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, 193 insertions, 0 deletions

diff --git a/scripts/headerdep.pl b/scripts/headerdep.pl
new file mode 100755
index 000000000..ebfcbef43
--- /dev/null
+++ b/scripts/headerdep.pl
@@ -0,0 +1,193 @@
+#! /usr/bin/env perl
+# SPDX-License-Identifier: GPL-2.0
+#
+# Detect cycles in the header file dependency graph
+# Vegard Nossum <vegardno@ifi.uio.no>
+#
+
+use strict;
+use warnings;
+
+use Getopt::Long;
+
+my $opt_all;
+my @opt_include;
+my $opt_graph;
+
+&Getopt::Long::Configure(qw(bundling pass_through));
+&GetOptions(
+	help	=> \&help,
+	version	=> \&version,
+
+	all	=> \$opt_all,
+	"I=s"	=> \@opt_include,
+	graph	=> \$opt_graph,
+);
+
+push @opt_include, 'include';
+my %deps = ();
+my %linenos = ();
+
+my @headers = grep { strip($_) } @ARGV;
+
+parse_all(@headers);
+
+if($opt_graph) {
+	graph();
+} else {
+	detect_cycles(@headers);
+}
+
+
+sub help {
+	print "Usage: $0 [options] file...\n";
+	print "\n";
+	print "Options:\n";
+	print "  --all\n";
+	print "  --graph\n";
+	print "\n";
+	print "  -I includedir\n";
+	print "\n";
+	print "To make nice graphs, try:\n";
+	print "  $0 --graph include/linux/kernel.h | dot -Tpng -o graph.png\n";
+	exit;
+}
+
+sub version {
+	print "headerdep version 2\n";
+	exit;
+}
+
+# Get a file name that is relative to our include paths
+sub strip {
+	my $filename = shift;
+
+	for my $i (@opt_include) {
+		my $stripped = $filename;
+		$stripped =~ s/^$i\///;
+
+		return $stripped if $stripped ne $filename;
+	}
+
+	return $filename;
+}
+
+# Search for the file name in the list of include paths
+sub search {
+	my $filename = shift;
+	return $filename if -f $filename;
+
+	for my $i (@opt_include) {
+		my $path = "$i/$filename";
+		return $path if -f $path;
+	}
+	return;
+}
+
+sub parse_all {
+	# Parse all the headers.
+	my @queue = @_;
+	while(@queue) {
+		my $header = pop @queue;
+		next if exists $deps{$header};
+
+		$deps{$header} = [] unless exists $deps{$header};
+
+		my $path = search($header);
+		next unless $path;
+
+		open(my $file, '<', $path) or die($!);
+		chomp(my @lines = <$file>);
+		close($file);
+
+		for my $i (0 .. $#lines) {
+			my $line = $lines[$i];
+			if(my($dep) = ($line =~ m/^#\s*include\s*<(.*?)>/)) {
+				push @queue, $dep;
+				push @{$deps{$header}}, [$i + 1, $dep];
+			}
+		}
+	}
+}
+
+sub print_cycle {
+	# $cycle[n] includes $cycle[n + 1];
+	# $cycle[-1] will be the culprit
+	my $cycle = shift;
+
+	# Adjust the line numbers
+	for my $i (0 .. $#$cycle - 1) {
+		$cycle->[$i]->[0] = $cycle->[$i + 1]->[0];
+	}
+	$cycle->[-1]->[0] = 0;
+
+	my $first = shift @$cycle;
+	my $last = pop @$cycle;
+
+	my $msg = "In file included";
+	printf "%s from %s,\n", $msg, $last->[1] if defined $last;
+
+	for my $header (reverse @$cycle) {
+		printf "%s from %s:%d%s\n",
+			" " x length $msg,
+			$header->[1], $header->[0],
+			$header->[1] eq $last->[1] ? ' <-- here' : '';
+	}
+
+	printf "%s:%d: warning: recursive header inclusion\n",
+		$first->[1], $first->[0];
+}
+
+# Find and print the smallest cycle starting in the specified node.
+sub detect_cycles {
+	my @queue = map { [[0, $_]] } @_;
+	while(@queue) {
+		my $top = pop @queue;
+		my $name = $top->[-1]->[1];
+
+		for my $dep (@{$deps{$name}}) {
+			my $chain = [@$top, [$dep->[0], $dep->[1]]];
+
+			# If the dep already exists in the chain, we have a
+			# cycle...
+			if(grep { $_->[1] eq $dep->[1] } @$top) {
+				print_cycle($chain);
+				next if $opt_all;
+				return;
+			}
+
+			push @queue, $chain;
+		}
+	}
+}
+
+sub mangle {
+	$_ = shift;
+	s/\//__/g;
+	s/\./_/g;
+	s/-/_/g;
+	$_;
+}
+
+# Output dependency graph in GraphViz language.
+sub graph {
+	print "digraph {\n";
+
+	print "\t/* vertices */\n";
+	for my $header (keys %deps) {
+		printf "\t%s [label=\"%s\"];\n",
+			mangle($header), $header;
+	}
+
+	print "\n";
+
+	print "\t/* edges */\n";
+	for my $header (keys %deps) {
+		for my $dep (@{$deps{$header}}) {
+			printf "\t%s -> %s;\n",
+				mangle($header), mangle($dep->[1]);
+		}
+	}
+
+	print "}\n";
+}