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, 527 insertions, 0 deletions

diff --git a/Documentation/sphinx/kernel_include.py b/Documentation/sphinx/kernel_include.py
new file mode 100755
index 000000000..626762ff6
--- /dev/null
+++ b/Documentation/sphinx/kernel_include.py
@@ -0,0 +1,527 @@
+#!/usr/bin/env python3
+# SPDX-License-Identifier: GPL-2.0
+# pylint: disable=R0903, R0912, R0914, R0915, C0209,W0707
+
+
+"""
+Implementation of the ``kernel-include`` reST-directive.
+
+:copyright:  Copyright (C) 2016  Markus Heiser
+:license:    GPL Version 2, June 1991 see linux/COPYING for details.
+
+The ``kernel-include`` reST-directive is a replacement for the ``include``
+directive. The ``kernel-include`` directive expand environment variables in
+the path name and allows to include files from arbitrary locations.
+
+.. hint::
+
+    Including files from arbitrary locations (e.g. from ``/etc``) is a
+    security risk for builders. This is why the ``include`` directive from
+    docutils *prohibit* pathnames pointing to locations *above* the filesystem
+    tree where the reST document with the include directive is placed.
+
+Substrings of the form $name or ${name} are replaced by the value of
+environment variable name. Malformed variable names and references to
+non-existing variables are left unchanged.
+
+**Supported Sphinx Include Options**:
+
+:param literal:
+    If present, the included file is inserted as a literal block.
+
+:param code:
+    Specify the language for syntax highlighting (e.g., 'c', 'python').
+
+:param encoding:
+    Specify the encoding of the included file (default: 'utf-8').
+
+:param tab-width:
+    Specify the number of spaces that a tab represents.
+
+:param start-line:
+    Line number at which to start including the file (1-based).
+
+:param end-line:
+    Line number at which to stop including the file (inclusive).
+
+:param start-after:
+    Include lines after the first line matching this text.
+
+:param end-before:
+    Include lines before the first line matching this text.
+
+:param number-lines:
+    Number the included lines (integer specifies start number).
+    Only effective with 'literal' or 'code' options.
+
+:param class:
+    Specify HTML class attribute for the included content.
+
+**Kernel-specific Extensions**:
+
+:param generate-cross-refs:
+    If present, instead of directly including the file, it calls
+    ParseDataStructs() to convert C data structures into cross-references
+    that link to comprehensive documentation in other ReST files.
+
+:param exception-file:
+    (Used with generate-cross-refs)
+
+    Path to a file containing rules for handling special cases:
+    - Ignore specific C data structures
+    - Use alternative reference names
+    - Specify different reference types
+
+:param warn-broken:
+    (Used with generate-cross-refs)
+
+    Enables warnings when auto-generated cross-references don't point to
+    existing documentation targets.
+"""
+
+# ==============================================================================
+# imports
+# ==============================================================================
+
+import os.path
+import re
+import sys
+
+from difflib import get_close_matches
+
+from docutils import io, nodes, statemachine
+from docutils.statemachine import ViewList
+from docutils.parsers.rst import Directive, directives
+from docutils.parsers.rst.directives.body import CodeBlock, NumberLines
+
+from sphinx.util import logging
+
+srctree = os.path.abspath(os.environ["srctree"])
+sys.path.insert(0, os.path.join(srctree, "tools/lib/python"))
+
+from kdoc.parse_data_structs import ParseDataStructs
+
+__version__ = "1.0"
+logger = logging.getLogger(__name__)
+
+RE_DOMAIN_REF = re.compile(r'\\ :(ref|c:type|c:func):`([^<`]+)(?:<([^>]+)>)?`\\')
+RE_SIMPLE_REF = re.compile(r'`([^`]+)`')
+RE_LINENO_REF = re.compile(r'^\s*-\s+LINENO_(\d+):\s+(.*)')
+RE_SPLIT_DOMAIN = re.compile(r"(.*)\.(.*)")
+
+def ErrorString(exc):  # Shamelessly stolen from docutils
+    return f'{exc.__class__.__name}: {exc}'
+
+
+# ==============================================================================
+class KernelInclude(Directive):
+    """
+    KernelInclude (``kernel-include``) directive
+
+    Most of the stuff here came from Include directive defined at:
+        docutils/parsers/rst/directives/misc.py
+
+    Yet, overriding the class don't has any benefits: the original class
+    only have run() and argument list. Not all of them are implemented,
+    when checked against latest Sphinx version, as with time more arguments
+    were added.
