Re: [PATCH 1/9] perf list: Use relative path for tracepoint scan

[Arnaldo Carvalho de Melo]

Em Mon, Apr 03, 2023 at 06:59:10PM -0300, Arnaldo Carvalho de Melo escreveu:
> Em Fri, Mar 31, 2023 at 01:29:41PM -0700, Namhyung Kim escreveu:
> > Signed-off-by: Namhyung Kim <namhyung@xxxxxxxxxx>
> > ---
> >  tools/perf/util/print-events.c | 26 ++++++++++++++++++++------
> >  1 file changed, 20 insertions(+), 6 deletions(-)
> 
> Add to add this to fix on Alma Linux 8, and scandirat isn't being found
> on musl libc (Alpine Linux), probably we'll need some scaffolding...

About scandirat I'm adding the feature test below and this patch to the
patch that starts using scandirat():

diff --git a/tools/perf/util/print-events.c b/tools/perf/util/print-events.c
index 28aa0b9300253d0a..386b1ab0b60e1d93 100644
--- a/tools/perf/util/print-events.c
+++ b/tools/perf/util/print-events.c
@@ -58,11 +58,9 @@ static const struct event_symbol event_symbols_tool[PERF_TOOL_MAX] = {
 /*
  * Print the events from <debugfs_mount_point>/tracing/events
  */
-void print_tracepoint_events(const struct print_callbacks *print_cb, void *print_state)
+void print_tracepoint_events(const struct print_callbacks *print_cb __maybe_unused, void *print_state __maybe_unused)
 {
-	struct dirent **sys_namelist = NULL;
 	char *events_path = get_tracing_file("events");
-	int sys_items = tracing_events__scandir_alphasort(&sys_namelist);
 	int events_fd = open(events_path, O_PATH);
 
 	put_tracing_file(events_path);
@@ -71,6 +69,11 @@ void print_tracepoint_events(const struct print_callbacks *print_cb, void *print
 		return;
 	}
 
+#ifdef HAVE_SCANDIRAT_SUPPORT
+{
+	struct dirent **sys_namelist = NULL;
+	int sys_items = tracing_events__scandir_alphasort(&sys_namelist);
+
 	for (int i = 0; i < sys_items; i++) {
 		struct dirent *sys_dirent = sys_namelist[i];
 		struct dirent **evt_namelist = NULL;
@@ -120,7 +123,13 @@ void print_tracepoint_events(const struct print_callbacks *print_cb, void *print
 		close(dir_fd);
 		free(evt_namelist);
 	}
+
 	free(sys_namelist);
+}
+#else
+	printf("\nWARNING: Your libc doesn't have the scandir function, please ask its maintainers to implement it.\n"
+	       "         As a rough fallback, please do 'ls %s' to see the available tracepoint events.\n", events_path);
+#endif
 	close(events_fd);
 }