projects/linux·blob v4.14-rc2 · refs

382 lines · 8.3 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, threaded_csets = 0;
118
119 spin_lock_irq(&css_set_lock);
120
121 list_for_each_entry(link, &css->cgroup->cset_links, cset_link) {
122 struct css_set *cset = link->cset;
123 struct task_struct *task;
124 int count = 0;
125 int refcnt = refcount_read(&cset->refcount);
126
127 /*
128 * Print out the proc_cset and threaded_cset relationship
129 * and highlight difference between refcount and task_count.
130 */
131 seq_printf(seq, "css_set %pK", cset);
132 if (rcu_dereference_protected(cset->dom_cset, 1) != cset) {
133 threaded_csets++;
134 seq_printf(seq, "=>%pK", cset->dom_cset);
135 }
136 if (!list_empty(&cset->threaded_csets)) {
137 struct css_set *tcset;
138 int idx = 0;
139
140 list_for_each_entry(tcset, &cset->threaded_csets,
141 threaded_csets_node) {
142 seq_puts(seq, idx ? "," : "<=");
143 seq_printf(seq, "%pK", tcset);
144 idx++;
145 }
146 } else {
147 seq_printf(seq, " %d", refcnt);
148 if (refcnt - cset->nr_tasks > 0) {
149 int extra = refcnt - cset->nr_tasks;
150
151 seq_printf(seq, " +%d", extra);
152 /*
153 * Take out the one additional reference in
154 * init_css_set.
155 */
156 if (cset == &init_css_set)
157 extra--;
158 extra_refs += extra;
159 }
160 }
161 seq_puts(seq, "\n");
162
163 list_for_each_entry(task, &cset->tasks, cg_list) {
164 if (count++ <= MAX_TASKS_SHOWN_PER_CSS)
165 seq_printf(seq, " task %d\n",
166 task_pid_vnr(task));
167 }
168
169 list_for_each_entry(task, &cset->mg_tasks, cg_list) {
170 if (count++ <= MAX_TASKS_SHOWN_PER_CSS)
171 seq_printf(seq, " task %d\n",
172 task_pid_vnr(task));
173 }
174 /* show # of overflowed tasks */
175 if (count > MAX_TASKS_SHOWN_PER_CSS)
176 seq_printf(seq, " ... (%d)\n",
177 count - MAX_TASKS_SHOWN_PER_CSS);
178
179 if (cset->dead) {
180 seq_puts(seq, " [dead]\n");
181 dead_cnt++;
182 }
183
184 WARN_ON(count != cset->nr_tasks);
185 }
186 spin_unlock_irq(&css_set_lock);
187
188 if (!dead_cnt && !extra_refs && !threaded_csets)
189 return 0;
190
191 seq_puts(seq, "\n");
192 if (threaded_csets)
193 seq_printf(seq, "threaded css_sets = %d\n", threaded_csets);
194 if (extra_refs)
195 seq_printf(seq, "extra references = %d\n", extra_refs);
196 if (dead_cnt)
197 seq_printf(seq, "dead css_sets = %d\n", dead_cnt);
198
199 return 0;
200}
201
202static int cgroup_subsys_states_read(struct seq_file *seq, void *v)
203{
204 struct kernfs_open_file *of = seq->private;
205 struct cgroup *cgrp;
206 struct cgroup_subsys *ss;
207 struct cgroup_subsys_state *css;
208 char pbuf[16];
209 int i;
210
211 cgrp = cgroup_kn_lock_live(of->kn, false);
212 if (!cgrp)
213 return -ENODEV;
214
215 for_each_subsys(ss, i) {
216 css = rcu_dereference_check(cgrp->subsys[ss->id], true);
217 if (!css)
218 continue;
219
220 pbuf[0] = '\0';
221
222 /* Show the parent CSS if applicable*/
223 if (css->parent)
224 snprintf(pbuf, sizeof(pbuf) - 1, " P=%d",
225 css->parent->id);
226 seq_printf(seq, "%2d: %-4s\t- %lx[%d] %d%s\n", ss->id, ss->name,
227 (unsigned long)css, css->id,
228 atomic_read(&css->online_cnt), pbuf);
229 }
230
231 cgroup_kn_unlock(of->kn);
232 return 0;
233}
234
235static void cgroup_masks_read_one(struct seq_file *seq, const char *name,
