From 4617721c502b2ddaa4e324e86da4997edf738fa5 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Wed, 2 Sep 2026 09:55:01 -0400 Subject: ftrace: Synchronize the initialization of ftrace_ops 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 --- tools/perf/util/trigger.h | 95 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 95 insertions(+) create mode 100644 tools/perf/util/trigger.h (limited to 'tools/perf/util/trigger.h') diff --git a/tools/perf/util/trigger.h b/tools/perf/util/trigger.h new file mode 100644 index 000000000..33e997f9c --- /dev/null +++ b/tools/perf/util/trigger.h @@ -0,0 +1,95 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef __TRIGGER_H_ +#define __TRIGGER_H_ 1 + +#include "asm/bug.h" + +/* + * Use trigger to model operations which need to be executed when + * an event (a signal, for example) is observed. + * + * States and transits: + * + * + * OFF--> ON --> READY --(hit)--> HIT + * ^ | + * | (ready) + * | | + * \_____________/ + * + * is_hit and is_ready are two key functions to query the state of + * a trigger. is_hit means the event already happen; is_ready means the + * trigger is waiting for the event. + */ + +struct trigger { + volatile enum { + TRIGGER_ERROR = -2, + TRIGGER_OFF = -1, + TRIGGER_ON = 0, + TRIGGER_READY = 1, + TRIGGER_HIT = 2, + } state; + const char *name; +}; + +#define TRIGGER_WARN_ONCE(t, exp) \ + WARN_ONCE(t->state != exp, "trigger '%s' state transist error: %d in %s()\n", \ + t->name, t->state, __func__) + +static inline bool trigger_is_available(struct trigger *t) +{ + return t->state >= 0; +} + +static inline bool trigger_is_error(struct trigger *t) +{ + return t->state <= TRIGGER_ERROR; +} + +static inline void trigger_on(struct trigger *t) +{ + TRIGGER_WARN_ONCE(t, TRIGGER_OFF); + t->state = TRIGGER_ON; +} + +static inline void trigger_ready(struct trigger *t) +{ + if (!trigger_is_available(t)) + return; + t->state = TRIGGER_READY; +} + +static inline void trigger_hit(struct trigger *t) +{ + if (!trigger_is_available(t)) + return; + TRIGGER_WARN_ONCE(t, TRIGGER_READY); + t->state = TRIGGER_HIT; +} + +static inline void trigger_off(struct trigger *t) +{ + if (!trigger_is_available(t)) + return; + t->state = TRIGGER_OFF; +} + +static inline void trigger_error(struct trigger *t) +{ + t->state = TRIGGER_ERROR; +} + +static inline bool trigger_is_ready(struct trigger *t) +{ + return t->state == TRIGGER_READY; +} + +static inline bool trigger_is_hit(struct trigger *t) +{ + return t->state == TRIGGER_HIT; +} + +#define DEFINE_TRIGGER(n) \ +struct trigger n = {.state = TRIGGER_OFF, .name = #n} +#endif -- cgit v1.3.1