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/trace-event.c | 127 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 127 insertions(+) create mode 100644 tools/perf/util/trace-event.c (limited to 'tools/perf/util/trace-event.c') diff --git a/tools/perf/util/trace-event.c b/tools/perf/util/trace-event.c new file mode 100644 index 000000000..000c1e1d6 --- /dev/null +++ b/tools/perf/util/trace-event.c @@ -0,0 +1,127 @@ +// SPDX-License-Identifier: GPL-2.0 +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include "trace-event.h" +#include "machine.h" + +/* + * global trace_event object used by trace_event__tp_format + * + * TODO There's no cleanup call for this. Add some sort of + * __exit function support and call trace_event__cleanup + * there. + */ +static struct trace_event tevent; +static bool tevent_initialized; + +int trace_event__init(struct trace_event *t) +{ + struct tep_handle *pevent; + + trace_event__cleanup(t); + + pevent = tep_alloc(); + + if (pevent) { + t->plugin_list = tep_load_plugins(pevent); + t->pevent = pevent; + } + + return pevent ? 0 : -1; +} + +static int trace_event__init2(void) +{ + int be = tep_is_bigendian(); + struct tep_handle *pevent; + + if (trace_event__init(&tevent)) + return -1; + + pevent = tevent.pevent; + tep_set_flag(pevent, TEP_NSEC_OUTPUT); + tep_set_file_bigendian(pevent, be); + tep_set_local_bigendian(pevent, be); + tevent_initialized = true; + return 0; +} + +int trace_event__register_resolver(struct machine *machine, + tep_func_resolver_t *func) +{ + if (!tevent_initialized && trace_event__init2()) + return -1; + + return tep_set_function_resolver(tevent.pevent, func, machine); +} + +void trace_event__cleanup(struct trace_event *t) +{ + if (!t->pevent) + return; + + tep_unload_plugins(t->plugin_list, t->pevent); + tep_free(t->pevent); + t->pevent = NULL; + t->plugin_list = NULL; +} + +/* + * Returns pointer with encoded error via interface. + */ +static struct tep_event* +tp_format(const char *sys, const char *name) +{ + char *tp_dir = get_events_file(sys); + struct tep_handle *pevent = tevent.pevent; + struct tep_event *event = NULL; + char path[PATH_MAX]; + size_t size; + char *data; + int err; + + if (!tp_dir) + return ERR_PTR(-errno); + + scnprintf(path, PATH_MAX, "%s/%s/format", tp_dir, name); + put_events_file(tp_dir); + + err = filename__read_str(path, &data, &size); + if (err) + return ERR_PTR(err); + + tep_parse_format(pevent, &event, data, size, sys); + + free(data); + return event; +} + +/* + * Returns pointer with encoded error via interface. + */ +struct tep_event* +trace_event__tp_format(const char *sys, const char *name) +{ + if (!tevent_initialized && trace_event__init2()) + return ERR_PTR(-ENOMEM); + + return tp_format(sys, name); +} + +struct tep_event *trace_event__tp_format_id(int id) +{ + if (!tevent_initialized && trace_event__init2()) + return ERR_PTR(-ENOMEM); + + return tep_find_event(tevent.pevent, id); +} -- cgit v1.3.1