess.run(latex_cmd + [path],
+                            cwd=from_dir, check=True, env=self.env)
+
+            return True
+        except subprocess.CalledProcessError:
+            return False
+
+    def pdf_parallel_build(self, tex_suffix, latex_cmd, tex_files, n_jobs):
+        """Build PDF files in parallel if possible"""
+        builds = {}
+        build_failed = False
+        max_len = 0
+        has_tex = False
+
+        #
+        # LaTeX PDF error code is almost useless for us:
+        # any warning makes it non-zero. For kernel doc builds it always return
+        # non-zero even when build succeeds. So, let's do the best next thing:
+        # Ignore build errors. At the end, check if all PDF files were built,
+        # printing a summary with the built ones and returning 0 if all of
+        # them were actually built.
+        #
+        with futures.ThreadPoolExecutor(max_workers=n_jobs) as executor:
+            jobs = {}
+
+            for from_dir, pdf_dir, entry in tex_files:
+                name = entry.name
+
+                if not name.endswith(tex_suffix):
+                    continue
+
+                name = name[:-len(tex_suffix)]
+                has_tex = True
+
+                future = executor.submit(self.build_pdf_file, latex_cmd,
+                                         from_dir, entry.path)
+                jobs[future] = (from_dir, pdf_dir, name)
+
+            for future in futures.as_completed(jobs):
+                from_dir, pdf_dir, name = jobs[future]
+
+                pdf_name = name + ".pdf"
+                pdf_from = os.path.join(from_dir, pdf_name)
+                pdf_to = os.path.join(pdf_dir, pdf_name)
+                out_name = os.path.relpath(pdf_to, self.builddir)
+                max_len = max(max_len, len(out_name))
+
+                try:
+                    success = future.result()
+
+                    if success and os.path.exists(pdf_from):
+                        os.rename(pdf_from, pdf_to)
+
+                        #
+                        # if verbose, get the name of built PDF file
+                        #
+                        if self.verbose:
+                           builds[out_name] = "SUCCESS"
+                    else:
+                        builds[out_name] = "FAILED"
+                        build_failed = True
+                except futures.Error as e:
+                    builds[out_name] = f"FAILED ({repr(e)})"
+                    build_failed = True
+
+        #
+        # Handle case where no .tex files were found
+        #
+        if not has_tex:
+            out_name = "LaTeX files"
+            max_len = max(max_len, len(out_name))
+            builds[out_name] = "FAILED: no .tex files were generated"
+            build_failed = True
+
+        return builds, build_failed, max_len
+
+    def handle_pdf(self, output_dirs, deny_vf):
+        """
+        Extra steps for PDF output.
+
+        As PDF is handled via a LaTeX output, after building the .tex file,
+        a new build is needed to create the PDF output from the latex
+        directory.
+        """
+        builds = {}
+        max_len = 0
+        tex_suffix = ".tex"
+        tex_files = []
+
+        #
+        # Since early 2024, Fedora and openSUSE tumbleweed have started
+        # deploying variable-font format of "Noto CJK", causing LaTeX
+        # to break with CJK. Work around it, by denying the variable font
+        # usage during xelatex build by passing the location of a config
+        # file with a deny list.
+        #
+        # See tools/docs/lib/latex_fonts.py for more details.
+        #
+        if deny_vf:
+            deny_vf = os.path.expanduser(deny_vf)
+            if os.path.isdir(deny_vf):
+                self.env["XDG_CONFIG_HOME"] = deny_vf
+
+        for from_dir in output_dirs:
+            pdf_dir = os.path.join(from_dir, "../pdf")
+            os.makedirs(pdf_dir, exist_ok=True)
+
+            if self.latexmk_cmd:
+                latex_cmd = [self.latexmk_cmd, f"-{self.pdflatex}"]
+            else:
+                latex_cmd = [self.pdflatex]
+
+            latex_cmd.extend(shlex.split(self.latexopts))
+
+            # Get a list of tex files to process
+            with os.scandir(from_dir) as it:
+                for entry in it:
+                    if entry.name.endswith(tex_suffix):
+                        tex_files.append((from_dir, pdf_dir, entry))
+
+        #
+        # When using make, this won't be used, as the number of jobs comes
+        # from POSIX jobserver. So, this covers the case where build comes
+        # from command line. On such case, serialize by default, except if
+        # the user explicitly sets the number of jobs.
