projects/linux·blob v4.13 · refs

357 lines · 7.6 KiB

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
13static struct cgroup_subsys_state *
14debug_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
24static 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 */
33static u64 debug_taskcount_read(struct cgroup_subsys_state *css,
34 struct cftype *cft)
35{
36 return cgroup_task_count(css->cgroup);
37}
38
39static int current_css_set_read(struct seq_file *seq, void *v)
40{
41 struct kernfs_open_file *of = seq->private;
42 struct css_set *cset;
43 struct cgroup_subsys *ss;
44 struct cgroup_subsys_state *css;
45 int i, refcnt;
46
47 if (!cgroup_kn_lock_live(of->kn, false))
48 return -ENODEV;
49
50 spin_lock_irq(&css_set_lock);
51 rcu_read_lock();
52 cset = rcu_dereference(current->cgroups);
53 refcnt = refcount_read(&cset->refcount);
54 seq_printf(seq, "css_set %pK %d", cset, refcnt);
55 if (refcnt > cset->nr_tasks)
56 seq_printf(seq, " +%d", refcnt - cset->nr_tasks);
57 seq_puts(seq, "\n");
58
59 /*
60 * Print the css'es stored in the current css_set.
61 */
62 for_each_subsys(ss, i) {
63 css = cset->subsys[ss->id];
64 if (!css)
65 continue;
66 seq_printf(seq, "%2d: %-4s\t- %lx[%d]\n", ss->id, ss->name,
67 (unsigned long)css, css->id);
68 }
69 rcu_read_unlock();
70 spin_unlock_irq(&css_set_lock);
71 cgroup_kn_unlock(of->kn);
72 return 0;
73}
74
75static u64 current_css_set_refcount_read(struct cgroup_subsys_state *css,
76 struct cftype *cft)
77{
78 u64 count;
79
80 rcu_read_lock();
81 count = refcount_read(&task_css_set(current)->refcount);
82 rcu_read_unlock();
83 return count;
84}
85
86static int current_css_set_cg_links_read(struct seq_file *seq, void *v)
87{
88 struct cgrp_cset_link *link;
89 struct css_set *cset;
90 char *name_buf;
91
92 name_buf = kmalloc(NAME_MAX + 1, GFP_KERNEL);
93 if (!name_buf)
94 return -ENOMEM;
95
96 spin_lock_irq(&css_set_lock);
97 rcu_read_lock();
98 cset = rcu_dereference(current->cgroups);
99 list_for_each_entry(link, &cset->cgrp_links, cgrp_link) {
100 struct cgroup *c = link->cgrp;
101
102 cgroup_name(c, name_buf, NAME_MAX + 1);
103 seq_printf(seq, "Root %d group %s\n",
104 c->root->hierarchy_id, name_buf);
105 }
106 rcu_read_unlock();
107 spin_unlock_irq(&css_set_lock);
108 kfree(name_buf);
109 return 0;
110}
111
112#define MAX_TASKS_SHOWN_PER_CSS 25
113static int cgroup_css_links_read(struct seq_file *seq, void *v)
114{
115 struct cgroup_subsys_state *css = seq_css(seq);
116 struct cgrp_cset_link *link;
117 int dead_cnt = 0, extra_refs = 0;
118
119 spin_lock_irq(&css_set_lock);
120 list_for_each_entry(link, &css->cgroup->cset_links, cset_link) {
121 struct css_set *cset = link->cset;
122 struct task_struct *task;
123 int count = 0;
124 int refcnt = refcount_read(&cset->refcount);
125
126 seq_printf(seq, " %d", refcnt);
127 if (refcnt - cset->nr_tasks > 0) {
128 int extra = refcnt - cset->nr_tasks;
129
130 seq_printf(seq, " +%d", extra);
131 /*
132 * Take out the one additional reference in
133 * init_css_set.
