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/threads.h | 35 +++++++++++++++++++++++++++++++++++ 1 file changed, 35 insertions(+) create mode 100644 tools/perf/util/threads.h (limited to 'tools/perf/util/threads.h') diff --git a/tools/perf/util/threads.h b/tools/perf/util/threads.h new file mode 100644 index 000000000..da68d2223 --- /dev/null +++ b/tools/perf/util/threads.h @@ -0,0 +1,35 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef __PERF_THREADS_H +#define __PERF_THREADS_H + +#include "hashmap.h" +#include "rwsem.h" + +struct thread; + +#define THREADS__TABLE_BITS 3 +#define THREADS__TABLE_SIZE (1 << THREADS__TABLE_BITS) + +struct threads_table_entry { + /* Key is tid, value is struct thread. */ + struct hashmap shard; + struct rw_semaphore lock; + struct thread *last_match; +}; + +struct threads { + struct threads_table_entry table[THREADS__TABLE_SIZE]; +}; + +void threads__init(struct threads *threads); +void threads__exit(struct threads *threads); +size_t threads__nr(struct threads *threads); +struct thread *threads__find(struct threads *threads, pid_t tid); +struct thread *threads__findnew(struct threads *threads, pid_t pid, pid_t tid, bool *created); +void threads__remove_all_threads(struct threads *threads); +void threads__remove(struct threads *threads, struct thread *thread); +int threads__for_each_thread(struct threads *threads, + int (*fn)(struct thread *thread, void *data), + void *data); + +#endif /* __PERF_THREADS_H */ -- cgit v1.3.1