Commit 7982a898 authored by Namhyung Kim's avatar Namhyung Kim Committed by Arnaldo Carvalho de Melo
Browse files

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: default avatarJiri Olsa <jolsa@redhat.com>
Signed-off-by: default avatarNamhyung 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: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent d46eec8e

tools/lib/api/fs/Build

+1 −0
Original line number Diff line number Diff line 
libapi-y += fs.o

libapi-y += tracing_path.o

libapi-y += cgroup.o

tools/lib/api/fs/cgroup.c

0 → 100644
+67 −0
Original line number Diff line number Diff line 
// 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;

}

tools/lib/api/fs/fs.h

+2 −0
Original line number Diff line number Diff line
@@ -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);

tools/perf/util/cgroup.c

+2 −61
Original line number Diff line number Diff line
@@ -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);

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