1 // SPDX-License-Identifier: GPL-2.0 2 #include "util.h" 3 #include "../perf.h" 4 #include <subcmd/parse-options.h> 5 #include "evsel.h" 6 #include "cgroup.h" 7 #include "evlist.h" 8 #include <linux/stringify.h> 9 10 int nr_cgroups; 11 12 static int 13 cgroupfs_find_mountpoint(char *buf, size_t maxlen) 14 { 15 FILE *fp; 16 char mountpoint[PATH_MAX + 1], tokens[PATH_MAX + 1], type[PATH_MAX + 1]; 17 char path_v1[PATH_MAX + 1], path_v2[PATH_MAX + 2], *path; 18 char *token, *saved_ptr = NULL; 19 20 fp = fopen("/proc/mounts", "r"); 21 if (!fp) 22 return -1; 23 24 /* 25 * in order to handle split hierarchy, we need to scan /proc/mounts 26 * and inspect every cgroupfs mount point to find one that has 27 * perf_event subsystem 28 */ 29 path_v1[0] = '\0'; 30 path_v2[0] = '\0'; 31 32 while (fscanf(fp, "%*s %"__stringify(PATH_MAX)"s %"__stringify(PATH_MAX)"s %" 33 __stringify(PATH_MAX)"s %*d %*d\n", 34 mountpoint, type, tokens) == 3) { 35 36 if (!path_v1[0] && !strcmp(type, "cgroup")) { 37 38 token = strtok_r(tokens, ",", &saved_ptr); 39 40 while (token != NULL) { 41 if (!strcmp(token, "perf_event")) { 42 strcpy(path_v1, mountpoint); 43 break; 44 } 45 token = strtok_r(NULL, ",", &saved_ptr); 46 } 47 } 48 49 if (!path_v2[0] && !strcmp(type, "cgroup2")) 50 strcpy(path_v2, mountpoint); 51 52 if (path_v1[0] && path_v2[0]) 53 break; 54 } 55 fclose(fp); 56 57 if (path_v1[0]) 58 path = path_v1; 59 else if (path_v2[0]) 60 path = path_v2; 61 else 62 return -1; 63 64 if (strlen(path) < maxlen) { 65 strcpy(buf, path); 66 return 0; 67 } 68 return -1; 69 } 70 71 static int open_cgroup(char *name) 72 { 73 char path[PATH_MAX + 1]; 74 char mnt[PATH_MAX + 1]; 75 int fd; 76 77 78 if (cgroupfs_find_mountpoint(mnt, PATH_MAX + 1)) 79 return -1; 80 81 snprintf(path, PATH_MAX, "%s/%s", mnt, name); 82 83 fd = open(path, O_RDONLY); 84 if (fd == -1) 85 fprintf(stderr, "no access to cgroup %s\n", path); 86 87 return fd; 88 } 89 90 static int add_cgroup(struct perf_evlist *evlist, char *str) 91 { 92 struct perf_evsel *counter; 93 struct cgroup_sel *cgrp = NULL; 94 int n; 95 /* 96 * check if cgrp is already defined, if so we reuse it 97 */ 98 evlist__for_each_entry(evlist, counter) { 99 cgrp = counter->cgrp; 100 if (!cgrp) 101 continue; 102 if (!strcmp(cgrp->name, str)) { 103 refcount_inc(&cgrp->refcnt); 104 break; 105 } 106 107 cgrp = NULL; 108 } 109 110 if (!cgrp) { 111 cgrp = zalloc(sizeof(*cgrp)); 112 if (!cgrp) 113 return -1; 114 115 cgrp->name = str; 116 refcount_set(&cgrp->refcnt, 1); 117 118 cgrp->fd = open_cgroup(str); 119 if (cgrp->fd == -1) { 120 free(cgrp); 121 return -1; 122 } 123 } 124 125 /* 126 * find corresponding event 127 * if add cgroup N, then need to find event N 128 */ 129 n = 0; 130 evlist__for_each_entry(evlist, counter) { 131 if (n == nr_cgroups) 132 goto found; 133 n++; 134 } 135 if (refcount_dec_and_test(&cgrp->refcnt)) 136 free(cgrp); 137 138 return -1; 139 found: 140 counter->cgrp = cgrp; 141 return 0; 142 } 143 144 void close_cgroup(struct cgroup_sel *cgrp) 145 { 146 if (cgrp && refcount_dec_and_test(&cgrp->refcnt)) { 147 close(cgrp->fd); 148 zfree(&cgrp->name); 149 free(cgrp); 150 } 151 } 152 153 int parse_cgroups(const struct option *opt __maybe_unused, const char *str, 154 int unset __maybe_unused) 155 { 156 struct perf_evlist *evlist = *(struct perf_evlist **)opt->value; 157 const char *p, *e, *eos = str + strlen(str); 158 char *s; 159 int ret; 160 161 if (list_empty(&evlist->entries)) { 162 fprintf(stderr, "must define events before cgroups\n"); 163 return -1; 164 } 165 166 for (;;) { 167 p = strchr(str, ','); 168 e = p ? p : eos; 169 170 /* allow empty cgroups, i.e., skip */ 171 if (e - str) { 172 /* termination added */ 173 s = strndup(str, e - str); 174 if (!s) 175 return -1; 176 ret = add_cgroup(evlist, s); 177 if (ret) { 178 free(s); 179 return -1; 180 } 181 } 182 /* nr_cgroups is increased een for empty cgroups */ 183 nr_cgroups++; 184 if (!p) 185 break; 186 str = p+1; 187 } 188 return 0; 189 } 190