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
debug_create(struct cgroup_subsys * ss,struct cgroup * cont)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
debug_destroy(struct cgroup_subsys * ss,struct cgroup * cont)29 static void debug_destroy(struct cgroup_subsys *ss, struct cgroup *cont)
30 {
31 kfree(cont->subsys[debug_subsys_id]);
32 }
33
cgroup_refcount_read(struct cgroup * cont,struct cftype * cft)34 static u64 cgroup_refcount_read(struct cgroup *cont, struct cftype *cft)
35 {
36 return atomic_read(&cont->count);
37 }
38
taskcount_read(struct cgroup * cont,struct cftype * cft)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
current_css_set_read(struct cgroup * cont,struct cftype * cft)49 static u64 current_css_set_read(struct cgroup *cont, struct cftype *cft)
50 {
51 return (u64)(long)current->cgroups;
52 }
53
current_css_set_refcount_read(struct cgroup * cont,struct cftype * cft)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(¤t->cgroups->refcount);
61 rcu_read_unlock();
62 return count;
63 }
64
releasable_read(struct cgroup * cgrp,struct cftype * cft)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
debug_populate(struct cgroup_subsys * ss,struct cgroup * cont)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 };
108