tools/perf/util/cgroup.c

   1 #include "util.h"
   2 #include "../perf.h"
   3 #include "parse-options.h"
   4 #include "evsel.h"
   5 #include "cgroup.h"
   6 #include "debugfs.h" /* MAX_PATH, STR() */
   7 #include "evlist.h"
   8
   9 int nr_cgroups;
  10
  11 static int
  12 cgroupfs_find_mountpoint(char *buf, size_t maxlen)
  13 {
  14         FILE *fp;
  15         char mountpoint[MAX_PATH+1], tokens[MAX_PATH+1], type[MAX_PATH+1];
  16         char *token, *saved_ptr = NULL;
  17         int found = 0;
  18
  19         fp = fopen("/proc/mounts", "r");
  20         if (!fp)
  21                 return -1;
  22
  23         /*
  24          * in order to handle split hierarchy, we need to scan /proc/mounts
  25          * and inspect every cgroupfs mount point to find one that has
  26          * perf_event subsystem
  27          */
  28         while (fscanf(fp, "%*s %"STR(MAX_PATH)"s %"STR(MAX_PATH)"s %"
  29                                 STR(MAX_PATH)"s %*d %*d\n",
  30                                 mountpoint, type, tokens) == 3) {
  31
  32                 if (!strcmp(type, "cgroup")) {
  33
  34                         token = strtok_r(tokens, ",", &saved_ptr);
  35
  36                         while (token != NULL) {
  37                                 if (!strcmp(token, "perf_event")) {
  38                                         found = 1;
  39                                         break;
  40                                 }
  41                                 token = strtok_r(NULL, ",", &saved_ptr);
  42                         }
  43                 }
  44                 if (found)
  45                         break;
  46         }
  47         fclose(fp);
  48         if (!found)
  49                 return -1;
  50
  51         if (strlen(mountpoint) < maxlen) {
  52                 strcpy(buf, mountpoint);
  53                 return 0;
  54         }
  55         return -1;
  56 }
  57
  58 static int open_cgroup(char *name)
  59 {
  60         char path[MAX_PATH+1];
  61         char mnt[MAX_PATH+1];
  62         int fd;
  63
  64
  65         if (cgroupfs_find_mountpoint(mnt, MAX_PATH+1))
  66                 return -1;
  67
  68         snprintf(path, MAX_PATH, "%s/%s", mnt, name);
  69
  70         fd = open(path, O_RDONLY);
  71         if (fd == -1)
  72                 fprintf(stderr, "no access to cgroup %s\n", path);
  73
  74         return fd;
  75 }
  76
  77 static int add_cgroup(struct perf_evlist *evlist, char *str)
  78 {
  79         struct perf_evsel *counter;
  80         struct cgroup_sel *cgrp = NULL;
  81         int n;
  82         /*
  83          * check if cgrp is already defined, if so we reuse it
  84          */
  85         list_for_each_entry(counter, &evlist->entries, node) {
  86                 cgrp = counter->cgrp;
  87                 if (!cgrp)
  88                         continue;
  89                 if (!strcmp(cgrp->name, str))
  90                         break;
  91
  92                 cgrp = NULL;
  93         }
  94
  95         if (!cgrp) {
  96                 cgrp = zalloc(sizeof(*cgrp));
  97                 if (!cgrp)
  98                         return -1;
  99
 100                 cgrp->name = str;
 101
 102                 cgrp->fd = open_cgroup(str);
 103                 if (cgrp->fd == -1) {
 104                         free(cgrp);
 105                         return -1;
 106                 }
 107         }
 108
 109         /*
 110          * find corresponding event
 111          * if add cgroup N, then need to find event N
 112          */
 113         n = 0;
 114         list_for_each_entry(counter, &evlist->entries, node) {
 115                 if (n == nr_cgroups)
 116                         goto found;
 117                 n++;
 118         }
 119         if (cgrp->refcnt == 0)
 120                 free(cgrp);
 121
 122         return -1;
 123 found:
 124         cgrp->refcnt++;
 125         counter->cgrp = cgrp;
 126         return 0;
 127 }
 128
 129 void close_cgroup(struct cgroup_sel *cgrp)
 130 {
 131         if (!cgrp)
 132                 return;
 133
 134         /* XXX: not reentrant */
 135         if (--cgrp->refcnt == 0) {
 136                 close(cgrp->fd);
 137                 free(cgrp->name);
 138                 free(cgrp);
 139         }
 140 }
 141
 142 int parse_cgroups(const struct option *opt __used, const char *str,
 143                   int unset __used)
 144 {
 145         struct perf_evlist *evlist = *(struct perf_evlist **)opt->value;
 146         const char *p, *e, *eos = str + strlen(str);
 147         char *s;
 148         int ret;
 149
 150         if (list_empty(&evlist->entries)) {
 151                 fprintf(stderr, "must define events before cgroups\n");
 152                 return -1;
 153         }
 154
 155         for (;;) {
 156                 p = strchr(str, ',');
 157                 e = p ? p : eos;
 158
 159                 /* allow empty cgroups, i.e., skip */
 160                 if (e - str) {
 161                         /* termination added */
 162                         s = strndup(str, e - str);
 163                         if (!s)
 164                                 return -1;
 165                         ret = add_cgroup(evlist, s);
 166                         if (ret) {
 167                                 free(s);
 168                                 return -1;
 169                         }
 170                 }
 171                 /* nr_cgroups is increased een for empty cgroups */
 172                 nr_cgroups++;
 173                 if (!p)
 174                         break;
 175                 str = p+1;
 176         }
 177         return 0;
 178 }