perf bench synthesize: Avoid use of global perf_env

The benchmark doesn't use a data file and so the header perf_env isn't
used. Stack allocate a host perf_env for use to avoid the use of the
global perf_env.

Signed-off-by: Ian Rogers <irogers@google.com>
Link: https://lore.kernel.org/r/20250724163302.596743-16-irogers@google.com
Signed-off-by: Namhyung Kim <namhyung@kernel.org>

Author: captain5050

tools/perf/bench/synthesize.c

@@ -114,12 +114,16 @@ static int run_single_threaded(void)
 		.pid = "self",
 	};
 	struct perf_thread_map *threads;
+	struct perf_env host_env;
 	int err;
 
 	perf_set_singlethreaded();
-	session = perf_session__new(NULL, NULL);
+	perf_env__init(&host_env);
+	session = __perf_session__new(/*data=*/NULL, /*tool=*/NULL,
+				      /*trace_event_repipe=*/false, &host_env);
 	if (IS_ERR(session)) {
 		pr_err("Session creation failed.\n");
+		perf_env__exit(&host_env);
 		return PTR_ERR(session);
 	}
 	threads = thread_map__new_by_pid(getpid());
@@ -144,6 +148,7 @@ static int run_single_threaded(void)
 		perf_thread_map__put(threads);
 
 	perf_session__delete(session);
+	perf_env__exit(&host_env);
 	return err;
 }
 
@@ -154,17 +159,21 @@ static int do_run_multi_threaded(struct target *target,
 	u64 runtime_us;
 	unsigned int i;
 	double time_average, time_stddev, event_average, event_stddev;
-	int err;
+	int err = 0;
 	struct stats time_stats, event_stats;
 	struct perf_session *session;
+	struct perf_env host_env;
 
+	perf_env__init(&host_env);
 	init_stats(&time_stats);
 	init_stats(&event_stats);
 	for (i = 0; i < multi_iterations; i++) {
-		session = perf_session__new(NULL, NULL);
-		if (IS_ERR(session))
-			return PTR_ERR(session);
-
+		session = __perf_session__new(/*data=*/NULL, /*tool=*/NULL,
+					      /*trace_event_repipe=*/false, &host_env);
+		if (IS_ERR(session)) {
+			err = PTR_ERR(session);
+			goto err_out;
+		}
 		atomic_set(&event_count, 0);
 		gettimeofday(&start, NULL);
 		err = __machine__synthesize_threads(&session->machines.host,
@@ -175,7 +184,7 @@ static int do_run_multi_threaded(struct target *target,
 						nr_threads_synthesize);
 		if (err) {
 			perf_session__delete(session);
-			return err;
+			goto err_out;
 		}
 
 		gettimeofday(&end, NULL);
@@ -198,7 +207,9 @@ static int do_run_multi_threaded(struct target *target,
 
 	printf("    Average time per event %.3f usec\n",
 		time_average / event_average);
-	return 0;
+err_out:
+	perf_env__exit(&host_env);
+	return err;
 }
 
 static int run_multi_threaded(void)