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/lib/perf/threadmap.c | 118 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 118 insertions(+) create mode 100644 tools/lib/perf/threadmap.c (limited to 'tools/lib/perf/threadmap.c') diff --git a/tools/lib/perf/threadmap.c b/tools/lib/perf/threadmap.c new file mode 100644 index 000000000..db431b036 --- /dev/null +++ b/tools/lib/perf/threadmap.c @@ -0,0 +1,118 @@ +// SPDX-License-Identifier: GPL-2.0 +#include +#include +#include +#include +#include +#include +#include + +static void perf_thread_map__reset(struct perf_thread_map *map, int start, int nr) +{ + size_t size = (nr - start) * sizeof(map->map[0]); + + memset(&map->map[start], 0, size); + map->err_thread = -1; +} + +struct perf_thread_map *perf_thread_map__realloc(struct perf_thread_map *map, int nr) +{ + size_t size = sizeof(*map) + sizeof(map->map[0]) * nr; + int start = map ? map->nr : 0; + + map = realloc(map, size); + /* + * We only realloc to add more items, let's reset new items. + */ + if (map) + perf_thread_map__reset(map, start, nr); + + return map; +} + +#define thread_map__alloc(__nr) perf_thread_map__realloc(NULL, __nr) + +void perf_thread_map__set_pid(struct perf_thread_map *map, int idx, pid_t pid) +{ + map->map[idx].pid = pid; +} + +char *perf_thread_map__comm(struct perf_thread_map *map, int idx) +{ + return map->map[idx].comm; +} + +struct perf_thread_map *perf_thread_map__new_array(int nr_threads, pid_t *array) +{ + struct perf_thread_map *threads = thread_map__alloc(nr_threads); + int i; + + if (!threads) + return NULL; + + for (i = 0; i < nr_threads; i++) + perf_thread_map__set_pid(threads, i, array ? array[i] : -1); + + threads->nr = nr_threads; + refcount_set(&threads->refcnt, 1); + + return threads; +} + +struct perf_thread_map *perf_thread_map__new_dummy(void) +{ + return perf_thread_map__new_array(1, NULL); +} + +static void perf_thread_map__delete(struct perf_thread_map *threads) +{ + if (threads) { + int i; + + WARN_ONCE(refcount_read(&threads->refcnt) != 0, + "thread map refcnt unbalanced\n"); + for (i = 0; i < threads->nr; i++) + free(perf_thread_map__comm(threads, i)); + free(threads); + } +} + +struct perf_thread_map *perf_thread_map__get(struct perf_thread_map *map) +{ + if (map) + refcount_inc(&map->refcnt); + return map; +} + +void perf_thread_map__put(struct perf_thread_map *map) +{ + if (map && refcount_dec_and_test(&map->refcnt)) + perf_thread_map__delete(map); +} + +int perf_thread_map__nr(struct perf_thread_map *threads) +{ + return threads ? threads->nr : 1; +} + +pid_t perf_thread_map__pid(struct perf_thread_map *map, int idx) +{ + if (!map) { + assert(idx == 0); + return -1; + } + + return map->map[idx].pid; +} + +int perf_thread_map__idx(struct perf_thread_map *threads, pid_t pid) +{ + if (!threads) + return pid == -1 ? 0 : -1; + + for (int i = 0; i < threads->nr; ++i) { + if (threads->map[i].pid == pid) + return i; + } + return -1; +} -- cgit v1.3.1