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, 134 insertions, 0 deletions

diff --git a/tools/perf/tests/subcmd-help.c b/tools/perf/tests/subcmd-help.c
new file mode 100644
index 000000000..9da96a16f
--- /dev/null
+++ b/tools/perf/tests/subcmd-help.c
@@ -0,0 +1,134 @@
+// SPDX-License-Identifier: GPL-2.0
+#include "tests.h"
+#include <linux/compiler.h>
+#include <subcmd/help.h>
+
+static int test__load_cmdnames(struct test_suite *test __maybe_unused,
+			       int subtest __maybe_unused)
+{
+	struct cmdnames cmds = {};
+
+	add_cmdname(&cmds, "aaa", 3);
+	add_cmdname(&cmds, "foo", 3);
+	add_cmdname(&cmds, "xyz", 3);
+
+	TEST_ASSERT_VAL("cannot find cmd", is_in_cmdlist(&cmds, "aaa") == 1);
+	TEST_ASSERT_VAL("wrong cmd", is_in_cmdlist(&cmds, "bar") == 0);
+	TEST_ASSERT_VAL("case sensitive", is_in_cmdlist(&cmds, "XYZ") == 0);
+
+	clean_cmdnames(&cmds);
+	return TEST_OK;
+}
+
+static int test__uniq_cmdnames(struct test_suite *test __maybe_unused,
+			       int subtest __maybe_unused)
+{
+	struct cmdnames cmds = {};
+
+	/* uniq() assumes it's sorted */
+	add_cmdname(&cmds, "aaa", 3);
+	add_cmdname(&cmds, "aaa", 3);
+	add_cmdname(&cmds, "bbb", 3);
+
+	TEST_ASSERT_VAL("invalid original size", cmds.cnt == 3);
+	/* uniquify command names (to remove second 'aaa') */
+	uniq(&cmds);
+	TEST_ASSERT_VAL("invalid final size", cmds.cnt == 2);
+
+	TEST_ASSERT_VAL("cannot find cmd", is_in_cmdlist(&cmds, "aaa") == 1);
+	TEST_ASSERT_VAL("cannot find cmd", is_in_cmdlist(&cmds, "bbb") == 1);
+	TEST_ASSERT_VAL("wrong cmd", is_in_cmdlist(&cmds, "ccc") == 0);
+
+	clean_cmdnames(&cmds);
+	return TEST_OK;
+}
+
+static int test__exclude_cmdnames(struct test_suite *test __maybe_unused,
+				  int subtest __maybe_unused)
+{
+	struct cmdnames cmds1 = {};
+	struct cmdnames cmds2 = {};
+
+	add_cmdname(&cmds1, "aaa", 3);
+	add_cmdname(&cmds1, "bbb", 3);
+	add_cmdname(&cmds1, "ccc", 3);
+	add_cmdname(&cmds1, "ddd", 3);
+	add_cmdname(&cmds1, "eee", 3);
+	add_cmdname(&cmds1, "fff", 3);
+	add_cmdname(&cmds1, "ggg", 3);
+	add_cmdname(&cmds1, "hhh", 3);
+	add_cmdname(&cmds1, "iii", 3);
+	add_cmdname(&cmds1, "jjj", 3);
+
+	add_cmdname(&cmds2, "bbb", 3);
+	add_cmdname(&cmds2, "eee", 3);
+	add_cmdname(&cmds2, "jjj", 3);
+
+	TEST_ASSERT_VAL("invalid original size", cmds1.cnt == 10);
+	TEST_ASSERT_VAL("invalid original size", cmds2.cnt == 3);
+
+	/* remove duplicate command names in cmds1 */
+	exclude_cmds(&cmds1, &cmds2);
+
+	TEST_ASSERT_VAL("invalid excluded size", cmds1.cnt == 7);
+	TEST_ASSERT_VAL("invalid excluded size", cmds2.cnt == 3);
+
+	/* excluded commands should not belong to cmds1 */
+	TEST_ASSERT_VAL("cannot find cmd", is_in_cmdlist(&cmds1, "aaa") == 1);
+	TEST_ASSERT_VAL("wrong cmd", is_in_cmdlist(&cmds1, "bbb") == 0);
+	TEST_ASSERT_VAL("cannot find cmd", is_in_cmdlist(&cmds1, "ccc") == 1);
+	TEST_ASSERT_VAL("cannot find cmd", is_in_cmdlist(&cmds1, "ddd") == 1);
+	TEST_ASSERT_VAL("wrong cmd", is_in_cmdlist(&cmds1, "eee") == 0);
+	TEST_ASSERT_VAL("cannot find cmd", is_in_cmdlist(&cmds1, "fff") == 1);
+	TEST_ASSERT_VAL("cannot find cmd", is_in_cmdlist(&cmds1, "ggg") == 1);
+	TEST_ASSERT_VAL("cannot find cmd", is_in_cmdlist(&cmds1, "hhh") == 1);
+	TEST_ASSERT_VAL("cannot find cmd", is_in_cmdlist(&cmds1, "iii") == 1);
+	TEST_ASSERT_VAL("wrong cmd", is_in_cmdlist(&cmds1, "jjj") == 0);
+
+	/* they should be only in cmds2 */
+	TEST_ASSERT_VAL("cannot find cmd", is_in_cmdlist(&cmds2, "bbb") == 1);
+	TEST_ASSERT_VAL("cannot find cmd", is_in_cmdlist(&cmds2, "eee") == 1);
+	TEST_ASSERT_VAL("cannot find cmd", is_in_cmdlist(&cmds2, "jjj") == 1);
+
+	clean_cmdnames(&cmds1);
+	clean_cmdnames(&cmds2);
+	return TEST_OK;
+}
+
+static int test__exclude_cmdnames_no_overlap(struct test_suite *test __maybe_unused,
+					     int subtest __maybe_unused)
+{
+	struct cmdnames cmds1 = {};
+	struct cmdnames cmds2 = {};
+
+	add_cmdname(&cmds1, "read-vdso32", 11);
+	add_cmdname(&cmds2, "archive", 7);
+
+	TEST_ASSERT_VAL("invalid original size", cmds1.cnt == 1);
+	TEST_ASSERT_VAL("invalid original size", cmds2.cnt == 1);
+
+	exclude_cmds(&cmds1, &cmds2);
+
+	TEST_ASSERT_VAL("invalid excluded size", cmds1.cnt == 1);
+	TEST_ASSERT_VAL("invalid excluded size", cmds2.cnt == 1);
+
+	TEST_ASSERT_VAL("cannot find cmd", is_in_cmdlist(&cmds1, "read-vdso32") == 1);
+	TEST_ASSERT_VAL("wrong cmd", is_in_cmdlist(&cmds1, "archive") == 0);
+
+	clean_cmdnames(&cmds1);
+	clean_cmdnames(&cmds2);
+	return TEST_OK;
+}
+
+static struct test_case tests__subcmd_help[] = {
+	TEST_CASE("Load subcmd names", load_cmdnames),
+	TEST_CASE("Uniquify subcmd names", uniq_cmdnames),
+	TEST_CASE("Exclude duplicate subcmd names", exclude_cmdnames),
+	TEST_CASE("Exclude disjoint subcmd names", exclude_cmdnames_no_overlap),
+	{	.name = NULL, }
+};
+
+struct test_suite suite__subcmd_help = {
+	.desc = "libsubcmd help tests",
+	.test_cases = tests__subcmd_help,
+};