+        #
+        n_jobs = 1
+
+        # n_jobs is either an integer or "auto". Only use it if it is a number
+        if self.n_jobs:
+            try:
+                n_jobs = int(self.n_jobs)
+            except ValueError:
+                pass
+
+        #
+        # When using make, jobserver.claim is the number of jobs that were
+        # used with "-j" and that aren't used by other make targets
+        #
+        with JobserverExec() as jobserver:
+            n_jobs = 1
+
+            #
+            # Handle the case when a parameter is passed via command line,
+            # using it as default, if jobserver doesn't claim anything
+            #
+            if self.n_jobs:
+                try:
+                    n_jobs = int(self.n_jobs)
+                except ValueError:
+                    pass
+
+            if jobserver.claim:
+                n_jobs = jobserver.claim
+
+            builds, build_failed, max_len = self.pdf_parallel_build(tex_suffix,
+                                                                    latex_cmd,
+                                                                    tex_files,
+                                                                    n_jobs)
+
+        #
+        # In verbose mode, print a summary with the build results per file.
+        # Otherwise, print a single line with all failures, if any.
+        # On both cases, return code 1 indicates build failures,
+        #
+        if self.verbose:
+            msg = "Summary"
+            msg += "\n" + "=" * len(msg)
+            print()
+            print(msg)
+
+            for pdf_name, pdf_file in builds.items():
+                print(f"{pdf_name:<{max_len}}: {pdf_file}")
+
+            print()
+            if build_failed:
+                msg = LatexFontChecker().check()
+                if msg:
+                    print(msg)
+
+                sys.exit("Error: not all PDF files were created.")
+
+        elif build_failed:
+            n_failures = len(builds)
+            failures = ", ".join(builds.keys())
+
+            msg = LatexFontChecker().check()
+            if msg:
+                print(msg)
+
+            sys.exit(f"Error: Can't build {n_failures} PDF file(s): {failures}")
+
+    def handle_info(self, output_dirs):
+        """
+        Extra steps for Info output.
+
+        For texinfo generation, an additional make is needed from the
+        texinfo directory.
+        """
+
+        for output_dir in output_dirs:
+            try:
+                subprocess.run(["make", "info"], cwd=output_dir, check=True)
+            except subprocess.CalledProcessError as e:
+                sys.exit(f"Error generating info docs: {e}")
+
+    def handle_man(self, kerneldoc, docs_dir, src_dir, output_dir):
+        """
+        Create man pages from kernel-doc output
+        """
+
+        re_kernel_doc = re.compile(r"^\.\.\s+kernel-doc::\s*(\S+)")
+
+        if docs_dir == src_dir:
+            #
+            # Pick the entire set of kernel-doc markups from the entire tree
+            #
+            kdoc_files = set([self.srctree])
+        else:
+            kdoc_files = set()
+
+            for fname in glob(os.path.join(src_dir, "**"), recursive=True):
+                if os.path.isfile(fname) and fname.endswith(".rst"):
+                    with open(fname, "r", encoding="utf-8") as in_fp:
+                        data = in_fp.read()
+
+                    for line in data.split("\n"):
+                        match = re_kernel_doc.match(line)
+                        if match:
+                            if os.path.isfile(match.group(1)):
+                                kdoc_files.add(match.group(1))
+
+        if not kdoc_files:
+                sys.exit(f"Directory {src_dir} doesn't contain kernel-doc tags")
+
+        cmd = [ kerneldoc, "-m" ] + sorted(kdoc_files)
+        try:
+            if self.verbose:
+                print(" ".join(cmd))
+
+            result = subprocess.run(cmd, stdout=subprocess.PIPE, text= True)
+
+            if result.returncode:
+                print(f"Warning: kernel-doc returned {result.returncode} warnings")
+
+        except (OSError, ValueError, subprocess.SubprocessError) as e:
+            sys.exit(f"Failed to create man pages for {src_dir}: {repr(e)}")
+
+        fp = None
+        try:
+            for line in result.stdout.split("\n"):
+                if not line.startswith(".TH"):
+                    if fp:
+                        fp.write(line + '\n')
+                    continue
+
+                if fp:
+                    fp.close()
+
+                # Use shlex here, as it handles well parameters with commas
+                args = shlex.split(line)
+                fname = f"{args[1]}.{args[2]}"
+                fname = fname.replace("/", " ")
+                fname = f"{output_dir}/{fname}"
+
+                if self.verbose:
+                    print(f"Creating {fname}")
+                fp = open(fname, "w", encoding="utf-8")
+                fp.write(line + '\n')
+        finally:
+            if fp:
+                fp.close()
+
+    def cleandocs(self, builder):           # pylint: disable=W0613
+        """Remove documentation output directory"""
+        shutil.rmtree(self.builddir, ignore_errors=True)
+
+    def build(self, target, sphinxdirs=None,
+              theme=None, css=None, paper=None, deny_vf=None,
+              skip_sphinx=False):
+        """
+        Build documentation using Sphinx. This is the core function of this
+        module. It prepares all arguments required by sphinx-build.
