tools/perf/util/cgroup.c

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