[PATCH v4 07/16] perf intel-tpebs: Inline get_perf_record_args

Ian Rogers
2025-04-09T06:11:06Z

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@google.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 e3bed86145b9..c4c818f32239 100644
--- a/tools/perf/util/intel-tpebs.c
+++ b/tools/perf/util/intel-tpebs.c
@@ -47,72 +47,53 @@ 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;
}

--
2.49.0.504.g3bcea36a83-goog