[PATCH v12 16/20] perf intel-tpebs: Use DEFINE_MUTEX for tpebs_mtx

[Ian Rogers <irogers@google.com>]

Replace tpebs_mtx_get() and its pthread_once() initialization helper
tpebs_init() with DEFINE_MUTEX(tpebs_mtx) and static initializers for
control_fd and ack_fd.

Signed-off-by: Ian Rogers <irogers@google.com>
---
 tools/perf/util/intel-tpebs.c | 91 +++++++++++++++--------------------
 1 file changed, 38 insertions(+), 53 deletions(-)

diff --git a/tools/perf/util/intel-tpebs.c b/tools/perf/util/intel-tpebs.c
index 5cb090b27fbd..2edd8297fa1b 100644
--- a/tools/perf/util/intel-tpebs.c
+++ b/tools/perf/util/intel-tpebs.c
@@ -38,12 +38,12 @@
 
 bool tpebs_recording;
 enum tpebs_mode tpebs_mode;
+static DEFINE_MUTEX(tpebs_mtx);
 static LIST_HEAD(tpebs_results);
 static pthread_t tpebs_reader_thread;
 static struct child_process tpebs_cmd;
-static int control_fd[2], ack_fd[2];
-static struct mutex tpebs_mtx;
 static struct cond tpebs_cmd_cond = { .cond = PTHREAD_COND_INITIALIZER };
+static int control_fd[2] = { -1, -1 }, ack_fd[2] = { -1, -1 };
 static bool tpebs_stopping;
 static bool tpebs_enabled;
 static bool tpebs_cmd_in_flight;
@@ -63,23 +63,8 @@ struct tpebs_retire_lat {
 	bool started;
 };
 
-static void tpebs_init(void)
-{
-	mutex_init(&tpebs_mtx);
-	control_fd[0] = control_fd[1] = -1;
-	ack_fd[0] = ack_fd[1] = -1;
-}
-
-static struct mutex *tpebs_mtx_get(void)
-{
-	static pthread_once_t tpebs_once = PTHREAD_ONCE_INIT;
-
-	pthread_once(&tpebs_once, tpebs_init);
-	return &tpebs_mtx;
-}
-
 static struct tpebs_retire_lat *tpebs_retire_lat__find(struct evsel *evsel)
-	__must_hold(tpebs_mtx_get());
+	__must_hold(&tpebs_mtx);
 
 static int evsel__tpebs_start_perf_record(struct evsel *evsel)
 {
@@ -209,19 +194,19 @@ static int process_sample_event(const struct perf_tool *tool __maybe_unused,
 {
 	struct tpebs_retire_lat *t;
 
-	mutex_lock(tpebs_mtx_get());
+	mutex_lock(&tpebs_mtx);
 	if (tpebs_stopping || tpebs_cmd.pid == 0) {
 		/* Record is stopping or has terminated. */
-		mutex_unlock(tpebs_mtx_get());
+		mutex_unlock(&tpebs_mtx);
 		return 0;
 	}
 	t = tpebs_retire_lat__find(sample->evsel);
 	if (!t) {
-		mutex_unlock(tpebs_mtx_get());
+		mutex_unlock(&tpebs_mtx);
 		return -EINVAL;
 	}
 	if (should_ignore_sample(sample, t)) {
-		mutex_unlock(tpebs_mtx_get());
+		mutex_unlock(&tpebs_mtx);
 		return 0;
 	}
 	/*
@@ -231,7 +216,7 @@ static int process_sample_event(const struct perf_tool *tool __maybe_unused,
 	 */
 	t->last = sample->weight3;
 	update_stats(&t->stats, sample->weight3);
-	mutex_unlock(tpebs_mtx_get());
+	mutex_unlock(&tpebs_mtx);
 	return 0;
 }
 
@@ -261,7 +246,7 @@ static void *__sample_reader(void *arg)
 	return NULL;
 }
 
-static int tpebs_send_record_cmd(const char *msg) __must_hold(tpebs_mtx_get())
+static int tpebs_send_record_cmd(const char *msg) __must_hold(&tpebs_mtx)
 {
 	struct pollfd pollfd = { .events = POLLIN, };
 	bool is_stop = !strcmp(msg, EVLIST_CTL_CMD_STOP_TAG);
@@ -272,7 +257,7 @@ static int tpebs_send_record_cmd(const char *msg) __must_hold(tpebs_mtx_get())
 	while (tpebs_cmd_in_flight) {
 		if (!is_stop && tpebs_stopping)
 			return -EBUSY;
-		cond_wait(&tpebs_cmd_cond, tpebs_mtx_get());
+		cond_wait(&tpebs_cmd_cond, &tpebs_mtx);
 	}
 	if (!is_stop && tpebs_stopping)
 		return -EBUSY;
@@ -289,7 +274,7 @@ static int tpebs_send_record_cmd(const char *msg) __must_hold(tpebs_mtx_get())
 	 * Let go of the lock while sending/receiving as blocking can starve the
 	 * sample reading thread.
 	 */
-	mutex_unlock(tpebs_mtx_get());
+	mutex_unlock(&tpebs_mtx);
 