+
+    So, keep its own list of supported arguments
+    """
+
+    required_arguments = 1
+    optional_arguments = 0
+    final_argument_whitespace = True
+    option_spec = {
+        'literal': directives.flag,
+        'code': directives.unchanged,
+        'encoding': directives.encoding,
+        'tab-width': int,
+        'start-line': int,
+        'end-line': int,
+        'start-after': directives.unchanged_required,
+        'end-before': directives.unchanged_required,
+        # ignored except for 'literal' or 'code':
+        'number-lines': directives.unchanged,  # integer or None
+        'class': directives.class_option,
+
+        # Arguments that aren't from Sphinx Include directive
+        'generate-cross-refs': directives.flag,
+        'warn-broken': directives.flag,
+        'toc': directives.flag,
+        'exception-file': directives.unchanged,
+    }
+
+    def read_rawtext(self, path, encoding):
+            """Read and process file content with error handling"""
+            try:
+                self.state.document.settings.record_dependencies.add(path)
+                include_file = io.FileInput(source_path=path,
+                                            encoding=encoding,
+                                            error_handler=self.state.document.settings.input_encoding_error_handler)
+            except UnicodeEncodeError:
+                raise self.severe('Problems with directive path:\n'
+                                'Cannot encode input file path "%s" '
+                                '(wrong locale?).' % path)
+            except IOError as error:
+                raise self.severe('Problems with directive path:\n%s.' % ErrorString(error))
+
+            try:
+                return include_file.read()
+            except UnicodeError as error:
+                raise self.severe('Problem with directive:\n%s' % ErrorString(error))
+
+    def apply_range(self, rawtext):
+        """
+        Handles start-line, end-line, start-after and end-before parameters
+        """
+
+        # Get to-be-included content
+        startline = self.options.get('start-line', None)
+        endline = self.options.get('end-line', None)
+        try:
+            if startline or (endline is not None):
+                lines = rawtext.splitlines()
+                rawtext = '\n'.join(lines[startline:endline])
+        except UnicodeError as error:
+            raise self.severe(f'Problem with "{self.name}" directive:\n'
+                              + io.error_string(error))
+        # start-after/end-before: no restrictions on newlines in match-text,
+        # and no restrictions on matching inside lines vs. line boundaries
+        after_text = self.options.get("start-after", None)
+        if after_text:
+            # skip content in rawtext before *and incl.* a matching text
+            after_index = rawtext.find(after_text)
+            if after_index < 0:
+                raise self.severe('Problem with "start-after" option of "%s" '
+                                  "directive:\nText not found." % self.name)
+            rawtext = rawtext[after_index + len(after_text) :]
+        before_text = self.options.get("end-before", None)
+        if before_text:
+            # skip content in rawtext after *and incl.* a matching text
+            before_index = rawtext.find(before_text)
+            if before_index < 0:
+                raise self.severe('Problem with "end-before" option of "%s" '
+                                  "directive:\nText not found." % self.name)
+            rawtext = rawtext[:before_index]
+
+        return rawtext
+
+    def xref_text(self, env, path, tab_width):
+        """
+        Read and add contents from a C file parsed to have cross references.
+
+        There are two types of supported output here:
+        - A C source code with cross-references;
+        - a TOC table containing cross references.
+        """
+        parser = ParseDataStructs()
+
+        if 'exception-file' in self.options:
+            source_dir = os.path.dirname(os.path.abspath(
+                self.state_machine.input_lines.source(
+                    self.lineno - self.state_machine.input_offset - 1)))
+            exceptions_file = os.path.join(source_dir, self.options['exception-file'])
+        else:
+            exceptions_file = None
+
+        parser.parse_file(path, exceptions_file)
+
+        # Store references on a symbol dict to be used at check time
+        if 'warn-broken' in self.options:
+            env._xref_files.add(path)
+
+        if "toc" not in self.options:
+
+            rawtext = ".. parsed-literal::\n\n" + parser.gen_output()
+            self.apply_range(rawtext)
+
+            include_lines = statemachine.string2lines(rawtext, tab_width,
+                                                      convert_whitespace=True)
+
+            # Sphinx always blame the ".. <directive>", so placing
+            # line numbers here won't make any difference
+
+            self.state_machine.insert_input(include_lines, path)
+            return []
+
+        # TOC output is a ReST file, not a literal. So, we can add line
+        # numbers
+
+        startline = self.options.get('start-line', None)
+        endline = self.options.get('end-line', None)
+
+        relpath = os.path.relpath(path, srctree)
+
+        result = ViewList()
+        for line in parser.gen_toc().split("\n"):
+            match = RE_LINENO_REF.match(line)
+            if not match:
+                result.append(line, path)
+                continue
+
+            ln, ref = match.groups()
+            ln = int(ln)
+
+            # Filter line range if needed
+            if startline and (ln < startline):
+                continue
+
+            if endline and (ln > endline):
+                continue
+
+            # Sphinx numerates starting with zero, but text editors
+            # and other tools start from one
+            realln = ln + 1
+            result.append(f"- {ref}: {relpath}#{realln}", path, ln)
+
+        self.state_machine.insert_input(result, path)
+
+        return []
+
+    def literal(self, path, tab_width, rawtext):
+        """Output a literal block"""
+
+        # Convert tabs to spaces, if `tab_width` is positive.
