kernel/cgroup/debug.c

   1 /*
   2  * Debug controller
   3  *
   4  * WARNING: This controller is for cgroup core debugging only.
   5  * Its interfaces are unstable and subject to changes at any time.
   6  */
   7 #include <linux/ctype.h>
   8 #include <linux/mm.h>
   9 #include <linux/slab.h>
  10
  11 #include "cgroup-internal.h"
  12
  13 static struct cgroup_subsys_state *
  14 debug_css_alloc(struct cgroup_subsys_state *parent_css)
  15 {
  16         struct cgroup_subsys_state *css = kzalloc(sizeof(*css), GFP_KERNEL);
  17
  18         if (!css)
  19                 return ERR_PTR(-ENOMEM);
  20
  21         return css;
  22 }
  23
  24 static void debug_css_free(struct cgroup_subsys_state *css)
  25 {
  26         kfree(css);
  27 }
  28
  29 /*
  30  * debug_taskcount_read - return the number of tasks in a cgroup.
  31  * @cgrp: the cgroup in question
  32  */
  33 static u64 debug_taskcount_read(struct cgroup_subsys_state *css,
  34                                 struct cftype *cft)
  35 {
  36         return cgroup_task_count(css->cgroup);
  37 }
  38
  39 static int current_css_set_read(struct seq_file *seq, void *v)
  40 {
  41         struct css_set *cset;
  42         struct cgroup_subsys *ss;
  43         struct cgroup_subsys_state *css;
  44         int i, refcnt;
  45
  46         mutex_lock(&cgroup_mutex);
  47         spin_lock_irq(&css_set_lock);
  48         rcu_read_lock();
  49         cset = rcu_dereference(current->cgroups);
  50         refcnt = refcount_read(&cset->refcount);
  51         seq_printf(seq, "css_set %pK %d", cset, refcnt);
  52         if (refcnt > cset->nr_tasks)
  53                 seq_printf(seq, " +%d", refcnt - cset->nr_tasks);
  54         seq_puts(seq, "\n");
  55
  56         /*
  57          * Print the css'es stored in the current css_set.
  58          */
  59         for_each_subsys(ss, i) {
  60                 css = cset->subsys[ss->id];
  61                 if (!css)
  62                         continue;
  63                 seq_printf(seq, "%2d: %-4s\t- %lx[%d]\n", ss->id, ss->name,
  64                           (unsigned long)css, css->id);
  65         }
  66         rcu_read_unlock();
  67         spin_unlock_irq(&css_set_lock);
  68         mutex_unlock(&cgroup_mutex);
  69         return 0;
  70 }
  71
  72 static u64 current_css_set_refcount_read(struct cgroup_subsys_state *css,
  73                                          struct cftype *cft)
  74 {
  75         u64 count;
  76
  77         rcu_read_lock();
  78         count = refcount_read(&task_css_set(current)->refcount);
  79         rcu_read_unlock();
  80         return count;
  81 }
  82
  83 static int current_css_set_cg_links_read(struct seq_file *seq, void *v)
  84 {
  85         struct cgrp_cset_link *link;
  86         struct css_set *cset;
  87         char *name_buf;
  88
  89         name_buf = kmalloc(NAME_MAX + 1, GFP_KERNEL);
  90         if (!name_buf)
  91                 return -ENOMEM;
  92
  93         spin_lock_irq(&css_set_lock);
  94         rcu_read_lock();
  95         cset = rcu_dereference(current->cgroups);
  96         list_for_each_entry(link, &cset->cgrp_links, cgrp_link) {
  97                 struct cgroup *c = link->cgrp;
  98
  99                 cgroup_name(c, name_buf, NAME_MAX + 1);
 100                 seq_printf(seq, "Root %d group %s\n",
 101                            c->root->hierarchy_id, name_buf);
 102         }
 103         rcu_read_unlock();
 104         spin_unlock_irq(&css_set_lock);
 105         kfree(name_buf);
 106         return 0;
 107 }
 108
 109 #define MAX_TASKS_SHOWN_PER_CSS 25
 110 static int cgroup_css_links_read(struct seq_file *seq, void *v)
 111 {
 112         struct cgroup_subsys_state *css = seq_css(seq);
 113         struct cgrp_cset_link *link;
 114         int dead_cnt = 0, extra_refs = 0;
 115
 116         spin_lock_irq(&css_set_lock);
 117         list_for_each_entry(link, &css->cgroup->cset_links, cset_link) {
 118                 struct css_set *cset = link->cset;
 119                 struct task_struct *task;
 120                 int count = 0;
 121                 int refcnt = refcount_read(&cset->refcount);
 122
 123                 seq_printf(seq, " %d", refcnt);
 124                 if (refcnt - cset->nr_tasks > 0) {
 125                         int extra = refcnt - cset->nr_tasks;
 126
 127                         seq_printf(seq, " +%d", extra);
 128                         /*
 129                          * Take out the one additional reference in
 130                          * init_css_set.
