Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
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>
authored by
Namhyung Kim
and committed by
Arnaldo Carvalho de Melo
7982a898
d46eec8e
+72
-61
+1
tools/lib/api/fs/Build
+1
tools/lib/api/fs/Build
+67
tools/lib/api/fs/cgroup.c
+67
tools/lib/api/fs/cgroup.c
···
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// SPDX-License-Identifier: GPL-2.0
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#include <linux/stringify.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <fcntl.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include "fs.h"
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int cgroupfs_find_mountpoint(char *buf, size_t maxlen, const char *subsys)
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{
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FILE *fp;
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char mountpoint[PATH_MAX + 1], tokens[PATH_MAX + 1], type[PATH_MAX + 1];
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char path_v1[PATH_MAX + 1], path_v2[PATH_MAX + 2], *path;
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char *token, *saved_ptr = NULL;
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fp = fopen("/proc/mounts", "r");
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if (!fp)
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return -1;
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/*
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* in order to handle split hierarchy, we need to scan /proc/mounts
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* and inspect every cgroupfs mount point to find one that has
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* perf_event subsystem
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*/
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path_v1[0] = '\0';
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path_v2[0] = '\0';
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while (fscanf(fp, "%*s %"__stringify(PATH_MAX)"s %"__stringify(PATH_MAX)"s %"
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__stringify(PATH_MAX)"s %*d %*d\n",
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mountpoint, type, tokens) == 3) {
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if (!path_v1[0] && !strcmp(type, "cgroup")) {
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token = strtok_r(tokens, ",", &saved_ptr);
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while (token != NULL) {
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if (subsys && !strcmp(token, subsys)) {
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strcpy(path_v1, mountpoint);
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break;
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}
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token = strtok_r(NULL, ",", &saved_ptr);
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}
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}
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if (!path_v2[0] && !strcmp(type, "cgroup2"))
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strcpy(path_v2, mountpoint);
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if (path_v1[0] && path_v2[0])
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break;
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}
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fclose(fp);
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if (path_v1[0])
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path = path_v1;
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else if (path_v2[0])
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path = path_v2;
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else
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return -1;
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if (strlen(path) < maxlen) {
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strcpy(buf, path);
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return 0;
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}
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return -1;
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}
+2
tools/lib/api/fs/fs.h
+2
tools/lib/api/fs/fs.h
···
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#undef FS
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int cgroupfs_find_mountpoint(char *buf, size_t maxlen, const char *subsys);
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int filename__read_int(const char *filename, int *value);
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int filename__read_ull(const char *filename, unsigned long long *value);
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int filename__read_xll(const char *filename, unsigned long long *value);
+2
-61
tools/perf/util/cgroup.c
+2
-61
tools/perf/util/cgroup.c
···
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#include "evsel.h"
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#include "cgroup.h"
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#include "evlist.h"
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#include <linux/stringify.h>
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#include <linux/zalloc.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <fcntl.h>
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#include <stdlib.h>
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#include <string.h>
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#include <api/fs/fs.h>
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int nr_cgroups;
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static int
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cgroupfs_find_mountpoint(char *buf, size_t maxlen)
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{
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FILE *fp;
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char mountpoint[PATH_MAX + 1], tokens[PATH_MAX + 1], type[PATH_MAX + 1];
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char path_v1[PATH_MAX + 1], path_v2[PATH_MAX + 2], *path;
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char *token, *saved_ptr = NULL;
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fp = fopen("/proc/mounts", "r");
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if (!fp)
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return -1;
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/*
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* in order to handle split hierarchy, we need to scan /proc/mounts
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* and inspect every cgroupfs mount point to find one that has
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* perf_event subsystem
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*/
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path_v1[0] = '\0';
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path_v2[0] = '\0';
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while (fscanf(fp, "%*s %"__stringify(PATH_MAX)"s %"__stringify(PATH_MAX)"s %"
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__stringify(PATH_MAX)"s %*d %*d\n",
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mountpoint, type, tokens) == 3) {
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if (!path_v1[0] && !strcmp(type, "cgroup")) {
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token = strtok_r(tokens, ",", &saved_ptr);
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while (token != NULL) {
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if (!strcmp(token, "perf_event")) {
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strcpy(path_v1, mountpoint);
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break;
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}
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token = strtok_r(NULL, ",", &saved_ptr);
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}
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}
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if (!path_v2[0] && !strcmp(type, "cgroup2"))
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strcpy(path_v2, mountpoint);
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if (path_v1[0] && path_v2[0])
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break;
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}
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fclose(fp);
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if (path_v1[0])
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path = path_v1;
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else if (path_v2[0])
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path = path_v2;
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else
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return -1;
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if (strlen(path) < maxlen) {
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strcpy(buf, path);
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return 0;
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}
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return -1;
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}
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static int open_cgroup(const char *name)
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{
···
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int fd;
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if (cgroupfs_find_mountpoint(mnt, PATH_MAX + 1))
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if (cgroupfs_find_mountpoint(mnt, PATH_MAX + 1, "perf_event"))
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return -1;
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scnprintf(path, PATH_MAX, "%s/%s", mnt, name);