+        if tab_width >= 0:
+            text = rawtext.expandtabs(tab_width)
+        else:
+            text = rawtext
+        literal_block = nodes.literal_block(rawtext, source=path,
+                                            classes=self.options.get("class", []))
+        literal_block.line = 1
+        self.add_name(literal_block)
+        if "number-lines" in self.options:
+            try:
+                startline = int(self.options["number-lines"] or 1)
+            except ValueError:
+                raise self.error(":number-lines: with non-integer start value")
+            endline = startline + len(include_lines)
+            if text.endswith("\n"):
+                text = text[:-1]
+            tokens = NumberLines([([], text)], startline, endline)
+            for classes, value in tokens:
+                if classes:
+                    literal_block += nodes.inline(value, value,
+                                                    classes=classes)
+                else:
+                    literal_block += nodes.Text(value, value)
+        else:
+            literal_block += nodes.Text(text, text)
+        return [literal_block]
+
+    def code(self, path, tab_width):
+        """Output a code block"""
+
+        include_lines = statemachine.string2lines(rawtext, tab_width,
+                                                  convert_whitespace=True)
+
+        self.options["source"] = path
+        codeblock = CodeBlock(self.name,
+                                [self.options.pop("code")],  # arguments
+                                self.options,
+                                include_lines,
+                                self.lineno,
+                                self.content_offset,
+                                self.block_text,
+                                self.state,
+                                self.state_machine)
+        return codeblock.run()
+
+    def run(self):
+        """Include a file as part of the content of this reST file."""
+        env = self.state.document.settings.env
+
+        #
+        # The include logic accepts only patches relative to the
+        # Kernel source tree.  The logic does check it to prevent
+        # directory traverse issues.
+        #
+
+        srctree = os.path.abspath(os.environ["srctree"])
+
+        path = os.path.expandvars(self.arguments[0])
+        src_path = os.path.join(srctree, path)
+
+        if os.path.isfile(src_path):
+            base = srctree
+            path = src_path
+        else:
+            raise self.warning(f'File "%s" doesn\'t exist', path)
+
+        abs_base = os.path.abspath(base)
+        abs_full_path = os.path.abspath(os.path.join(base, path))
+
+        try:
+            if os.path.commonpath([abs_full_path, abs_base]) != abs_base:
+                raise self.severe('Problems with "%s" directive, prohibited path: %s' %
+                                  (self.name, path))
+        except ValueError:
+            # Paths don't have the same drive (Windows) or other incompatibility
+            raise self.severe('Problems with "%s" directive, invalid path: %s' %
+                            (self.name, path))
+
+        self.arguments[0] = path
+
+        #
+        # Add path location to Sphinx dependencies to ensure proper cache
+        # invalidation check.
