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, 76 insertions, 0 deletions

diff --git a/tools/testing/selftests/clock-helpers.h b/tools/testing/selftests/clock-helpers.h
new file mode 100644
index 000000000..01451f538
--- /dev/null
+++ b/tools/testing/selftests/clock-helpers.h
@@ -0,0 +1,76 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef __CLOCK_HELPERS_H
+#define __CLOCK_HELPERS_H
+
+#include <sys/types.h>
+#include <time.h>
+
+#define MSEC_PER_SEC	1000LL
+#define USEC_PER_MSEC	1000LL
+#define NSEC_PER_USEC	1000LL
+#define NSEC_PER_MSEC	1000000LL
+#define USEC_PER_SEC	1000000LL
+#define NSEC_PER_SEC	1000000000LL
+#define PSEC_PER_SEC	1000000000000LL
+#define FSEC_PER_SEC	1000000000000000LL
+
+#ifndef CLOCK_AUX
+#define CLOCK_AUX	16
+#endif
+
+#ifndef MAX_AUX_CLOCKS
+#define MAX_AUX_CLOCKS	8
+#endif
+
+#ifndef CLOCK_AUX_LAST
+#define CLOCK_AUX_LAST	(CLOCK_AUX + MAX_AUX_CLOCKS - 1)
+#endif
+
+__attribute__((unused))
+static inline const char *clock_name(clockid_t clockid)
+{
+	switch (clockid) {
+	case CLOCK_REALTIME:
+		return "CLOCK_REALTIME";
+	case CLOCK_MONOTONIC:
+		return "CLOCK_MONOTONIC";
+	case CLOCK_PROCESS_CPUTIME_ID:
+		return "CLOCK_PROCESS_CPUTIME_ID";
+	case CLOCK_THREAD_CPUTIME_ID:
+		return "CLOCK_THREAD_CPUTIME_ID";
+	case CLOCK_MONOTONIC_RAW:
+		return "CLOCK_MONOTONIC_RAW";
+	case CLOCK_REALTIME_COARSE:
+		return "CLOCK_REALTIME_COARSE";
+	case CLOCK_MONOTONIC_COARSE:
+		return "CLOCK_MONOTONIC_COARSE";
+	case CLOCK_BOOTTIME:
+		return "CLOCK_BOOTTIME";
+	case CLOCK_REALTIME_ALARM:
+		return "CLOCK_REALTIME_ALARM";
+	case CLOCK_BOOTTIME_ALARM:
+		return "CLOCK_BOOTTIME_ALARM";
+	case CLOCK_TAI:
+		return "CLOCK_TAI";
+	case CLOCK_AUX + 0:
+		return "CLOCK_AUX0";
+	case CLOCK_AUX + 1:
+		return "CLOCK_AUX1";
+	case CLOCK_AUX + 2:
+		return "CLOCK_AUX2";
+	case CLOCK_AUX + 3:
+		return "CLOCK_AUX3";
+	case CLOCK_AUX + 4:
+		return "CLOCK_AUX4";
+	case CLOCK_AUX + 5:
+		return "CLOCK_AUX5";
+	case CLOCK_AUX + 6:
+		return "CLOCK_AUX6";
+	case CLOCK_AUX + 7:
+		return "CLOCK_AUX7";
+	};
+	return "UNKNOWN_CLOCKID";
+}
+
+#endif /* __CLOCK_HELPERS_H */