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 #include <sys/types.h> 10 #include <sys/stat.h> 11 #include <fcntl.h> 12 13 int nr_cgroups; 14 15 static int 16 cgroupfs_find_mountpoint(char *buf, size_t maxlen) 17 { 18 FILE *fp; 19 char mountpoint[PATH_MAX + 1], tokens[PATH_MAX + 1], type[PATH_MAX + 1]; 20 char path_v1[PATH_MAX + 1], path_v2[PATH_MAX + 2], *path; 21 char *token, *saved_ptr = NULL; 22 23 fp = fopen("/proc/mounts", "r"); 24 if (!fp) 25 return -1; 26 27 /* 28 * in order to handle split hierarchy, we need to scan /proc/mounts 29 * and inspect every cgroupfs mount point to find one that has 30 * perf_event subsystem 31 */ 32 path_v1[0] = '\0'; 33 path_v2[0] = '\0'; 34 35 while (fscanf(fp, "%*s %"__stringify(PATH_MAX)"s %"__stringify(PATH_MAX)"s %" 36 __stringify(PATH_MAX)"s %*d %*d\n", 37 mountpoint, type, tokens) == 3) { 38 39 if (!path_v1[0] && !strcmp(type, "cgroup")) { 40 41 token = strtok_r(tokens, ",", &saved_ptr); 42 43 while (token != NULL) { 44 if (!strcmp(token, "perf_event")) { 45 strcpy(path_v1, mountpoint); 46 break; 47 } 48 token = strtok_r(NULL, ",", &saved_ptr); 49 } 50 } 51 52 if (!path_v2[0] && !strcmp(type, "cgroup2")) 53 strcpy(path_v2, mountpoint); 54 55 if (path_v1[0] && path_v2[0]) 56 break; 57 } 58 fclose(fp); 59 60 if (path_v1[0]) 61 path = path_v1; 62 else if (path_v2[0]) 63 path = path_v2; 64 else 65 return -1; 66 67 if (strlen(path) < maxlen) { 68 strcpy(buf, path); 69 return 0; 70 } 71 return -1; 72 } 73 74 static int open_cgroup(char *name) 75 { 76 char path[PATH_MAX + 1]; 77 char mnt[PATH_MAX + 1]; 78 int fd; 79 80 81 if (cgroupfs_find_mountpoint(mnt, PATH_MAX + 1)) 82 return -1; 83 84 snprintf(path, PATH_MAX, "%s/%s", mnt, name); 85 86 fd = open(path, O_RDONLY); 87 if (fd == -1) 88 fprintf(stderr, "no access to cgroup %s\n", path); 89 90 return fd; 91 } 92 93 static int add_cgroup(struct perf_evlist *evlist, char *str) 94 { 95 struct perf_evsel *counter; 96 struct cgroup *cgrp = NULL; 97 int n; 98 /* 99 * check if cgrp is already defined, if so we reuse it 100 */ 101 evlist__for_each_entry(evlist, counter) { 102 if (!counter->cgrp) 103 continue; 104 if (!strcmp(counter->cgrp->name, str)) { 105 cgrp = cgroup__get(counter->cgrp); 106 break; 107 } 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 } 135 136 cgroup__put(cgrp); 137 return -1; 138 found: 139 counter->cgrp = cgrp; 140 return 0; 141 } 142 143 static void cgroup__delete(struct cgroup *cgroup) 144 { 145 close(cgroup->fd); 146 zfree(&cgroup->name); 147 free(cgroup); 148 } 149 150 void cgroup__put(struct cgroup *cgrp) 151 { 152 if (cgrp && refcount_dec_and_test(&cgrp->refcnt)) { 153 cgroup__delete(cgrp); 154 } 155 } 156 157 struct cgroup *cgroup__get(struct cgroup *cgroup) 158 { 159 if (cgroup) 160 refcount_inc(&cgroup->refcnt); 161 return cgroup; 162 } 163 164 int parse_cgroups(const struct option *opt, const char *str, 165 int unset __maybe_unused) 166 { 167 struct perf_evlist *evlist = *(struct perf_evlist **)opt->value; 168 struct perf_evsel *counter; 169 struct cgroup *cgrp = NULL; 170 const char *p, *e, *eos = str + strlen(str); 171 char *s; 172 int ret, i; 173 174 if (list_empty(&evlist->entries)) { 175 fprintf(stderr, "must define events before cgroups\n"); 176 return -1; 177 } 178 179 for (;;) { 180 p = strchr(str, ','); 181 e = p ? p : eos; 182 183 /* allow empty cgroups, i.e., skip */ 184 if (e - str) { 185 /* termination added */ 186 s = strndup(str, e - str); 187 if (!s) 188 return -1; 189 ret = add_cgroup(evlist, s); 190 if (ret) { 191 free(s); 192 return -1; 193 } 194 } 195 /* nr_cgroups is increased een for empty cgroups */ 196 nr_cgroups++; 197 if (!p) 198 break; 199 str = p+1; 200 } 201 /* for the case one cgroup combine to multiple events */ 202 i = 0; 203 if (nr_cgroups == 1) { 204 evlist__for_each_entry(evlist, counter) { 205 if (i == 0) 206 cgrp = counter->cgrp; 207 else { 208 counter->cgrp = cgrp; 209 refcount_inc(&cgrp->refcnt); 210 } 211 i++; 212 } 213 } 214 return 0; 215 } 216