perf parse-events: Switch tracepoints to io_dir__readdir

Avoid DIR allocations when scanning sysfs by using io_dir for the
readdir implementation, that allocates about 1kb on the stack.

Signed-off-by: Ian Rogers <irogers@google.com>
Link: https://lore.kernel.org/r/20250222061015.303622-7-irogers@google.com
Signed-off-by: Namhyung Kim <namhyung@kernel.org>

diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c
index 6c36b98875bc919ca52a1caf5a21dc93b964d951..35e48fe56dfa34268f67438c5b8660cdcbafd577 100644 (file)
--- a/tools/perf/util/parse-events.c
+++ b/tools/perf/util/parse-events.c
@@ -17,6 +17,7 @@
 #include "strbuf.h"
 #include "debug.h"
 #include <api/fs/tracing_path.h>
+#include <api/io_dir.h>
 #include <perf/cpumap.h>
 #include <util/parse-events-bison.h>
 #include <util/parse-events-flex.h>
@@ -554,8 +555,8 @@ static int add_tracepoint_multi_event(struct parse_events_state *parse_state,
                                      struct parse_events_terms *head_config, YYLTYPE *loc)
 {
        char *evt_path;
-       struct dirent *evt_ent;
-       DIR *evt_dir;
+       struct io_dirent64 *evt_ent;
+       struct io_dir evt_dir;
        int ret = 0, found = 0;
 
        evt_path = get_events_file(sys_name);
@@ -563,14 +564,14 @@ static int add_tracepoint_multi_event(struct parse_events_state *parse_state,
                tracepoint_error(err, errno, sys_name, evt_name, loc->first_column);
                return -1;
        }
-       evt_dir = opendir(evt_path);
-       if (!evt_dir) {
+       io_dir__init(&evt_dir, open(evt_path, O_CLOEXEC | O_DIRECTORY | O_RDONLY));
+       if (evt_dir.dirfd < 0) {
                put_events_file(evt_path);
                tracepoint_error(err, errno, sys_name, evt_name, loc->first_column);
                return -1;
        }
 
-       while (!ret && (evt_ent = readdir(evt_dir))) {
+       while (!ret && (evt_ent = io_dir__readdir(&evt_dir))) {
                if (!strcmp(evt_ent->d_name, ".")
                    || !strcmp(evt_ent->d_name, "..")
                    || !strcmp(evt_ent->d_name, "enable")
@@ -592,7 +593,7 @@ static int add_tracepoint_multi_event(struct parse_events_state *parse_state,
        }
 
        put_events_file(evt_path);
-       closedir(evt_dir);
+       close(evt_dir.dirfd);
        return ret;
 }
 
@@ -615,17 +616,23 @@ static int add_tracepoint_multi_sys(struct parse_events_state *parse_state,
                                    struct parse_events_error *err,
                                    struct parse_events_terms *head_config, YYLTYPE *loc)
 {
-       struct dirent *events_ent;
-       DIR *events_dir;
+       struct io_dirent64 *events_ent;
+       struct io_dir events_dir;
        int ret = 0;
+       char *events_dir_path = get_tracing_file("events");
 
-       events_dir = tracing_events__opendir();
-       if (!events_dir) {
+       if (!events_dir_path) {
+               tracepoint_error(err, errno, sys_name, evt_name, loc->first_column);
+               return -1;
+       }
+       io_dir__init(&events_dir, open(events_dir_path, O_CLOEXEC | O_DIRECTORY | O_RDONLY));
+       put_events_file(events_dir_path);
+       if (events_dir.dirfd < 0) {
                tracepoint_error(err, errno, sys_name, evt_name, loc->first_column);
                return -1;
        }
 
-       while (!ret && (events_ent = readdir(events_dir))) {
+       while (!ret && (events_ent = io_dir__readdir(&events_dir))) {
                if (!strcmp(events_ent->d_name, ".")
                    || !strcmp(events_ent->d_name, "..")
                    || !strcmp(events_ent->d_name, "enable")
@@ -639,8 +646,7 @@ static int add_tracepoint_multi_sys(struct parse_events_state *parse_state,
                ret = add_tracepoint_event(parse_state, list, events_ent->d_name,
                                           evt_name, err, head_config, loc);
        }
-
-       closedir(events_dir);
+       close(events_dir.dirfd);
        return ret;
 }