 131                          */
 132                         if (cset == &init_css_set)
 133                                 extra--;
 134                         extra_refs += extra;
 135                 }
 136                 seq_puts(seq, "\n");
 137
 138                 list_for_each_entry(task, &cset->tasks, cg_list) {
 139                         if (count++ <= MAX_TASKS_SHOWN_PER_CSS)
 140                                 seq_printf(seq, "  task %d\n",
 141                                            task_pid_vnr(task));
 142                 }
 143
 144                 list_for_each_entry(task, &cset->mg_tasks, cg_list) {
 145                         if (count++ <= MAX_TASKS_SHOWN_PER_CSS)
 146                                 seq_printf(seq, "  task %d\n",
 147                                            task_pid_vnr(task));
 148                 }
 149                 /* show # of overflowed tasks */
 150                 if (count > MAX_TASKS_SHOWN_PER_CSS)
 151                         seq_printf(seq, "  ... (%d)\n",
 152                                    count - MAX_TASKS_SHOWN_PER_CSS);
 153
 154                 if (cset->dead) {
 155                         seq_puts(seq, "    [dead]\n");
 156                         dead_cnt++;
 157                 }
 158
 159                 WARN_ON(count != cset->nr_tasks);
 160         }
 161         spin_unlock_irq(&css_set_lock);
 162
 163         if (!dead_cnt && !extra_refs)
 164                 return 0;
 165
 166         seq_puts(seq, "\n");
 167         if (extra_refs)
 168                 seq_printf(seq, "extra references = %d\n", extra_refs);
 169         if (dead_cnt)
 170                 seq_printf(seq, "dead css_sets = %d\n", dead_cnt);
 171
 172         return 0;
 173 }
 174
 175 static int cgroup_subsys_states_read(struct seq_file *seq, void *v)
 176 {
 177         struct cgroup *cgrp = seq_css(seq)->cgroup;
 178         struct cgroup_subsys *ss;
 179         struct cgroup_subsys_state *css;
 180         char pbuf[16];
 181         int i;
 182
 183         mutex_lock(&cgroup_mutex);
 184         for_each_subsys(ss, i) {
 185                 css = rcu_dereference_check(cgrp->subsys[ss->id], true);
 186                 if (!css)
 187                         continue;
 188
 189                 pbuf[0] = '\0';
 190
 191                 /* Show the parent CSS if applicable*/
 192                 if (css->parent)
 193                         snprintf(pbuf, sizeof(pbuf) - 1, " P=%d",
 194                                  css->parent->id);
 195                 seq_printf(seq, "%2d: %-4s\t- %lx[%d] %d%s\n", ss->id, ss->name,
 196                           (unsigned long)css, css->id,
 197                           atomic_read(&css->online_cnt), pbuf);
 198         }
 199         mutex_unlock(&cgroup_mutex);
 200         return 0;
 201 }
 202
 203 static int cgroup_masks_read(struct seq_file *seq, void *v)
 204 {
 205         struct cgroup *cgrp = seq_css(seq)->cgroup;
 206         struct cgroup_subsys *ss;
 207         int i, j;
 208         struct {
 209                 u16  *mask;
 210                 char *name;
 211         } mask_list[] = {
 212                 { &cgrp->subtree_control,  "subtree_control"  },
 213                 { &cgrp->subtree_ss_mask,  "subtree_ss_mask"  },
 214         };
 215
 216         mutex_lock(&cgroup_mutex);
 217         for (i = 0; i < ARRAY_SIZE(mask_list); i++) {
 218                 u16 mask = *mask_list[i].mask;
 219                 bool first = true;
 220
 221                 seq_printf(seq, "%-17s: ", mask_list[i].name);
 222                 for_each_subsys(ss, j) {
 223                         if (!(mask & (1 << ss->id)))
 224                                 continue;
 225                         if (!first)
 226                                 seq_puts(seq, ", ");
 227                         seq_puts(seq, ss->name);
 228                         first = false;
 229                 }
 230                 seq_putc(seq, '\n');
 231         }
 232
 233         mutex_unlock(&cgroup_mutex);
 234         return 0;
 235 }
 236
 237 static u64 releasable_read(struct cgroup_subsys_state *css, struct cftype *cft)
 238 {
 239         return (!cgroup_is_populated(css->cgroup) &&
 240                 !css_has_online_children(&css->cgroup->self));
 241 }
 242
 243 static struct cftype debug_files[] =  {
 244         {
 245                 .name = "taskcount",
 246                 .read_u64 = debug_taskcount_read,
 247         },
 248
 249         {
 250                 .name = "current_css_set",
 251                 .seq_show = current_css_set_read,
 252                 .flags = CFTYPE_ONLY_ON_ROOT,
 253         },
 254
 255         {
 256                 .name = "current_css_set_refcount",
 257                 .read_u64 = current_css_set_refcount_read,
 258                 .flags = CFTYPE_ONLY_ON_ROOT,
 259         },
 260
 261         {
 262                 .name = "current_css_set_cg_links",
 263                 .seq_show = current_css_set_cg_links_read,
 264                 .flags = CFTYPE_ONLY_ON_ROOT,
 265         },
 266
 267         {
 268                 .name = "cgroup_css_links",
 269                 .seq_show = cgroup_css_links_read,
 270         },
 271
 272         {
 273                 .name = "cgroup_subsys_states",
 274                 .seq_show = cgroup_subsys_states_read,
 275         },
 276
 277         {
 278                 .name = "cgroup_masks",
 279                 .seq_show = cgroup_masks_read,
 280         },
 281
 282         {
 283                 .name = "releasable",
 284                 .read_u64 = releasable_read,
 285         },
 286
 287         { }     /* terminate */
 288 };
 289
 290 struct cgroup_subsys debug_cgrp_subsys = {
 291         .css_alloc      = debug_css_alloc,
 292         .css_free       = debug_css_free,
 293         .legacy_cftypes = debug_files,
 294         .dfl_cftypes    = debug_files,
 295 };