Re: [PATCH 1/4] perf pmu: Add function to check if a pmu file exists

Hi Arnaldo, thanks for the review

On 10/05/2022 17:41, Arnaldo Carvalho de Melo wrote:

Em Wed, May 04, 2022 at 04:02:12PM +0100, German Gomez escreveu:

...

Add a utility function perf_pmu__file_exists() to check if a given pmu file exists in the sysfs filesystem.

While reviewing this I noticed:

int perf_pmu__caps_parse(struct perf_pmu *pmu) { struct stat st; char caps_path[PATH_MAX]; const char *sysfs = sysfs__mountpoint(); DIR *caps_dir; struct dirent *evt_ent; int nr_caps = 0;

    if (!sysfs)
            return -1;

    snprintf(caps_path, PATH_MAX,
             "%s" EVENT_SOURCE_DEVICE_PATH "%s/caps", sysfs, pmu->name);

    if (stat(caps_path, &st) < 0)
            return 0;       /* no error if caps does not exist */

---

Shouldn't we introduce a:

const int perf__pmu_pathname_scnprintf(struct perf_pmu *pmu, char *pathname, size_t size, char *filename) {

return scnprintf(pathname, size, "%s" EVENT_SOURCE_DEVICE_PATH "%s/%s", sysfs, pmu->name, filename); }

And use in your perf_pmu__file_exists() and in the other places where this open coded pattern appears?

I agree. If nobody else has done it before me, I will send the refactor in the next respin.

Thanks, German

I'm waiting for reviews for the ARM specific bits.

• Arnaldo

...

Signed-off-by: German Gomez german.gomez@arm.com

tools/perf/util/pmu.c | 17 +++++++++++++++++ tools/perf/util/pmu.h | 2 ++ 2 files changed, 19 insertions(+)

diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c index 9a1c7e63e663..9479e9a4da54 100644 --- a/tools/perf/util/pmu.c +++ b/tools/perf/util/pmu.c @@ -1854,6 +1854,23 @@ int perf_pmu__scan_file(struct perf_pmu *pmu, const char *name, const char *fmt, return ret; } +bool perf_pmu__file_exists(struct perf_pmu *pmu, const char *name) +{

• char path[PATH_MAX];
• struct stat statbuf;
• const char *sysfs = sysfs__mountpoint();
• if (!sysfs)

• return false;
  

• snprintf(path, PATH_MAX,

•  "%s" EVENT_SOURCE_DEVICE_PATH "%s/%s", sysfs, pmu->name, name);
  

• if (!file_available(path))

• return false;
  

• return stat(path, &statbuf) == 0;

+}

static int perf_pmu__new_caps(struct list_head *list, char *name, char *value) { struct perf_pmu_caps *caps = zalloc(sizeof(*caps)); diff --git a/tools/perf/util/pmu.h b/tools/perf/util/pmu.h index 541889fa9f9c..ab728eaf13b6 100644 --- a/tools/perf/util/pmu.h +++ b/tools/perf/util/pmu.h @@ -120,6 +120,8 @@ bool pmu_have_event(const char *pname, const char *name); int perf_pmu__scan_file(struct perf_pmu *pmu, const char *name, const char *fmt, ...) __scanf(3, 4); +bool perf_pmu__file_exists(struct perf_pmu *pmu, const char *name);

int perf_pmu__test(void); struct perf_event_attr *perf_pmu__get_default_config(struct perf_pmu *pmu); -- 2.25.1