+        #
+
+        env.note_dependency(os.path.abspath(path))
+
+        if not self.state.document.settings.file_insertion_enabled:
+            raise self.warning('"%s" directive disabled.' % self.name)
+        source = self.state_machine.input_lines.source(self.lineno -
+                                                       self.state_machine.input_offset - 1)
+        source_dir = os.path.dirname(os.path.abspath(source))
+        path = directives.path(self.arguments[0])
+        if path.startswith("<") and path.endswith(">"):
+            path = os.path.join(self.standard_include_path, path[1:-1])
+        path = os.path.normpath(os.path.join(source_dir, path))
+
+        # HINT: this is the only line I had to change / commented out:
+        # path = utils.relative_path(None, path)
+
+        encoding = self.options.get("encoding",
+                                    self.state.document.settings.input_encoding)
+        tab_width = self.options.get("tab-width",
+                                     self.state.document.settings.tab_width)
+
+        # Get optional arguments to related to cross-references generation
+        if "generate-cross-refs" in self.options:
+            return self.xref_text(env, path, tab_width)
+
+        rawtext = self.read_rawtext(path, encoding)
+        rawtext = self.apply_range(rawtext)
+
+        if "code" in self.options:
+            return self.code(path, tab_width, rawtext)
+
+        return self.literal(path, tab_width, rawtext)
+
+# ==============================================================================
+
+reported = set()
+DOMAIN_INFO = {}
+all_refs = {}
+
+def fill_domain_info(env):
+    """
+    Get supported reference types for each Sphinx domain and C namespaces
+    """
+    if DOMAIN_INFO:
+        return
+
+    for domain_name, domain_instance in env.domains.items():
+        try:
+            object_types = list(domain_instance.object_types.keys())
+            DOMAIN_INFO[domain_name] = object_types
+        except AttributeError:
+            # Ignore domains that we can't retrieve object types, if any
+            pass
+
+    for domain in DOMAIN_INFO.keys():
+        domain_obj = env.get_domain(domain)
+        for name, dispname, objtype, docname, anchor, priority in domain_obj.get_objects():
+            ref_name = name.lower()
+
+            if domain == "c":
+                if '.' in ref_name:
+                    ref_name = ref_name.split(".")[-1]
+
+            if not ref_name in all_refs:
+                all_refs[ref_name] = []
+
+            all_refs[ref_name].append(f"\t{domain}:{objtype}:`{name}` (from {docname})")
+
+def get_suggestions(app, env, node,
+                    original_target, original_domain, original_reftype):
+    """Check if target exists in the other domain or with different reftypes."""
+    original_target = original_target.lower()
+
+    # Remove namespace if present
+    if original_domain == "c":
+        if '.' in original_target:
+            original_target = original_target.split(".")[-1]
+
+    suggestions = []
+
+    # If name exists, propose exact name match on different domains
+    if original_target in all_refs:
+        return all_refs[original_target]
+
+    # If not found, get a close match, using difflib.
+    # Such method is based on Ratcliff-Obershelp Algorithm, which seeks
+    # for a close match within a certain distance. We're using the defaults
+    # here, e.g. cutoff=0.6, proposing 3 alternatives
+    matches = get_close_matches(original_target, all_refs.keys())
+    for match in matches:
+        suggestions += all_refs[match]
+
+    return suggestions
+
+def check_missing_refs(app, env, node, contnode):
+    """Check broken refs for the files it creates xrefs"""
+    if not node.source:
+        return None
+
+    try:
+        xref_files = env._xref_files
+    except AttributeError:
+        logger.critical("FATAL: _xref_files not initialized!")
+        raise
+
+    # Only show missing references for kernel-include reference-parsed files
+    if node.source not in xref_files:
+        return None
+
+    fill_domain_info(env)
+
+    target = node.get('reftarget', '')
+    domain = node.get('refdomain', 'std')
+    reftype = node.get('reftype', '')
+
+    msg = f"Invalid xref: {domain}:{reftype}:`{target}`"
+
+    # Don't duplicate warnings
+    data = (node.source, msg)
+    if data in reported:
+        return None
+    reported.add(data)
+
+    suggestions = get_suggestions(app, env, node, target, domain, reftype)
+    if suggestions:
+        msg += ". Possible alternatives:\n" + '\n'.join(suggestions)
+
+    logger.warning(msg, location=node, type='ref', subtype='missing')
+
+    return None
+
+def merge_xref_info(app, env, docnames, other):
+    """
+    As each process modify env._xref_files, we need to merge them back.
+    """
+    if not hasattr(other, "_xref_files"):
+        return
+    env._xref_files.update(getattr(other, "_xref_files", set()))
+
+def init_xref_docs(app, env, docnames):
+    """Initialize a list of files that we're generating cross references¨"""
+    app.env._xref_files = set()
+
+# ==============================================================================
+
+def setup(app):
+    """Setup Sphinx exension"""
+
+    app.connect("env-before-read-docs", init_xref_docs)
+    app.connect("env-merge-info", merge_xref_info)
+    app.add_directive("kernel-include", KernelInclude)
+    app.connect("missing-reference", check_missing_refs)
+
+    return {
+        "version": __version__,
+        "parallel_read_safe": True,
+        "parallel_write_safe": True,
+    }