perf tracepoint: Don't scan all tracepoints to test if one exists

In is_valid_tracepoint, rather than scanning
"/sys/kernel/tracing/events/*/*" skipping any path where
"/sys/kernel/tracing/events/*/*/id" doesn't exist, and then testing if
"*:*" matches the tracepoint name, just use the given tracepoint name
replace the ':' with '/' and see if the id file exists.

This turns a nested directory search into a single file available test.

Rather than return 1 for valid and 0 for invalid, return true and false.

Signed-off-by: Ian Rogers <irogers@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20240509153245.1990426-1-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/perf/util/tracepoint.c b/tools/perf/util/tracepoint.c
index 92dd8b455b9026aeb7126f186f8b74f8bd4bb162..95377ed5d87b09c4c192105280199e7d37d87f33 100644 (file)
--- a/tools/perf/util/tracepoint.c
+++ b/tools/perf/util/tracepoint.c
@@ -4,10 +4,12 @@
 #include <errno.h>
 #include <fcntl.h>
 #include <stdio.h>
+#include <stdlib.h>
 #include <sys/param.h>
 #include <unistd.h>
 
 #include <api/fs/tracing_path.h>
+#include "fncache.h"
 
 int tp_event_has_id(const char *dir_path, struct dirent *evt_dir)
 {
@@ -26,39 +28,25 @@ int tp_event_has_id(const char *dir_path, struct dirent *evt_dir)
 /*
  * Check whether event is in <debugfs_mount_point>/tracing/events
  */
-int is_valid_tracepoint(const char *event_string)
+bool is_valid_tracepoint(const char *event_string)
 {
-       DIR *sys_dir, *evt_dir;
-       struct dirent *sys_dirent, *evt_dirent;
-       char evt_path[MAXPATHLEN];
-       char *dir_path;
-
-       sys_dir = tracing_events__opendir();
-       if (!sys_dir)
-               return 0;
-
-       for_each_subsystem(sys_dir, sys_dirent) {
-               dir_path = get_events_file(sys_dirent->d_name);
-               if (!dir_path)
-                       continue;
-               evt_dir = opendir(dir_path);
-               if (!evt_dir)
-                       goto next;
-
-               for_each_event(dir_path, evt_dir, evt_dirent) {
-                       snprintf(evt_path, MAXPATHLEN, "%s:%s",
-                                sys_dirent->d_name, evt_dirent->d_name);
-                       if (!strcmp(evt_path, event_string)) {
-                               closedir(evt_dir);
-                               put_events_file(dir_path);
-                               closedir(sys_dir);
-                               return 1;
-                       }
-               }
-               closedir(evt_dir);
-next:
-               put_events_file(dir_path);
-       }
-       closedir(sys_dir);
-       return 0;
+       char *dst, *path = malloc(strlen(event_string) + 4); /* Space for "/id\0". */
+       bool have_file = false; /* Conservatively return false if memory allocation failed. */
+       const char *src;
+
+       if (!path)
+               return false;
+
+       /* Copy event_string replacing the ':' with '/'. */
+       for (src = event_string, dst = path; *src; src++, dst++)
+               *dst = (*src == ':') ? '/' : *src;
+       /* Add "/id\0". */
+       memcpy(dst, "/id", 4);
+
+       dst = get_events_file(path);
+       if (dst)
+               have_file = file_available(dst);
+       free(dst);
+       free(path);
+       return have_file;
 }

diff --git a/tools/perf/util/tracepoint.h b/tools/perf/util/tracepoint.h
index c4a110fe87d7be0b2ce4f26d3eca63ff1b4c5a59..65ccb01fc312e9d10688bde8e55784f6fbc96f05 100644 (file)
--- a/tools/perf/util/tracepoint.h
+++ b/tools/perf/util/tracepoint.h
@@ -4,6 +4,7 @@
 
 #include <dirent.h>
 #include <string.h>
+#include <stdbool.h>
 
 int tp_event_has_id(const char *dir_path, struct dirent *evt_dir);
 
@@ -20,6 +21,6 @@ int tp_event_has_id(const char *dir_path, struct dirent *evt_dir);
                    (strcmp(sys_dirent->d_name, ".")) &&        \
                    (strcmp(sys_dirent->d_name, "..")))
 
-int is_valid_tracepoint(const char *event_string);
+bool is_valid_tracepoint(const char *event_string);
 
 #endif /* __PERF_TRACEPOINT_H */