fix idr_find() locking
[linux-2.6.git] / kernel / cgroup_debug.c
1 /*
2  * kernel/ccontainer_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 struct cftype files[] =  {
66         {
67                 .name = "cgroup_refcount",
68                 .read_uint = cgroup_refcount_read,
69         },
70         {
71                 .name = "taskcount",
72                 .read_uint = taskcount_read,
73         },
74
75         {
76                 .name = "current_css_set",
77                 .read_uint = current_css_set_read,
78         },
79
80         {
81                 .name = "current_css_set_refcount",
82                 .read_uint = current_css_set_refcount_read,
83         },
84 };
85
86 static int debug_populate(struct cgroup_subsys *ss, struct cgroup *cont)
87 {
88         return cgroup_add_files(cont, ss, files, ARRAY_SIZE(files));
89 }
90
91 struct cgroup_subsys debug_subsys = {
92         .name = "debug",
93         .create = debug_create,
94         .destroy = debug_destroy,
95         .populate = debug_populate,
96         .subsys_id = debug_subsys_id,
97 };