linux-kernel - [PATCH v1 06/14] perf intel-tpebs: Inline get_perf_record

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Message-ID: <20250324223452.208081-7-irogers@google.com>
Date: Mon, 24 Mar 2025 15:34:44 -0700
From: Ian Rogers <irogers@...gle.com>
To: Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>, 
	Arnaldo Carvalho de Melo <acme@...nel.org>, Namhyung Kim <namhyung@...nel.org>, 
	Mark Rutland <mark.rutland@....com>, 
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>, Jiri Olsa <jolsa@...nel.org>, 
	Ian Rogers <irogers@...gle.com>, Adrian Hunter <adrian.hunter@...el.com>, 
	Kan Liang <kan.liang@...ux.intel.com>, Weilin Wang <weilin.wang@...el.com>, 
	James Clark <james.clark@...aro.org>, Xu Yang <xu.yang_2@....com>, 
	John Garry <john.g.garry@...cle.com>, Howard Chu <howardchu95@...il.com>, 
	Levi Yun <yeoreum.yun@....com>, Dominique Martinet <asmadeus@...ewreck.org>, 
	linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH v1 06/14] perf intel-tpebs: Inline get_perf_record_args

Code is short enough to be inlined and there are no error cases when
made inline. Make the implicit NULL pointer at the end of the argv
explicit. Move the fixed number of arguments before the variable
number of arguments. Correctly size the argv allocation and zero when
feeing to avoid a dangling pointer.

Signed-off-by: Ian Rogers <irogers@...gle.com>
---
 tools/perf/util/intel-tpebs.c | 75 +++++++++++++----------------------
 1 file changed, 28 insertions(+), 47 deletions(-)

diff --git a/tools/perf/util/intel-tpebs.c b/tools/perf/util/intel-tpebs.c
index e5ca58599b5f..3141b7d2e94f 100644
--- a/tools/perf/util/intel-tpebs.c
+++ b/tools/perf/util/intel-tpebs.c
@@ -46,72 +46,53 @@ struct tpebs_retire_lat {
 	double val;
 };
 
-static int get_perf_record_args(const char **record_argv, char buf[],
-				const char *cpumap_buf)
+static int evsel__tpebs_start_perf_record(struct evsel *evsel, int control_fd[], int ack_fd[])
 {
-	struct tpebs_retire_lat *e;
-	int i = 0;
+	const char **record_argv;
+	int tpebs_event_size = 0, i = 0, ret;
+	char control_fd_buf[32];
+	char cpumap_buf[50];
+	struct tpebs_retire_lat *t;
+
+	list_for_each_entry(t, &tpebs_results, nd)
+		tpebs_event_size++;
 
-	pr_debug("tpebs: Prepare perf record for retire_latency\n");
+	record_argv = malloc((10 + 2 * tpebs_event_size) * sizeof(*record_argv));
+	if (!record_argv)
+		return -ENOMEM;
 
 	record_argv[i++] = "perf";
 	record_argv[i++] = "record";
 	record_argv[i++] = "-W";
 	record_argv[i++] = "--synth=no";
-	record_argv[i++] = buf;
 
-	if (!cpumap_buf) {
-		pr_err("tpebs: Require cpumap list to run sampling\n");
-		return -ECANCELED;
-	}
-	/* Use -C when cpumap_buf is not "-1" */
-	if (strcmp(cpumap_buf, "-1")) {
+	scnprintf(control_fd_buf, sizeof(control_fd_buf), "--control=fd:%d,%d",
+		  control_fd[0], ack_fd[1]);
+	record_argv[i++] = control_fd_buf;
+
+	record_argv[i++] = "-o";
+	record_argv[i++] = PERF_DATA;
+
+	if (!perf_cpu_map__is_any_cpu_or_is_empty(evsel->evlist->core.user_requested_cpus)) {
+		cpu_map__snprint(evsel->evlist->core.user_requested_cpus, cpumap_buf,
+				 sizeof(cpumap_buf));
 		record_argv[i++] = "-C";
 		record_argv[i++] = cpumap_buf;
 	}
 
-	list_for_each_entry(e, &tpebs_results, nd) {
+	list_for_each_entry(t, &tpebs_results, nd) {
 		record_argv[i++] = "-e";
-		record_argv[i++] = e->name;
+		record_argv[i++] = t->name;
 	}
-
-	record_argv[i++] = "-o";
-	record_argv[i++] = PERF_DATA;
-
-	return 0;
-}
-
-static int evsel__tpebs_start_perf_record(struct evsel *evsel, int control_fd[], int ack_fd[])
-{
-	const char **record_argv;
-	size_t tpebs_event_size = 0;
-	int ret;
-	char buf[32];
-	char cpumap_buf[50];
-	struct tpebs_retire_lat *t;
-
-	cpu_map__snprint(evsel->evlist->core.user_requested_cpus, cpumap_buf,
-			 sizeof(cpumap_buf));
-
-	scnprintf(buf, sizeof(buf), "--control=fd:%d,%d", control_fd[0], ack_fd[1]);
-
-	list_for_each_entry(t, &tpebs_results, nd)
-		tpebs_event_size++;
-
-	record_argv = calloc(12 + 2 * tpebs_event_size, sizeof(char *));
-	if (!record_argv)
-		return -ENOMEM;
-
-	ret = get_perf_record_args(record_argv, buf, cpumap_buf);
-	if (ret)
-		goto out;
+	record_argv[i++] = NULL;
+	assert(i == 10 + 2 * tpebs_event_size || i == 8 + 2 * tpebs_event_size);
+	/* Note, no workload given so system wide is implied. */
 
 	assert(tpebs_cmd.pid == 0);
 	tpebs_cmd.argv = record_argv;
 	tpebs_cmd.out = -1;
 	ret = start_command(&tpebs_cmd);
-out:
-	free(record_argv);
+	zfree(&tpebs_cmd.argv);
 	return ret;
 }
 
-- 
2.49.0.395.g12beb8f557-goog