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, 174 insertions, 0 deletions

diff --git a/scripts/check-sysctl-docs b/scripts/check-sysctl-docs
new file mode 100755
index 000000000..910fd8a9a
--- /dev/null
+++ b/scripts/check-sysctl-docs
@@ -0,0 +1,174 @@
+#!/usr/bin/env -S gawk -f
+# SPDX-License-Identifier: GPL-2.0
+
+# Script to check sysctl documentation against source files
+#
+# Copyright (c) 2020 Stephen Kitt
+
+# Example invocation:
+#	scripts/check-sysctl-docs -vtable="kernel" \
+#		Documentation/admin-guide/sysctl/kernel.rst \
+#		$(git grep -l register_sysctl)
+#
+# Specify -vdebug=1 to see debugging information
+
+BEGIN {
+	if (!table) {
+	print "Please specify the table to look for using the table variable" > "/dev/stderr"
+	exit 1
+	}
+
+	# Documentation title skiplist
+	skiplist[0] = "^Documentation for"
+	skiplist[1] = "Network core options$"
+	skiplist[2] = "POSIX message queues filesystem$"
+	skiplist[3] = "Configuration options"
+	skiplist[4] = ". /proc/sys/fs"
+	skiplist[5] = "^Introduction$"
+	skiplist[6] = "^seccomp$"
+	skiplist[7] = "^pty$"
+	skiplist[8] = "^firmware_config$"
+	skiplist[9] = "^random$"
+}
+
+# The following globals are used:
+# documented: maps documented entries (each key is an entry)
+# entries: maps ctl_table names and procnames to counts (so
+#          enumerating the subkeys for a given ctl_table lists its
+#          procnames)
+# curtable: the name of the current ctl_table struct
+# curentry: the name of the current proc entry (procname when parsing
+#           a ctl_table, constructed path when parsing a ctl_path)
+
+
+# Remove punctuation from the given value
+function trimpunct(value) {
+	while (value ~ /^["&]/) {
+		value = substr(value, 2)
+	}
+	while (value ~ /[]["&,}]$/) {
+		value = substr(value, 1, length(value) - 1)
+	}
+	return value
+}
+
+# Print the information for the given entry
+function printentry(entry) {
+	seen[entry]++
+	printf "* %s from %s", entry, file[entry]
+	if (documented[entry]) {
+		printf " (documented)"
+	}
+	print ""
+}
+
+
+# Stage 1: build the list of documented entries
+FNR == NR && /^=+$/ {
+	for (i in skiplist) {
+		if (prevline ~ skiplist[i]) {
+			next
+		}
+	}
+
+	# The previous line is a section title, parse it
+	$0 = prevline
+	if (debug) print "Parsing " $0
+	inbrackets = 0
+	for (i = 1; i <= NF; i++) {
+		if (length($i) == 0) {
+			continue
+		}
+		if (!inbrackets && substr($i, 1, 1) == "(") {
+			inbrackets = 1
+		}
+		if (!inbrackets) {
+			token = trimpunct($i)
+			if (length(token) > 0 && token != "and") {
+				if (debug) print trimpunct($i)
+					documented[trimpunct($i)]++
+			}
+		}
+		if (inbrackets && substr($i, length($i), 1) == ")") {
+			inbrackets = 0
+		}
+	}
+}
+
+FNR == NR {
+	prevline = $0
+	next
+}
+
+
+# Stage 2: process each file and find all sysctl tables
+BEGINFILE {
+	delete entries
+	curtable = ""
+	curentry = ""
+	delete vars
+	if (debug) print "Processing file " FILENAME
+}
+
+/^static( const)? struct ctl_table/ {
+	match($0, /static( const)? struct ctl_table ([^][]+)/, tables)
+	curtable = tables[2]
+	if (debug) print "Processing table " curtable
+}
+
+/^};$/ {
+	curtable = ""
+	curentry = ""
+	delete vars
+}
+
+curtable && /\.procname[\t ]*=[\t ]*".+"/ {
+	match($0, /.procname[\t ]*=[\t ]*"([^"]+)"/, names)
+	curentry = names[1]
+	if (debug) print "Adding entry " curentry " to table " curtable
+	entries[curtable][curentry]++
+	file[curentry] = FILENAME
+}
+
+curtable && /UCOUNT_ENTRY.*/ {
+	match($0, /UCOUNT_ENTRY\("([^"]+)"\)/, names)
+	curentry = names[1]
+	if (debug) print "Adding entry " curentry " to table " curtable
+	entries[curtable][curentry]++
+	file[curentry] = FILENAME
+}
+
+/register_sysctl.*/ {
+	match($0, /register_sysctl(|_init|_sz)\("([^"]+)" *, *([^,)]+)/, tables)
+	if (debug) print "Registering table " tables[3] " at " tables[2]
+	if (tables[2] == table) {
+		for (entry in entries[tables[3]]) {
+			printentry(entry)
+		}
+	}
+}
+
+/kmemdup.*/ {
+	match($0, /([^ \t]+) *= *kmemdup\(([^,]+) *,/, names)
+	if (debug) print "Found variable " names[1] " for table " names[2]
+	if (names[2] in entries) {
+		vars[names[1]] = names[2]
+	}
+}
+
+/__register_sysctl_table.*/ {
+	match($0, /__register_sysctl_table\([^,]+, *"([^"]+)" *, *([^,]+)/, tables)
+	if (debug) print "Registering variable table " tables[2] " at " tables[1]
+	if (tables[1] == table && tables[2] in vars) {
+		for (entry in entries[vars[tables[2]]]) {
+			printentry(entry)
+		}
+	}
+}
+
+END {
+	for (entry in documented) {
+		if (!seen[entry])
+			print "No implementation for " entry
+	}
+}