+        """
+
+        builder = TARGETS[target]["builder"]
+        out_dir = TARGETS[target].get("out_dir", "")
+
+        #
+        # Cleandocs doesn't require sphinx-build
+        #
+        if target == "cleandocs":
+            self.cleandocs(builder)
+            return
+
+        if theme:
+            os.environ["DOCS_THEME"] = theme
+
+        #
+        # Other targets require sphinx-build, so check if it exists
+        #
+        if not skip_sphinx:
+            sphinxbuild = shutil.which(self.sphinxbuild, path=self.env["PATH"])
+            if not sphinxbuild and target != "mandocs":
+                sys.exit(f"Error: {self.sphinxbuild} not found in PATH.\n")
+
+        if target == "pdfdocs":
+            if not self.pdflatex_cmd and not self.latexmk_cmd:
+                sys.exit("Error: pdflatex or latexmk required for PDF generation")
+
+        docs_dir = os.path.abspath(os.path.join(self.srctree, "Documentation"))
+
+        #
+        # Fill in base arguments for Sphinx build
+        #
+        kerneldoc = self.kerneldoc
+        if kerneldoc.startswith(self.srctree):
+            kerneldoc = os.path.relpath(kerneldoc, self.srctree)
+
+        if not sphinxdirs:
+            sphinxdirs = os.environ.get("SPHINXDIRS", ".")
+
+        #
+        # sphinxdirs can be a list or a whitespace-separated string
+        #
+        sphinxdirs_list = []
+        for sphinxdir in sphinxdirs:
+            if isinstance(sphinxdir, list):
+                sphinxdirs_list += sphinxdir
+            else:
+                sphinxdirs_list += sphinxdir.split()
+
+        args = [ "-b", builder, "-c", docs_dir ]
+
+        if builder == "latex":
+            if not paper:
+                paper = PAPER[1]
+
+            args.extend(["-D", f"latex_elements.papersize={paper}paper"])
+
+        rustdoc = self.check_rust(sphinxdirs_list)
+        if rustdoc:
+            args.extend(["-t", "rustdoc"])
+
+        #
+        # The sphinx-build tool has a bug: internally, it tries to set
+        # locale with locale.setlocale(locale.LC_ALL, ''). This causes a
+        # crash if language is not set. Detect and fix it.
+        #
+        try:
+            locale.setlocale(locale.LC_ALL, '')
+        except locale.Error:
+            self.env["LC_ALL"] = "C"
+
+        #
+        # Step 1:  Build each directory in separate.
+        #
+        # This is not the best way of handling it, as cross-references between
+        # them will be broken, but this is what we've been doing since
+        # the beginning.
+        #
+        output_dirs = []
+        for sphinxdir in sphinxdirs_list:
+            src_dir = os.path.join(docs_dir, sphinxdir)
+            doctree_dir = os.path.join(self.builddir, ".doctrees")
+            output_dir = os.path.join(self.builddir, sphinxdir, out_dir)
+
+            #
+            # Make directory names canonical
+            #
+            src_dir = os.path.normpath(src_dir)
+            doctree_dir = os.path.normpath(doctree_dir)
+            output_dir = os.path.normpath(output_dir)
+
+            os.makedirs(doctree_dir, exist_ok=True)
+            os.makedirs(output_dir, exist_ok=True)
+
+            output_dirs.append(output_dir)
+
+            build_args = args + [
+                "-d", doctree_dir,
+                "-D", f"version={self.kernelversion}",
+                "-D", f"release={self.kernelrelease}",
+                "-D", f"kerneldoc_srctree={self.srctree}",
+                src_dir,
+                output_dir,
+            ]
+
+            if target == "mandocs":
+                self.handle_man(kerneldoc, docs_dir, src_dir, output_dir)
+            elif not skip_sphinx:
+                try:
+                    result = self.run_sphinx(sphinxbuild, build_args,
+                                             env=self.env)
+
+                    if result:
+                        sys.exit(f"Build failed: return code: {result}")
+
+                except (OSError, ValueError, subprocess.SubprocessError) as e:
+                    sys.exit(f"Build failed: {repr(e)}")
+
+            #
+            # Ensure that each html/epub output will have needed static files
+            #
+            if target in ["htmldocs", "epubdocs"]:
+                self.handle_html(css, output_dir)
+
+        #
+        # Step 2: Some targets (PDF and info) require an extra step once
+        #         sphinx-build finishes
+        #
+        if target == "pdfdocs":
+            self.handle_pdf(output_dirs, deny_vf)
+        elif target == "infodocs":
+            self.handle_info(output_dirs)
+
+        if rustdoc and target in ["htmldocs", "epubdocs"]:
+            print("Building rust docs")
+            if "MAKE" in self.env:
+                cmd = [self.env["MAKE"]]
+            else:
+                cmd = ["make", "LLVM=1"]
+
+            cmd += [ "rustdoc"]
+            if self.verbose:
+                print(" ".join(cmd))
+
+            try:
+                subprocess.run(cmd, check=True)
+            except subprocess.CalledProcessError as e:
+                print(f"Ignored errors when building rustdoc: {e}. Is RUST enabled?",
+                      file=sys.stderr)
+
+def jobs_type(value):
+    """
+    Handle valid values for -j. Accepts Sphinx "-jauto", plus a number
+    equal or bigger than one.
