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, 92 insertions, 0 deletions

diff --git a/tools/perf/util/debug.h b/tools/perf/util/debug.h
new file mode 100644
index 000000000..6b737e195
--- /dev/null
+++ b/tools/perf/util/debug.h
@@ -0,0 +1,92 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/* For debugging general purposes */
+#ifndef __PERF_DEBUG_H
+#define __PERF_DEBUG_H
+
+#include <stdarg.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <linux/compiler.h>
+
+extern int verbose;
+extern int debug_kmaps;
+extern int debug_peo_args;
+extern bool quiet, dump_trace;
+extern int debug_ordered_events;
+extern int debug_data_convert;
+extern int debug_type_profile;
+
+#ifndef pr_fmt
+#define pr_fmt(fmt) fmt
+#endif
+
+#define pr_err(fmt, ...) \
+	eprintf(0, verbose, pr_fmt(fmt), ##__VA_ARGS__)
+#define pr_warning(fmt, ...) \
+	eprintf(0, verbose, pr_fmt(fmt), ##__VA_ARGS__)
+#define pr_warning_once(fmt, ...) ({		\
+	static int __warned;			\
+	if (unlikely(!__warned)) {		\
+		pr_warning(fmt, ##__VA_ARGS__); \
+		__warned = 1;			\
+	}					\
+})
+#define pr_info(fmt, ...) \
+	eprintf(0, verbose, pr_fmt(fmt), ##__VA_ARGS__)
+#define pr_debug(fmt, ...) \
+	eprintf(1, verbose, pr_fmt(fmt), ##__VA_ARGS__)
+#define pr_debugN(n, fmt, ...) \
+	eprintf(n, verbose, pr_fmt(fmt), ##__VA_ARGS__)
+#define pr_debug2(fmt, ...) pr_debugN(2, pr_fmt(fmt), ##__VA_ARGS__)
+#define pr_debug3(fmt, ...) pr_debugN(3, pr_fmt(fmt), ##__VA_ARGS__)
+#define pr_debug4(fmt, ...) pr_debugN(4, pr_fmt(fmt), ##__VA_ARGS__)
+
+/* Special macro to print perf_event_open arguments/return value. */
+#define pr_debug2_peo(fmt, ...) {				\
+	if (debug_peo_args)						\
+		pr_debugN(0, pr_fmt(fmt), ##__VA_ARGS__);	\
+	else							\
+		pr_debugN(2, pr_fmt(fmt), ##__VA_ARGS__);	\
+}
+
+#define pr_time_N(n, var, t, fmt, ...) \
+	eprintf_time(n, var, t, fmt, ##__VA_ARGS__)
+
+#define pr_oe_time(t, fmt, ...)  pr_time_N(1, debug_ordered_events, t, pr_fmt(fmt), ##__VA_ARGS__)
+#define pr_oe_time2(t, fmt, ...) pr_time_N(2, debug_ordered_events, t, pr_fmt(fmt), ##__VA_ARGS__)
+
+#define STRERR_BUFSIZE	128	/* For the buffer size of str_error_r */
+
+union perf_event;
+
+int dump_printf(const char *fmt, ...) __printf(1, 2);
+void trace_event(union perf_event *event);
+
+int ui__error(const char *format, ...) __printf(1, 2);
+int ui__warning(const char *format, ...) __printf(1, 2);
+#define ui__warning_once(format, ...) ({		\
+	static int __warned;				\
+	if (unlikely(!__warned)) {			\
+		ui__warning(format, ##__VA_ARGS__);	\
+		__warned = 1;				\
+	}						\
+})
+
+void pr_stat(const char *fmt, ...);
+
+int eprintf(int level, int var, const char *fmt, ...) __printf(3, 4);
+int eprintf_time(int level, int var, u64 t, const char *fmt, ...) __printf(4, 5);
+int veprintf(int level, int var, const char *fmt, va_list args);
+
+int perf_debug_option(const char *str);
+FILE *debug_file(void);
+void debug_set_file(FILE *file);
+void debug_set_display_time(bool set);
+void perf_debug_setup(void);
+int perf_quiet_option(void);
+
+void __dump_stack(FILE *file, void **stackdump, size_t stackdump_size);
+void dump_stack(void);
+void sighandler_dump_stack(int sig);
+
+#endif	/* __PERF_DEBUG_H */