 	/* Send perf record command. */
 	len = scnprintf(cmd_buf, sizeof(cmd_buf), "%s\n", msg);
@@ -317,10 +302,10 @@ static int tpebs_send_record_cmd(const char *msg) __must_hold(tpebs_mtx_get())
 	if (!poll(&pollfd, 1, 500)) {
 		bool stopping, finished;
 
-		mutex_lock(tpebs_mtx_get());
+		mutex_lock(&tpebs_mtx);
 		stopping = tpebs_stopping;
 		finished = !stopping && check_if_command_finished(&tpebs_cmd);
-		mutex_unlock(tpebs_mtx_get());
+		mutex_unlock(&tpebs_mtx);
 		if (stopping) {
 			ret = -EBUSY;
 			goto out;
@@ -340,10 +325,10 @@ static int tpebs_send_record_cmd(const char *msg) __must_hold(tpebs_mtx_get())
 	if (!(pollfd.revents & POLLIN)) {
 		bool stopping, finished;
 
-		mutex_lock(tpebs_mtx_get());
+		mutex_lock(&tpebs_mtx);
 		stopping = tpebs_stopping;
 		finished = !stopping && check_if_command_finished(&tpebs_cmd);
-		mutex_unlock(tpebs_mtx_get());
+		mutex_unlock(&tpebs_mtx);
 		if (stopping) {
 			ret = -EBUSY;
 			goto out;
@@ -365,7 +350,7 @@ static int tpebs_send_record_cmd(const char *msg) __must_hold(tpebs_mtx_get())
 		pr_err("tpebs: perf record control ack failed\n");
 out:
 	/* Re-take lock as expected by caller. */
-	mutex_lock(tpebs_mtx_get());
+	mutex_lock(&tpebs_mtx);
 	tpebs_cmd_in_flight = false;
 	cond_broadcast(&tpebs_cmd_cond);
 	return ret;
@@ -374,7 +359,7 @@ static int tpebs_send_record_cmd(const char *msg) __must_hold(tpebs_mtx_get())
 /*
  * tpebs_stop - stop the sample data read thread and the perf record process.
  */
-static int tpebs_stop(void) __must_hold(tpebs_mtx_get())
+static int tpebs_stop(void) __must_hold(&tpebs_mtx)
 {
 	int ret = 0;
 
@@ -399,9 +384,9 @@ static int tpebs_stop(void) __must_hold(tpebs_mtx_get())
 		 */
 		tpebs_cmd.pid = 0;
 		reader_thread = tpebs_reader_thread;
-		mutex_unlock(tpebs_mtx_get());
+		mutex_unlock(&tpebs_mtx);
 		pthread_join(reader_thread, NULL);
-		mutex_lock(tpebs_mtx_get());
+		mutex_lock(&tpebs_mtx);
 		if (control_fd[0] >= 0) {
 			close(control_fd[0]);
 			control_fd[0] = -1;
@@ -537,20 +522,20 @@ static int evsel__tpebs_prepare(struct evsel *evsel)
 	struct evsel *pos;
 	struct tpebs_retire_lat *tpebs_event;
 
-	mutex_lock(tpebs_mtx_get());
+	mutex_lock(&tpebs_mtx);
 	tpebs_event = tpebs_retire_lat__find(evsel);
 	if (tpebs_event) {
 		/* evsel, or an identically named one, was already prepared. */
-		mutex_unlock(tpebs_mtx_get());
+		mutex_unlock(&tpebs_mtx);
 		return 0;
 	}
 	tpebs_event = tpebs_retire_lat__new(evsel);
 	if (!tpebs_event) {
-		mutex_unlock(tpebs_mtx_get());
+		mutex_unlock(&tpebs_mtx);
 		return -ENOMEM;
 	}
 	list_add_tail(&tpebs_event->nd, &tpebs_results);
-	mutex_unlock(tpebs_mtx_get());
+	mutex_unlock(&tpebs_mtx);
 
 	/*
 	 * Eagerly prepare all other evsels on the list to try to ensure that by
@@ -586,9 +571,9 @@ int evsel__tpebs_open(struct evsel *evsel)
 	if (!tpebs_recording)
 		return 0;
 
