ftrace: Synchronize the initialization of ftrace_opsgrafted

There's some internal state that ftrace_ops needs to have set, but since
it can be declared outside of the ftrace.c code, it calls
ftrace_ops_init() on the ops in every global function. The issue is that
if two tasks call it on the same ops at the same time it is possible to
have the initialization of one corrupt the initialization of the other
call.

Create a ops_mutex to use to synchronize every initialization of the
ftrace_ops. The mutex is taken within checking the ftrace_ops flag that
states it was initializied but the flag is checked again after the mutex
has been taken. Checking first outside the mutex allows it to shortcut
having to take the mutex. But then the check needs to be done again after
the mute is taken in case of races.

Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260902095501.6b59af20@gandalf.local.home
Fixes: f04f24fb7e48d ("ftrace, kprobes: Fix a deadlock on ftrace_regex_lock")
Reported-by: sashiko-bot@kernel.org
Close: https://lore.kernel.org/all/20260829025528.49A831F000E9@smtp.kernel.org/
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 365 insertions, 0 deletions

diff --git a/Documentation/sphinx/rstFlatTable.py b/Documentation/sphinx/rstFlatTable.py
new file mode 100755
index 000000000..3d19569e5
--- /dev/null
+++ b/Documentation/sphinx/rstFlatTable.py
@@ -0,0 +1,365 @@
+#!/usr/bin/env python3
+# -*- coding: utf-8; mode: python -*-
+# SPDX-License-Identifier: GPL-2.0
+# pylint: disable=C0330, R0903, R0912
+
+"""
+    flat-table
+    ~~~~~~~~~~
+
+    Implementation of the ``flat-table`` reST-directive.
+
+    :copyright:  Copyright (C) 2016  Markus Heiser
+    :license:    GPL Version 2, June 1991 see linux/COPYING for details.
+
+    The ``flat-table`` (:py:class:`FlatTable`) is a double-stage list similar to
+    the ``list-table`` with some additional features:
+
+    * *column-span*: with the role ``cspan`` a cell can be extended through
+      additional columns
+
+    * *row-span*: with the role ``rspan`` a cell can be extended through
+      additional rows
+
+    * *auto span* rightmost cell of a table row over the missing cells on the
+      right side of that table-row.  With Option ``:fill-cells:`` this behavior
+      can be changed from *auto span* to *auto fill*, which automatically inserts
+      (empty) cells instead of spanning the last cell.
+
+    Options:
+
+    * header-rows:   [int] count of header rows
+    * stub-columns:  [int] count of stub columns
+    * widths:        [[int] [int] ... ] widths of columns
+    * fill-cells:    instead of autospann missing cells, insert missing cells
+
+    roles:
+
+    * cspan: [int] additionale columns (*morecols*)
+    * rspan: [int] additionale rows (*morerows*)
+"""
+
+# ==============================================================================
+# imports
+# ==============================================================================
+
+from docutils import nodes
+from docutils.parsers.rst import directives, roles
+from docutils.parsers.rst.directives.tables import Table
+from docutils.utils import SystemMessagePropagation
+
+# ==============================================================================
+# common globals
+# ==============================================================================
+
+__version__  = '1.0'
+
+# ==============================================================================
+def setup(app):
+# ==============================================================================
+
+    app.add_directive("flat-table", FlatTable)
+    roles.register_local_role('cspan', c_span)
+    roles.register_local_role('rspan', r_span)
+
+    return dict(
+        version = __version__,
+        parallel_read_safe = True,
+        parallel_write_safe = True
+    )
+
+# ==============================================================================
+def c_span(name, rawtext, text, lineno, inliner, options=None, content=None):
+# ==============================================================================
+    # pylint: disable=W0613
+
+    options  = options if options is not None else {}
+    content  = content if content is not None else []
+    nodelist = [colSpan(span=int(text))]
+    msglist  = []
+    return nodelist, msglist
+
+# ==============================================================================
+def r_span(name, rawtext, text, lineno, inliner, options=None, content=None):
+# ==============================================================================
+    # pylint: disable=W0613
+
+    options  = options if options is not None else {}
+    content  = content if content is not None else []
+    nodelist = [rowSpan(span=int(text))]
+    msglist  = []
+    return nodelist, msglist
+
+
+# ==============================================================================
+class rowSpan(nodes.General, nodes.Element): pass # pylint: disable=C0103,C0321
+class colSpan(nodes.General, nodes.Element): pass # pylint: disable=C0103,C0321
+# ==============================================================================
+
