perf pmu: Use relative path in setup_pmu_alias_list()

Likewise, x86 needs to traverse the PMU list to build alias.
Let's use the new helpers to use relative paths.
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Acked-by: Ian Rogers <irogers@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Leo Yan <leo.yan@linaro.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20230331202949.810326-2-namhyung@kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/arch/x86/util/pmu.c

@@ -71,7 +71,7 @@ static struct pmu_alias *pmu_alias__new(char *name, char *alias)
 
 static int setup_pmu_alias_list(void)
 {
-	char path[PATH_MAX];
+	int fd, dirfd;
 	DIR *dir;
 	struct dirent *dent;
 	struct pmu_alias *pmu_alias;
@@ -79,10 +79,11 @@ static int setup_pmu_alias_list(void)
 	FILE *file;
 	int ret = -ENOMEM;
 
-	if (!perf_pmu__event_source_devices_scnprintf(path, sizeof(path)))
+	dirfd = perf_pmu__event_source_devices_fd();
+	if (dirfd < 0)
 		return -1;
 
-	dir = opendir(path);
+	dir = fdopendir(dirfd);
 	if (!dir)
 		return -errno;
 
@@ -91,11 +92,11 @@ static int setup_pmu_alias_list(void)
 		    !strcmp(dent->d_name, ".."))
 			continue;
 
-		perf_pmu__pathname_scnprintf(path, sizeof(path), dent->d_name, "alias");
-		if (!file_available(path))
+		fd = perf_pmu__pathname_fd(dirfd, dent->d_name, "alias", O_RDONLY);
+		if (fd < 0)
 			continue;
 
-		file = fopen(path, "r");
+		file = fdopen(fd, "r");
 		if (!file)
 			continue;