kernel/cgroup_debug.c

   1 /*
   2  * kernel/cgroup_debug.c - Example cgroup subsystem that
   3  * exposes debug info
   4  *
   5  * Copyright (C) Google Inc, 2007
   6  *
   7  * Developed by Paul Menage (menage@google.com)
   8  *
   9  */
  10
  11 #include <linux/cgroup.h>
  12 #include <linux/fs.h>
  13 #include <linux/slab.h>
  14 #include <linux/rcupdate.h>
  15
  16 #include <asm/atomic.h>
  17
  18 static struct cgroup_subsys_state *debug_create(struct cgroup_subsys *ss,
  19                                                    struct cgroup *cont)
  20 {
  21         struct cgroup_subsys_state *css = kzalloc(sizeof(*css), GFP_KERNEL);
  22
  23         if (!css)
  24                 return ERR_PTR(-ENOMEM);
  25
  26         return css;
  27 }
  28
  29 static void debug_destroy(struct cgroup_subsys *ss, struct cgroup *cont)
  30 {
  31         kfree(cont->subsys[debug_subsys_id]);
  32 }
  33
  34 static u64 cgroup_refcount_read(struct cgroup *cont, struct cftype *cft)
  35 {
  36         return atomic_read(&cont->count);
  37 }
  38
  39 static u64 taskcount_read(struct cgroup *cont, struct cftype *cft)
  40 {
  41         u64 count;
  42
  43         cgroup_lock();
  44         count = cgroup_task_count(cont);
  45         cgroup_unlock();
  46         return count;
  47 }
  48
  49 static u64 current_css_set_read(struct cgroup *cont, struct cftype *cft)
  50 {
  51         return (u64)(long)current->cgroups;
  52 }
  53
  54 static u64 current_css_set_refcount_read(struct cgroup *cont,
  55                                            struct cftype *cft)
  56 {
  57         u64 count;
  58
  59         rcu_read_lock();
  60         count = atomic_read(&current->cgroups->ref.refcount);
  61         rcu_read_unlock();
  62         return count;
  63 }
  64
  65 static u64 releasable_read(struct cgroup *cgrp, struct cftype *cft)
  66 {
  67         return test_bit(CGRP_RELEASABLE, &cgrp->flags);
  68 }
  69
  70 static struct cftype files[] =  {
  71         {
  72                 .name = "cgroup_refcount",
  73                 .read_u64 = cgroup_refcount_read,
  74         },
  75         {
  76                 .name = "taskcount",
  77                 .read_u64 = taskcount_read,
  78         },
  79
  80         {
  81                 .name = "current_css_set",
  82                 .read_u64 = current_css_set_read,
  83         },
  84
  85         {
  86                 .name = "current_css_set_refcount",
  87                 .read_u64 = current_css_set_refcount_read,
  88         },
  89
  90         {
  91                 .name = "releasable",
  92                 .read_u64 = releasable_read,
  93         }
  94 };
  95
  96 static int debug_populate(struct cgroup_subsys *ss, struct cgroup *cont)
  97 {
  98         return cgroup_add_files(cont, ss, files, ARRAY_SIZE(files));
  99 }
 100
 101 struct cgroup_subsys debug_subsys = {
 102         .name = "debug",
 103         .create = debug_create,
 104         .destroy = debug_destroy,
 105         .populate = debug_populate,
 106         .subsys_id = debug_subsys_id,
 107 };