+# ==============================================================================
+class FlatTable(Table):
+# ==============================================================================
+
+    """FlatTable (``flat-table``) directive"""
+
+    option_spec = {
+        'name': directives.unchanged
+        , 'class': directives.class_option
+        , 'header-rows': directives.nonnegative_int
+        , 'stub-columns': directives.nonnegative_int
+        , 'widths': directives.positive_int_list
+        , 'fill-cells' : directives.flag }
+
+    def run(self):
+
+        if not self.content:
+            error = self.state_machine.reporter.error(
+                'The "%s" directive is empty; content required.' % self.name,
+                nodes.literal_block(self.block_text, self.block_text),
+                line=self.lineno)
+            return [error]
+
+        title, messages = self.make_title()
+        node = nodes.Element()          # anonymous container for parsing
+        self.state.nested_parse(self.content, self.content_offset, node)
+
+        tableBuilder = ListTableBuilder(self)
+        tableBuilder.parseFlatTableNode(node)
+        tableNode = tableBuilder.buildTableNode()
+        # SDK.CONSOLE()  # print --> tableNode.asdom().toprettyxml()
+        if title:
+            tableNode.insert(0, title)
+        return [tableNode] + messages
+
+
+# ==============================================================================
+class ListTableBuilder(object):
+# ==============================================================================
+
+    """Builds a table from a double-stage list"""
+
+    def __init__(self, directive):
+        self.directive = directive
+        self.rows      = []
+        self.max_cols  = 0
+
+    def buildTableNode(self):
+
+        colwidths    = self.directive.get_column_widths(self.max_cols)
+        if isinstance(colwidths, tuple):
+            # Since docutils 0.13, get_column_widths returns a (widths,
+            # colwidths) tuple, where widths is a string (i.e. 'auto').
+            # See https://sourceforge.net/p/docutils/patches/120/.
+            colwidths = colwidths[1]
+        stub_columns = self.directive.options.get('stub-columns', 0)
+        header_rows  = self.directive.options.get('header-rows', 0)
+
+        table = nodes.table()
+        tgroup = nodes.tgroup(cols=len(colwidths))
+        table += tgroup
+
+
+        for colwidth in colwidths:
+            colspec = nodes.colspec(colwidth=colwidth)
+            # FIXME: It seems, that the stub method only works well in the
+            # absence of rowspan (observed by the html builder, the docutils-xml
+            # build seems OK).  This is not extraordinary, because there exists
+            # no table directive (except *this* flat-table) which allows to
+            # define coexistent of rowspan and stubs (there was no use-case
+            # before flat-table). This should be reviewed (later).
+            if stub_columns:
+                colspec.attributes['stub'] = 1
+                stub_columns -= 1
+            tgroup += colspec
+        stub_columns = self.directive.options.get('stub-columns', 0)
+
+        if header_rows:
+            thead = nodes.thead()
+            tgroup += thead
+            for row in self.rows[:header_rows]:
+                thead += self.buildTableRowNode(row)
+
+        tbody = nodes.tbody()
+        tgroup += tbody
+
+        for row in self.rows[header_rows:]:
+            tbody += self.buildTableRowNode(row)
+        return table
+
+    def buildTableRowNode(self, row_data, classes=None):
+        classes = [] if classes is None else classes
+        row = nodes.row()
+        for cell in row_data:
+            if cell is None:
+                continue
+            cspan, rspan, cellElements = cell
+
+            attributes = {"classes" : classes}
+            if rspan:
+                attributes['morerows'] = rspan
+            if cspan:
+                attributes['morecols'] = cspan
+            entry = nodes.entry(**attributes)
+            entry.extend(cellElements)
+            row += entry
+        return row
+
+    def raiseError(self, msg):
+        error =  self.directive.state_machine.reporter.error(
+            msg
+            , nodes.literal_block(self.directive.block_text
+                                  , self.directive.block_text)
+            , line = self.directive.lineno )
+        raise SystemMessagePropagation(error)
+
+    def parseFlatTableNode(self, node):
+        """parses the node from a :py:class:`FlatTable` directive's body"""
+
+        if len(node) != 1 or not isinstance(node[0], nodes.bullet_list):
+            self.raiseError(
+                'Error parsing content block for the "%s" directive: '
+                'exactly one bullet list expected.' % self.directive.name )
+
+        for rowNum, rowItem in enumerate(node[0]):
+            row = self.parseRowItem(rowItem, rowNum)
+            self.rows.append(row)
+        self.roundOffTableDefinition()
+
+    def roundOffTableDefinition(self):
+        """Round off the table definition.