+    """
+    if value is None:
+        return None
+
+    if value.lower() == 'auto':
+        return value.lower()
+
+    try:
+        if int(value) >= 1:
+            return value
+
+        raise argparse.ArgumentTypeError(f"Minimum jobs is 1, got {value}")
+    except ValueError:
+        raise argparse.ArgumentTypeError(f"Must be 'auto' or positive integer, got {value}")  # pylint: disable=W0707
+
+EPILOG="""
+Besides the command line arguments, several environment variables affect its
+default behavior, meant to be used when called via Kernel Makefile:
+
+- KERNELVERSION:  Kernel major version
+- KERNELRELEASE:  Kernel release
+- KBUILD_VERBOSE: Contains the value of "make V=[0|1] variable.
+                  When V=0 (KBUILD_VERBOSE=0), sets verbose level to "-q".
+- SPHINXBUILD:    Documentation build tool (default: "sphinx-build").
+- SPHINXOPTS:     Extra options pased to SPHINXBUILD
+                  (default: "-j auto" and "-q" if KBUILD_VERBOSE=0).
+                  The "-v" flag can be used to increase verbosity.
+                  If V=0, the first "-v" will drop "-q".
+- PYTHON3:        Python command to run SPHINXBUILD
+- PDFLATEX:       LaTeX PDF engine. (default: "xelatex")
+- LATEXOPTS:      Optional set of command line arguments to the LaTeX engine
+- srctree:        Location of the Kernel root directory (default: ".").
+
+"""
+
+def main():
+    """
+    Main function. The only mandatory argument is the target. If not
+    specified, the other arguments will use default values if not
+    specified at os.environ.
+    """
+    parser = argparse.ArgumentParser(formatter_class=argparse.RawTextHelpFormatter,
+                                     description=__doc__,
+                                     epilog=EPILOG)
+
+    parser.add_argument("target", choices=list(TARGETS.keys()),
+                        help="Documentation target to build")
+    parser.add_argument("--sphinxdirs", nargs="+",
+                        help="Specific directories to build")
+    parser.add_argument("--builddir", default="output",
+                        help="Sphinx configuration file (default: %(default)s)")
+
+    parser.add_argument("--theme", help="Sphinx theme to use")
+
+    parser.add_argument("--css", help="Custom CSS file for HTML/EPUB")
+
+    parser.add_argument("--paper", choices=PAPER, default=PAPER[0],
+                        help="Paper size for LaTeX/PDF output")
+
+    parser.add_argument('--deny-vf',
+                        help="Configuration to deny variable fonts on pdf builds")
+
+    parser.add_argument("-v", "--verbose", action='store_true',
+                        help="place build in verbose mode")
+
+    parser.add_argument('-j', '--jobs', type=jobs_type,
+                        help="Sets number of jobs to use with sphinx-build(default: auto)")
+
+    parser.add_argument('-i', '--interactive', action='store_true',
+                        help="Change latex default to run in interactive mode")
+
+    parser.add_argument('-s', '--skip-sphinx-build', action='store_true',
+                        help="Skip sphinx-build step")
+
+    parser.add_argument("-V", "--venv", nargs='?', const=f'{VENV_DEFAULT}',
+                        default=None,
+                        help=f'If used, run Sphinx from a venv dir (default dir: {VENV_DEFAULT})')
+
+    args = parser.parse_args()
+
+    PythonVersion.check_python(MIN_PYTHON_VERSION, show_alternatives=True,
+                               bail_out=True)
+
+    builder = SphinxBuilder(builddir=args.builddir, venv=args.venv,
+                            verbose=args.verbose, n_jobs=args.jobs,
+                            interactive=args.interactive)
+
+    builder.build(args.target, sphinxdirs=args.sphinxdirs,
+                  theme=args.theme, css=args.css, paper=args.paper,
+                  deny_vf=args.deny_vf,
+                  skip_sphinx=args.skip_sphinx_build)
+
+if __name__ == "__main__":
+    main()