perf intel-tpebs: Ensure events are opened, factor out finding

Factor out finding an tpebs_retire_lat from an evsel.

Don't blindly return when ignoring an open request, which happens after
the first open request, ensure the event was started on a fork of perf
record.

Reviewed-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Ian Rogers <irogers@google.com>
Tested-by: Weilin Wang <weilin.wang@intel.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Alexandre Torgue <alexandre.torgue@foss.st.com>
Cc: Andreas Färber <afaerber@suse.de>
Cc: Caleb Biggers <caleb.biggers@intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Maxime Coquelin <mcoquelin.stm32@gmail.com>
Cc: Perry Taylor <perry.taylor@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Falcon <thomas.falcon@intel.com>
Link: https://lore.kernel.org/r/20250414174134.3095492-9-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/perf/util/intel-tpebs.c b/tools/perf/util/intel-tpebs.c
index c4c818f32239c354c73f33d5a1a1a7bc37d771d3..e42f3ec39a64c2e6a4a08550982be2e0cf6cd375 100644 (file)
--- a/tools/perf/util/intel-tpebs.c
+++ b/tools/perf/util/intel-tpebs.c
@@ -45,6 +45,8 @@ struct tpebs_retire_lat {
        int sum;
        /* Average of retire_latency, val = sum / count */
        double val;
+       /* Has the event been sent to perf record? */
+       bool started;
 };
 
 static int evsel__tpebs_start_perf_record(struct evsel *evsel, int control_fd[], int ack_fd[])
@@ -94,6 +96,9 @@ static int evsel__tpebs_start_perf_record(struct evsel *evsel, int control_fd[],
        tpebs_cmd.out = -1;
        ret = start_command(&tpebs_cmd);
        zfree(&tpebs_cmd.argv);
+       list_for_each_entry(t, &tpebs_results, nd)
+               t->started = true;
+
        return ret;
 }
 
@@ -214,6 +219,19 @@ static struct tpebs_retire_lat *tpebs_retire_lat__new(struct evsel *evsel)
        return result;
 }
 
+static struct tpebs_retire_lat *tpebs_retire_lat__find(struct evsel *evsel)
+{
+       struct tpebs_retire_lat *t;
+
+       list_for_each_entry(t, &tpebs_results, nd) {
+               if (t->tpebs_name == evsel->name ||
+                   !strcmp(t->tpebs_name, evsel->name) ||
+                   (evsel->metric_id && !strcmp(t->tpebs_name, evsel->metric_id)))
+                       return t;
+       }
+       return NULL;
+}
+
 /**
  * evsel__tpebs_prepare - create tpebs data structures ready for opening.
  * @evsel: retire_latency evsel, all evsels on its list will be prepared.
@@ -221,16 +239,11 @@ static struct tpebs_retire_lat *tpebs_retire_lat__new(struct evsel *evsel)
 static int evsel__tpebs_prepare(struct evsel *evsel)
 {
        struct evsel *pos;
-       struct tpebs_retire_lat *tpebs_event;
-
-       list_for_each_entry(tpebs_event, &tpebs_results, nd) {
-               if (!strcmp(tpebs_event->tpebs_name, evsel->name)) {
-                       /*
-                        * evsel, or an identically named one, was already
-                        * prepared.
-                        */
-                       return 0;
-               }
+       struct tpebs_retire_lat *tpebs_event = tpebs_retire_lat__find(evsel);
+
+       if (tpebs_event) {
+               /* evsel, or an identically named one, was already prepared. */
+               return 0;
        }
        tpebs_event = tpebs_retire_lat__new(evsel);
        if (!tpebs_event)
@@ -262,12 +275,19 @@ int evsel__tpebs_open(struct evsel *evsel)
 {
        int ret;
 
-       /*
-        * We should only run tpebs_start when tpebs_recording is enabled.
-        * And we should only run it once with all the required events.
-        */
-       if (tpebs_cmd.pid != 0 || !tpebs_recording)
+       /* We should only run tpebs_start when tpebs_recording is enabled. */
+       if (!tpebs_recording)
                return 0;
+       /* Only start the events once. */
+       if (tpebs_cmd.pid != 0) {
+               struct tpebs_retire_lat *t = tpebs_retire_lat__find(evsel);
+
+               if (!t || !t->started) {
+                       /* Fail, as the event wasn't started. */
+                       return -EBUSY;
+               }
+               return 0;
+       }
 
        ret = evsel__tpebs_prepare(evsel);
        if (ret)
@@ -352,7 +372,6 @@ out:
 int tpebs_set_evsel(struct evsel *evsel, int cpu_map_idx, int thread)
 {
        __u64 val;
-       bool found = false;
        struct tpebs_retire_lat *t;
        struct perf_counts_values *count;
 
@@ -367,19 +386,13 @@ int tpebs_set_evsel(struct evsel *evsel, int cpu_map_idx, int thread)
        tpebs_stop();
        count = perf_counts(evsel->counts, cpu_map_idx, thread);
 
-       list_for_each_entry(t, &tpebs_results, nd) {
-               if (t->tpebs_name == evsel->name ||
-                   (evsel->metric_id && !strcmp(t->tpebs_name, evsel->metric_id))) {
-                       found = true;
-                       break;
-               }
-       }
+       t = tpebs_retire_lat__find(evsel);
 
        /* Set ena and run to non-zero */
        count->ena = count->run = 1;
        count->lost = 0;
 
-       if (!found) {
+       if (!t) {
                /*
                 * Set default value or 0 when retire_latency for this event is
                 * not found from sampling data (record_tpebs not set or 0