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/tests/sw-clock.c | 152 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 152 insertions(+) create mode 100644 tools/perf/tests/sw-clock.c (limited to 'tools/perf/tests/sw-clock.c') diff --git a/tools/perf/tests/sw-clock.c b/tools/perf/tests/sw-clock.c new file mode 100644 index 000000000..d18185881 --- /dev/null +++ b/tools/perf/tests/sw-clock.c @@ -0,0 +1,152 @@ +// SPDX-License-Identifier: GPL-2.0 +#include +#include +#include +#include +#include +#include +#include +#include + +#include "tests.h" +#include "util/debug.h" +#include "util/evsel.h" +#include "util/evlist.h" +#include "util/cpumap.h" +#include "util/mmap.h" +#include "util/sample.h" +#include "util/thread_map.h" +#include +#include + +#define NR_LOOPS 10000000 + +/* + * This test will open software clock events (cpu-clock, task-clock) + * then check their frequency -> period conversion has no artifact of + * setting period to 1 forcefully. + */ +static int __test__sw_clock_freq(enum perf_sw_ids clock_id) +{ + int i, err = -1; + volatile int tmp __maybe_unused = 0; + u64 total_periods = 0; + int nr_samples = 0; + char sbuf[STRERR_BUFSIZE]; + union perf_event *event; + struct evsel *evsel; + struct evlist *evlist; + struct perf_event_attr attr = { + .type = PERF_TYPE_SOFTWARE, + .config = clock_id, + .sample_type = PERF_SAMPLE_PERIOD, + .exclude_kernel = 1, + .disabled = 1, + .freq = 1, + }; + struct perf_cpu_map *cpus = NULL; + struct perf_thread_map *threads = NULL; + struct mmap *md; + + attr.sample_freq = 500; + + evlist = evlist__new(); + if (evlist == NULL) { + pr_debug("evlist__new\n"); + return -1; + } + + evsel = evsel__new(&attr); + if (evsel == NULL) { + pr_debug("evsel__new\n"); + goto out_put_evlist; + } + evlist__add(evlist, evsel); + + cpus = perf_cpu_map__new_any_cpu(); + threads = thread_map__new_by_tid(getpid()); + if (!cpus || !threads) { + err = -ENOMEM; + pr_debug("Not enough memory to create thread/cpu maps\n"); + goto out_put_evlist; + } + + perf_evlist__set_maps(evlist__core(evlist), cpus, threads); + + if (evlist__open(evlist)) { + const char *knob = "/proc/sys/kernel/perf_event_max_sample_rate"; + + err = -errno; + pr_debug("Couldn't open evlist: %s\nHint: check %s, using %" PRIu64 " in this test.\n", + str_error_r(errno, sbuf, sizeof(sbuf)), + knob, (u64)attr.sample_freq); + goto out_put_evlist; + } + + err = evlist__do_mmap(evlist, 128); + if (err < 0) { + pr_debug("failed to mmap event: %d (%s)\n", errno, + str_error_r(errno, sbuf, sizeof(sbuf))); + goto out_put_evlist; + } + + evlist__enable(evlist); + + /* collect samples */ + for (i = 0; i < NR_LOOPS; i++) + tmp++; + + evlist__disable(evlist); + + md = &evlist__mmap(evlist)[0]; + if (perf_mmap__read_init(&md->core) < 0) + goto out_init; + + while ((event = perf_mmap__read_event(&md->core)) != NULL) { + struct perf_sample sample; + + perf_sample__init(&sample, /*all=*/false); + if (event->header.type != PERF_RECORD_SAMPLE) + goto next_event; + + err = evlist__parse_sample(evlist, event, &sample); + if (err < 0) { + pr_debug("Error during parse sample\n"); + perf_sample__exit(&sample); + goto out_put_evlist; + } + + total_periods += sample.period; + nr_samples++; +next_event: + perf_mmap__consume(&md->core); + perf_sample__exit(&sample); + } + perf_mmap__read_done(&md->core); + +out_init: + if ((u64) nr_samples == total_periods) { + pr_debug("All (%d) samples have period value of 1!\n", + nr_samples); + err = -1; + } + +out_put_evlist: + perf_cpu_map__put(cpus); + perf_thread_map__put(threads); + evlist__put(evlist); + return err; +} + +static int test__sw_clock_freq(struct test_suite *test __maybe_unused, int subtest __maybe_unused) +{ + int ret; + + ret = __test__sw_clock_freq(PERF_COUNT_SW_CPU_CLOCK); + if (!ret) + ret = __test__sw_clock_freq(PERF_COUNT_SW_TASK_CLOCK); + + return ret; +} + +DEFINE_SUITE("Software clock events period values", sw_clock_freq); -- cgit v1.3.1