134 */
135 if (cset == &init_css_set)
136 extra--;
137 extra_refs += extra;
138 }
139 seq_puts(seq, "\n");
140
141 list_for_each_entry(task, &cset->tasks, cg_list) {
142 if (count++ <= MAX_TASKS_SHOWN_PER_CSS)
143 seq_printf(seq, " task %d\n",
144 task_pid_vnr(task));
145 }
146
147 list_for_each_entry(task, &cset->mg_tasks, cg_list) {
148 if (count++ <= MAX_TASKS_SHOWN_PER_CSS)
149 seq_printf(seq, " task %d\n",
150 task_pid_vnr(task));
151 }
152 /* show # of overflowed tasks */
153 if (count > MAX_TASKS_SHOWN_PER_CSS)
154 seq_printf(seq, " ... (%d)\n",
155 count - MAX_TASKS_SHOWN_PER_CSS);
156
157 if (cset->dead) {
158 seq_puts(seq, " [dead]\n");
159 dead_cnt++;
160 }
161
162 WARN_ON(count != cset->nr_tasks);
163 }
164 spin_unlock_irq(&css_set_lock);
165
166 if (!dead_cnt && !extra_refs)
167 return 0;
168
169 seq_puts(seq, "\n");
170 if (extra_refs)
171 seq_printf(seq, "extra references = %d\n", extra_refs);
172 if (dead_cnt)
173 seq_printf(seq, "dead css_sets = %d\n", dead_cnt);
174
175 return 0;
176}
177
178static int cgroup_subsys_states_read(struct seq_file *seq, void *v)
179{
180 struct kernfs_open_file *of = seq->private;
181 struct cgroup *cgrp;
182 struct cgroup_subsys *ss;
183 struct cgroup_subsys_state *css;
184 char pbuf[16];
185 int i;
186
187 cgrp = cgroup_kn_lock_live(of->kn, false);
188 if (!cgrp)
189 return -ENODEV;
190
191 for_each_subsys(ss, i) {
192 css = rcu_dereference_check(cgrp->subsys[ss->id], true);
193 if (!css)
194 continue;
195
196 pbuf[0] = '\0';
197
198 /* Show the parent CSS if applicable*/
199 if (css->parent)
200 snprintf(pbuf, sizeof(pbuf) - 1, " P=%d",
201 css->parent->id);
202 seq_printf(seq, "%2d: %-4s\t- %lx[%d] %d%s\n", ss->id, ss->name,
203 (unsigned long)css, css->id,
204 atomic_read(&css->online_cnt), pbuf);
205 }
206
207 cgroup_kn_unlock(of->kn);
208 return 0;
209}
210
211static void cgroup_masks_read_one(struct seq_file *seq, const char *name,
212 u16 mask)
213{
214 struct cgroup_subsys *ss;
215 int ssid;
216 bool first = true;
217
218 seq_printf(seq, "%-17s: ", name);
219 for_each_subsys(ss, ssid) {
220 if (!(mask & (1 << ssid)))
221 continue;
222 if (!first)
223 seq_puts(seq, ", ");
224 seq_puts(seq, ss->name);
225 first = false;
226 }
227 seq_putc(seq, '\n');
228}
229
230static int cgroup_masks_read(struct seq_file *seq, void *v)
231{
232 struct kernfs_open_file *of = seq->private;
233 struct cgroup *cgrp;
234
235 cgrp = cgroup_kn_lock_live(of->kn, false);
236 if (!cgrp)
237 return -ENODEV;
238
239 cgroup_masks_read_one(seq, "subtree_control", cgrp->subtree_control);
240 cgroup_masks_read_one(seq, "subtree_ss_mask", cgrp->subtree_ss_mask);
241
242 cgroup_kn_unlock(of->kn);
243 return 0;
244}
245
246static u64 releasable_read(struct cgroup_subsys_state *css, struct cftype *cft)
247{
248 return (!cgroup_is_populated(css->cgroup) &&
249 !css_has_online_children(&css->cgroup->self));
250}
251
252static struct cftype debug_legacy_files[] = {
253 {
254 .name = "taskcount",
255 .read_u64 = debug_taskcount_read,
256 },
257
258 {
259 .name = "current_css_set",
260 .seq_show = current_css_set_read,
261 .flags = CFTYPE_ONLY_ON_ROOT,
262 },
263
264 {
265 .name = "current_css_set_refcount",
266 .read_u64 = current_css_set_refcount_read,
267 .flags = CFTYPE_ONLY_ON_ROOT,
268 },
269
270 {
271 .name = "current_css_set_cg_links",
272 .seq_show = current_css_set_cg_links_read,
273 .flags = CFTYPE_ONLY_ON_ROOT,
274 },
275
276 {
277 .name = "cgroup_css_links",
278 .seq_show = cgroup_css_links_read,
279 },
280
281 {
282 .name = "cgroup_subsys_states",
283 .seq_show = cgroup_subsys_states_read,
284 },
285
286 {
287 .name = "cgroup_masks",
288 .seq_show = cgroup_masks_read,
289 },
290
291 {
292 .name = "releasable",
293 .read_u64 = releasable_read,
294 },
295
296 { } /* terminate */
297};
298
299static struct cftype debug_files[] = {
300 {
301 .name = "taskcount",
302 .read_u64 = debug_taskcount_read,
303 },
304
305 {
306 .name = "current_css_set",
307 .seq_show = current_css_set_read,
308 .flags = CFTYPE_ONLY_ON_ROOT,
309 },
310
311 {
312 .name = "current_css_set_refcount",
313 .read_u64 = current_css_set_refcount_read,
314 .flags = CFTYPE_ONLY_ON_ROOT,
315 },
316
317 {
318 .name = "current_css_set_cg_links",
319 .seq_show = current_css_set_cg_links_read,
320 .flags = CFTYPE_ONLY_ON_ROOT,
321 },
322
323 {
324 .name = "css_links",
325 .seq_show = cgroup_css_links_read,
326 },
327
328 {
329 .name = "csses",
330 .seq_show = cgroup_subsys_states_read,
331 },
332
333 {
334 .name = "masks",
335 .seq_show = cgroup_masks_read,
336 },
337
338 { } /* terminate */
339};
340
341struct cgroup_subsys debug_cgrp_subsys = {
342 .css_alloc = debug_css_alloc,
343 .css_free = debug_css_free,
344 .legacy_cftypes = debug_legacy_files,
345};
346
347/*
348 * On v2, debug is an implicit controller enabled by "cgroup_debug" boot
349 * parameter.
350 */
351static int __init enable_cgroup_debug(char *str)
352{
353 debug_cgrp_subsys.dfl_cftypes = debug_files;
354 debug_cgrp_subsys.implicit_on_dfl = true;
355 return 1;
356}
357__setup("cgroup_debug", enable_cgroup_debug);