-	mutex_lock(tpebs_mtx_get());
+	mutex_lock(&tpebs_mtx);
 	if (tpebs_stopping) {
-		mutex_unlock(tpebs_mtx_get());
+		mutex_unlock(&tpebs_mtx);
 		return -EBUSY;
 	}
 	/* Only start the events once. */
@@ -598,17 +583,17 @@ int evsel__tpebs_open(struct evsel *evsel)
 
 		t = tpebs_retire_lat__find(evsel);
 		valid = t && t->started;
-		mutex_unlock(tpebs_mtx_get());
+		mutex_unlock(&tpebs_mtx);
 		/* May fail as the event wasn't started. */
 		return valid ? 0 : -EBUSY;
 	}
-	mutex_unlock(tpebs_mtx_get());
+	mutex_unlock(&tpebs_mtx);
 
 	ret = evsel__tpebs_prepare(evsel);
 	if (ret)
 		return ret;
 
-	mutex_lock(tpebs_mtx_get());
+	mutex_lock(&tpebs_mtx);
 	if (tpebs_stopping || tpebs_cmd.pid != 0) {
 		ret = -EBUSY;
 		goto out;
@@ -671,14 +656,14 @@ int evsel__tpebs_open(struct evsel *evsel)
 			if (actual_pid > 0) {
 				kill(actual_pid, SIGTERM);
 				while (tpebs_cmd_in_flight)
-					cond_wait(&tpebs_cmd_cond, tpebs_mtx_get());
+					cond_wait(&tpebs_cmd_cond, &tpebs_mtx);
 				tpebs_cmd.pid = 0;
 				if (started_thread) {
 					pthread_t reader_thread = tpebs_reader_thread;
 
-					mutex_unlock(tpebs_mtx_get());
+					mutex_unlock(&tpebs_mtx);
 					pthread_join(reader_thread, NULL);
-					mutex_lock(tpebs_mtx_get());
+					mutex_lock(&tpebs_mtx);
 				}
 			}
 			if (tpebs_cmd.out >= 0) {
@@ -709,7 +694,7 @@ int evsel__tpebs_open(struct evsel *evsel)
 			tpebs_stopping = false;
 		}
 	}
-	mutex_unlock(tpebs_mtx_get());
+	mutex_unlock(&tpebs_mtx);
 	return ret;
 }
 
@@ -729,7 +714,7 @@ int evsel__tpebs_read(struct evsel *evsel, int cpu_map_idx, int thread)
 
 	count = perf_counts(evsel->counts, cpu_map_idx, thread);
 
-	mutex_lock(tpebs_mtx_get());
+	mutex_lock(&tpebs_mtx);
 	t = tpebs_retire_lat__find(evsel);
 	/*
 	 * If reading the first tpebs result, send a ping to the record
@@ -738,10 +723,10 @@ int evsel__tpebs_read(struct evsel *evsel, int cpu_map_idx, int thread)
 	 */
 	if (t && &t->nd == tpebs_results.next) {
 		ret = tpebs_send_record_cmd(EVLIST_CTL_CMD_PING_TAG);
-		mutex_unlock(tpebs_mtx_get());
+		mutex_unlock(&tpebs_mtx);
 		if (ret)
 			return ret;
-		mutex_lock(tpebs_mtx_get());
+		mutex_lock(&tpebs_mtx);
 	}
 	if (t == NULL || t->stats.n == 0) {
 		/* No sample data, use default. */
@@ -780,7 +765,7 @@ int evsel__tpebs_read(struct evsel *evsel, int cpu_map_idx, int thread)
 			break;
 		}
 	}
-	mutex_unlock(tpebs_mtx_get());
+	mutex_unlock(&tpebs_mtx);
 
 	if (old_count) {
 		count->val = old_count->val + val;
@@ -805,7 +790,7 @@ void evsel__tpebs_close(struct evsel *evsel)
 {
 	struct tpebs_retire_lat *t;
 
-	mutex_lock(tpebs_mtx_get());
+	mutex_lock(&tpebs_mtx);
 	t = tpebs_retire_lat__find(evsel);
 	if (t) {
 		list_del_init(&t->nd);
@@ -814,5 +799,5 @@ void evsel__tpebs_close(struct evsel *evsel)
 		if (list_empty(&tpebs_results))
 			tpebs_stop();
 	}
-	mutex_unlock(tpebs_mtx_get());
+	mutex_unlock(&tpebs_mtx);
 }
-- 
2.56.0.542.g3ef89b7020-goog