236 u16 mask)
237{
238 struct cgroup_subsys *ss;
239 int ssid;
240 bool first = true;
241
242 seq_printf(seq, "%-17s: ", name);
243 for_each_subsys(ss, ssid) {
244 if (!(mask & (1 << ssid)))
245 continue;
246 if (!first)
247 seq_puts(seq, ", ");
248 seq_puts(seq, ss->name);
249 first = false;
250 }
251 seq_putc(seq, '\n');
252}
253
254static int cgroup_masks_read(struct seq_file *seq, void *v)
255{
256 struct kernfs_open_file *of = seq->private;
257 struct cgroup *cgrp;
258
259 cgrp = cgroup_kn_lock_live(of->kn, false);
260 if (!cgrp)
261 return -ENODEV;
262
263 cgroup_masks_read_one(seq, "subtree_control", cgrp->subtree_control);
264 cgroup_masks_read_one(seq, "subtree_ss_mask", cgrp->subtree_ss_mask);
265
266 cgroup_kn_unlock(of->kn);
267 return 0;
268}
269
270static u64 releasable_read(struct cgroup_subsys_state *css, struct cftype *cft)
271{
272 return (!cgroup_is_populated(css->cgroup) &&
273 !css_has_online_children(&css->cgroup->self));
274}
275
276static struct cftype debug_legacy_files[] = {
277 {
278 .name = "taskcount",
279 .read_u64 = debug_taskcount_read,
280 },
281
282 {
283 .name = "current_css_set",
284 .seq_show = current_css_set_read,
285 .flags = CFTYPE_ONLY_ON_ROOT,
286 },
287
288 {
289 .name = "current_css_set_refcount",
290 .read_u64 = current_css_set_refcount_read,
291 .flags = CFTYPE_ONLY_ON_ROOT,
292 },
293
294 {
295 .name = "current_css_set_cg_links",
296 .seq_show = current_css_set_cg_links_read,
297 .flags = CFTYPE_ONLY_ON_ROOT,
298 },
299
300 {
301 .name = "cgroup_css_links",
302 .seq_show = cgroup_css_links_read,
303 },
304
305 {
306 .name = "cgroup_subsys_states",
307 .seq_show = cgroup_subsys_states_read,
308 },
309
310 {
311 .name = "cgroup_masks",
312 .seq_show = cgroup_masks_read,
313 },
314
315 {
316 .name = "releasable",
317 .read_u64 = releasable_read,
318 },
319
320 { } /* terminate */
321};
322
323static struct cftype debug_files[] = {
324 {
325 .name = "taskcount",
326 .read_u64 = debug_taskcount_read,
327 },
328
329 {
330 .name = "current_css_set",
331 .seq_show = current_css_set_read,
332 .flags = CFTYPE_ONLY_ON_ROOT,
333 },
334
335 {
336 .name = "current_css_set_refcount",
337 .read_u64 = current_css_set_refcount_read,
338 .flags = CFTYPE_ONLY_ON_ROOT,
339 },
340
341 {
342 .name = "current_css_set_cg_links",
343 .seq_show = current_css_set_cg_links_read,
344 .flags = CFTYPE_ONLY_ON_ROOT,
345 },
346
347 {
348 .name = "css_links",
349 .seq_show = cgroup_css_links_read,
350 },
351
352 {
353 .name = "csses",
354 .seq_show = cgroup_subsys_states_read,
355 },
356
357 {
358 .name = "masks",
359 .seq_show = cgroup_masks_read,
360 },
361
362 { } /* terminate */
363};
364
365struct cgroup_subsys debug_cgrp_subsys = {
366 .css_alloc = debug_css_alloc,
367 .css_free = debug_css_free,
368 .legacy_cftypes = debug_legacy_files,
369};
370
371/*
372 * On v2, debug is an implicit controller enabled by "cgroup_debug" boot
373 * parameter.
374 */
375static int __init enable_cgroup_debug(char *str)
376{
377 debug_cgrp_subsys.dfl_cftypes = debug_files;
378 debug_cgrp_subsys.implicit_on_dfl = true;
379 debug_cgrp_subsys.threaded = true;
380 return 1;
381}
382__setup("cgroup_debug", enable_cgroup_debug);