tools lib api fs: Move cgroupsfs_find_mountpoint()

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.

Suggested-by: Jiri Olsa <jolsa@redhat.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: http://lore.kernel.org/lkml/20200127100031.1368732-1-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/lib/api/fs/Build b/tools/lib/api/fs/Build
index f4ed962..0f75b28 100644 (file)
--- 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 (file)
index 0000000..889a6eb
--- /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_find_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
+        * 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 (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 92d03b8..936edb9 100644 (file)
--- 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_find_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 4881d4a..5bc9d3b 100644 (file)
--- 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_find_mountpoint(mnt, PATH_MAX + 1, "perf_event"))
                return -1;
 
        scnprintf(path, PATH_MAX, "%s/%s", mnt, name);