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Subject[PATCH 03/10] tools lib api fs: Move cgroupsfs__mountpoint()
Date
Move it from tools/perf/util/cgroup.c as it can be used by other places.
Note that cgroup filesystem is different from others since it's usually
mounted separately (in v1) for each subsystem.

I just copied the code with a little modification to pass a name of
subsystem and renamed it to follow other APIs.

Suggested-by: Jiri Olsa <jolsa@redhat.com>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
---
tools/lib/api/fs/Build | 1 +
tools/lib/api/fs/cgroup.c | 67 +++++++++++++++++++++++++++++++++++++++
tools/lib/api/fs/fs.h | 2 ++
tools/perf/util/cgroup.c | 63 ++----------------------------------
4 files changed, 72 insertions(+), 61 deletions(-)
create mode 100644 tools/lib/api/fs/cgroup.c

diff --git a/tools/lib/api/fs/Build b/tools/lib/api/fs/Build
index f4ed9629ae85..0f75b28654de 100644
--- a/tools/lib/api/fs/Build
+++ b/tools/lib/api/fs/Build
@@ -1,2 +1,3 @@
libapi-y += fs.o
libapi-y += tracing_path.o
+libapi-y += cgroup.o
diff --git a/tools/lib/api/fs/cgroup.c b/tools/lib/api/fs/cgroup.c
new file mode 100644
index 000000000000..79676cada94a
--- /dev/null
+++ b/tools/lib/api/fs/cgroup.c
@@ -0,0 +1,67 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/stringify.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include "fs.h"
+
+int cgroupfs__mountpoint(char *buf, size_t maxlen, const char *subsys)
+{
+ FILE *fp;
+ char mountpoint[PATH_MAX + 1], tokens[PATH_MAX + 1], type[PATH_MAX + 1];
+ char path_v1[PATH_MAX + 1], path_v2[PATH_MAX + 2], *path;
+ char *token, *saved_ptr = NULL;
+
+ fp = fopen("/proc/mounts", "r");
+ if (!fp)
+ return -1;
+
+ /*
+ * in order to handle split hierarchy, we need to scan /proc/mounts
+ * and inspect every cgroupfs mount point to find one that has the
+ * given subsystem
+ */
+ path_v1[0] = '\0';
+ path_v2[0] = '\0';
+
+ while (fscanf(fp, "%*s %"__stringify(PATH_MAX)"s %"__stringify(PATH_MAX)"s %"
+ __stringify(PATH_MAX)"s %*d %*d\n",
+ mountpoint, type, tokens) == 3) {
+
+ if (!path_v1[0] && !strcmp(type, "cgroup")) {
+
+ token = strtok_r(tokens, ",", &saved_ptr);
+
+ while (token != NULL) {
+ if (!subsys || !strcmp(token, subsys)) {
+ strcpy(path_v1, mountpoint);
+ break;
+ }
+ token = strtok_r(NULL, ",", &saved_ptr);
+ }
+ }
+
+ if (!path_v2[0] && !strcmp(type, "cgroup2"))
+ strcpy(path_v2, mountpoint);
+
+ if (path_v1[0] && path_v2[0])
+ break;
+ }
+ fclose(fp);
+
+ if (path_v1[0])
+ path = path_v1;
+ else if (path_v2[0])
+ path = path_v2;
+ else
+ return -1;
+
+ if (strlen(path) < maxlen) {
+ strcpy(buf, path);
+ return 0;
+ }
+ return -1;
+}
diff --git a/tools/lib/api/fs/fs.h b/tools/lib/api/fs/fs.h
index 92d03b8396b1..07591ecbe39f 100644
--- a/tools/lib/api/fs/fs.h
+++ b/tools/lib/api/fs/fs.h
@@ -28,6 +28,8 @@ FS(bpf_fs)
#undef FS


+int cgroupfs__mountpoint(char *buf, size_t maxlen, const char *subsys);
+
int filename__read_int(const char *filename, int *value);
int filename__read_ull(const char *filename, unsigned long long *value);
int filename__read_xll(const char *filename, unsigned long long *value);
diff --git a/tools/perf/util/cgroup.c b/tools/perf/util/cgroup.c
index 4881d4af3381..12e466d1ec3b 100644
--- a/tools/perf/util/cgroup.c
+++ b/tools/perf/util/cgroup.c
@@ -3,75 +3,16 @@
#include "evsel.h"
#include "cgroup.h"
#include "evlist.h"
-#include <linux/stringify.h>
#include <linux/zalloc.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdlib.h>
#include <string.h>
+#include <api/fs/fs.h>

int nr_cgroups;

-static int
-cgroupfs_find_mountpoint(char *buf, size_t maxlen)
-{
- FILE *fp;
- char mountpoint[PATH_MAX + 1], tokens[PATH_MAX + 1], type[PATH_MAX + 1];
- char path_v1[PATH_MAX + 1], path_v2[PATH_MAX + 2], *path;
- char *token, *saved_ptr = NULL;
-
- fp = fopen("/proc/mounts", "r");
- if (!fp)
- return -1;
-
- /*
- * in order to handle split hierarchy, we need to scan /proc/mounts
- * and inspect every cgroupfs mount point to find one that has
- * perf_event subsystem
- */
- path_v1[0] = '\0';
- path_v2[0] = '\0';
-
- while (fscanf(fp, "%*s %"__stringify(PATH_MAX)"s %"__stringify(PATH_MAX)"s %"
- __stringify(PATH_MAX)"s %*d %*d\n",
- mountpoint, type, tokens) == 3) {
-
- if (!path_v1[0] && !strcmp(type, "cgroup")) {
-
- token = strtok_r(tokens, ",", &saved_ptr);
-
- while (token != NULL) {
- if (!strcmp(token, "perf_event")) {
- strcpy(path_v1, mountpoint);
- break;
- }
- token = strtok_r(NULL, ",", &saved_ptr);
- }
- }
-
- if (!path_v2[0] && !strcmp(type, "cgroup2"))
- strcpy(path_v2, mountpoint);
-
- if (path_v1[0] && path_v2[0])
- break;
- }
- fclose(fp);
-
- if (path_v1[0])
- path = path_v1;
- else if (path_v2[0])
- path = path_v2;
- else
- return -1;
-
- if (strlen(path) < maxlen) {
- strcpy(buf, path);
- return 0;
- }
- return -1;
-}
-
static int open_cgroup(const char *name)
{
char path[PATH_MAX + 1];
@@ -79,7 +20,7 @@ static int open_cgroup(const char *name)
int fd;


- if (cgroupfs_find_mountpoint(mnt, PATH_MAX + 1))
+ if (cgroupfs__mountpoint(mnt, PATH_MAX + 1, "perf_event"))
return -1;

scnprintf(path, PATH_MAX, "%s/%s", mnt, name);
--
2.25.0.265.gbab2e86ba0-goog
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