+
+        This method rounds off the table definition in :py:member:`rows`.
+
+        * This method inserts the needed ``None`` values for the missing cells
+        arising from spanning cells over rows and/or columns.
+
+        * recount the :py:member:`max_cols`
+
+        * Autospan or fill (option ``fill-cells``) missing cells on the right
+          side of the table-row
+        """
+
+        y = 0
+        while y < len(self.rows):
+            x = 0
+
+            while x < len(self.rows[y]):
+                cell = self.rows[y][x]
+                if cell is None:
+                    x += 1
+                    continue
+                cspan, rspan = cell[:2]
+                # handle colspan in current row
+                for c in range(cspan):
+                    try:
+                        self.rows[y].insert(x+c+1, None)
+                    except: # pylint: disable=W0702
+                        # the user sets ambiguous rowspans
+                        pass # SDK.CONSOLE()
+                # handle colspan in spanned rows
+                for r in range(rspan):
+                    for c in range(cspan + 1):
+                        try:
+                            self.rows[y+r+1].insert(x+c, None)
+                        except: # pylint: disable=W0702
+                            # the user sets ambiguous rowspans
+                            pass # SDK.CONSOLE()
+                x += 1
+            y += 1
+
+        # Insert the missing cells on the right side. For this, first
+        # re-calculate the max columns.
+
+        for row in self.rows:
+            if self.max_cols < len(row):
+                self.max_cols = len(row)
+
+        # fill with empty cells or cellspan?
+
+        fill_cells = False
+        if 'fill-cells' in self.directive.options:
+            fill_cells = True
+
+        for row in self.rows:
+            x =  self.max_cols - len(row)
+            if x and not fill_cells:
+                if row[-1] is None:
+                    row.append( ( x - 1, 0, []) )
+                else:
+                    cspan, rspan, content = row[-1]
+                    row[-1] = (cspan + x, rspan, content)
+            elif x and fill_cells:
+                for i in range(x):
+                    row.append( (0, 0, nodes.comment()) )
+
+    def pprint(self):
+        # for debugging
+        retVal = "[   "
+        for row in self.rows:
+            retVal += "[ "
+            for col in row:
+                if col is None:
+                    retVal += ('%r' % col)
+                    retVal += "\n    , "
+                else:
+                    content = col[2][0].astext()
+                    if len (content) > 30:
+                        content = content[:30] + "..."
+                    retVal += ('(cspan=%s, rspan=%s, %r)'
+                               % (col[0], col[1], content))
+                    retVal += "]\n    , "
+            retVal = retVal[:-2]
+            retVal += "]\n  , "
+        retVal = retVal[:-2]
+        return retVal + "]"
+
+    def parseRowItem(self, rowItem, rowNum):
+        row = []
+        childNo = 0
+        error   = False
+        cell    = None
+        target  = None
+
+        for child in rowItem:
+            if (isinstance(child , nodes.comment)
+                or isinstance(child, nodes.system_message)):
+                pass
+            elif isinstance(child , nodes.target):
+                target = child
+            elif isinstance(child, nodes.bullet_list):
+                childNo += 1
+                cell = child
+            else:
+                error = True
+                break
+
+        if childNo != 1 or error:
+            self.raiseError(
+                'Error parsing content block for the "%s" directive: '
+                'two-level bullet list expected, but row %s does not '
+                'contain a second-level bullet list.'
+                % (self.directive.name, rowNum + 1))
+
+        for cellItem in cell:
+            cspan, rspan, cellElements = self.parseCellItem(cellItem)
+            if target is not None:
+                cellElements.insert(0, target)
+            row.append( (cspan, rspan, cellElements) )
+        return row
+
+    def parseCellItem(self, cellItem):
+        # search and remove cspan, rspan colspec from the first element in
+        # this listItem (field).
+        cspan = rspan = 0
+        if not len(cellItem):
+            return cspan, rspan, []
+        for elem in cellItem[0]:
+            if isinstance(elem, colSpan):
+                cspan = elem.get("span")
+                elem.parent.remove(elem)
+                continue
+            if isinstance(elem, rowSpan):
+                rspan = elem.get("span")
+                elem.parent.remove(elem)
+                continue
+        return cspan, rspan, cellItem[:]