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         count = cgroup_task_count(cont);
  44         return count;
  45 }
  46
  47 static u64 current_css_set_read(struct cgroup *cont, struct cftype *cft)
  48 {
  49         return (u64)(long)current->cgroups;
  50 }
  51
  52 static u64 current_css_set_refcount_read(struct cgroup *cont,
  53                                            struct cftype *cft)
  54 {
  55         u64 count;
  56
  57         rcu_read_lock();
  58         count = atomic_read(&current->cgroups->refcount);
  59         rcu_read_unlock();
  60         return count;
  61 }
  62
  63 static u64 releasable_read(struct cgroup *cgrp, struct cftype *cft)
  64 {
  65         return test_bit(CGRP_RELEASABLE, &cgrp->flags);
  66 }
  67
  68 static struct cftype files[] =  {
  69         {
  70                 .name = "cgroup_refcount",
  71                 .read_u64 = cgroup_refcount_read,
  72         },
  73         {
  74                 .name = "taskcount",
  75                 .read_u64 = taskcount_read,
  76         },
  77
  78         {
  79                 .name = "current_css_set",
  80                 .read_u64 = current_css_set_read,
  81         },
  82
  83         {
  84                 .name = "current_css_set_refcount",
  85                 .read_u64 = current_css_set_refcount_read,
  86         },
  87
  88         {
  89                 .name = "releasable",
  90                 .read_u64 = releasable_read,
  91         },
  92 };
  93
  94 static int debug_populate(struct cgroup_subsys *ss, struct cgroup *cont)
  95 {
  96         return cgroup_add_files(cont, ss, files, ARRAY_SIZE(files));
  97 }
  98
  99 struct cgroup_subsys debug_subsys = {
 100         .name = "debug",
 101         .create = debug_create,
 102         .destroy = debug_destroy,
 103         .populate = debug_populate,
 104         .subsys_id = debug_subsys_id,
 105 };