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b2441318 | 1 | // SPDX-License-Identifier: GPL-2.0 |
23b0be48 WL |
2 | /* |
3 | * Debug controller | |
4 | * | |
5 | * WARNING: This controller is for cgroup core debugging only. | |
6 | * Its interfaces are unstable and subject to changes at any time. | |
7 | */ | |
a28f8f5e WL |
8 | #include <linux/ctype.h> |
9 | #include <linux/mm.h> | |
10 | #include <linux/slab.h> | |
11 | ||
12 | #include "cgroup-internal.h" | |
13 | ||
14 | static struct cgroup_subsys_state * | |
15 | debug_css_alloc(struct cgroup_subsys_state *parent_css) | |
16 | { | |
17 | struct cgroup_subsys_state *css = kzalloc(sizeof(*css), GFP_KERNEL); | |
18 | ||
19 | if (!css) | |
20 | return ERR_PTR(-ENOMEM); | |
21 | ||
22 | return css; | |
23 | } | |
24 | ||
25 | static void debug_css_free(struct cgroup_subsys_state *css) | |
26 | { | |
27 | kfree(css); | |
28 | } | |
29 | ||
30 | /* | |
31 | * debug_taskcount_read - return the number of tasks in a cgroup. | |
32 | * @cgrp: the cgroup in question | |
33 | */ | |
34 | static u64 debug_taskcount_read(struct cgroup_subsys_state *css, | |
35 | struct cftype *cft) | |
36 | { | |
37 | return cgroup_task_count(css->cgroup); | |
38 | } | |
39 | ||
575313f4 | 40 | static int current_css_set_read(struct seq_file *seq, void *v) |
a28f8f5e | 41 | { |
b6053d40 | 42 | struct kernfs_open_file *of = seq->private; |
575313f4 WL |
43 | struct css_set *cset; |
44 | struct cgroup_subsys *ss; | |
45 | struct cgroup_subsys_state *css; | |
46 | int i, refcnt; | |
47 | ||
b6053d40 TH |
48 | if (!cgroup_kn_lock_live(of->kn, false)) |
49 | return -ENODEV; | |
50 | ||
575313f4 WL |
51 | spin_lock_irq(&css_set_lock); |
52 | rcu_read_lock(); | |
ddf7005f | 53 | cset = task_css_set(current); |
575313f4 WL |
54 | refcnt = refcount_read(&cset->refcount); |
55 | seq_printf(seq, "css_set %pK %d", cset, refcnt); | |
56 | if (refcnt > cset->nr_tasks) | |
57 | seq_printf(seq, " +%d", refcnt - cset->nr_tasks); | |
58 | seq_puts(seq, "\n"); | |
59 | ||
60 | /* | |
61 | * Print the css'es stored in the current css_set. | |
62 | */ | |
63 | for_each_subsys(ss, i) { | |
64 | css = cset->subsys[ss->id]; | |
65 | if (!css) | |
66 | continue; | |
1900da52 FH |
67 | seq_printf(seq, "%2d: %-4s\t- %p[%d]\n", ss->id, ss->name, |
68 | css, css->id); | |
575313f4 WL |
69 | } |
70 | rcu_read_unlock(); | |
71 | spin_unlock_irq(&css_set_lock); | |
b6053d40 | 72 | cgroup_kn_unlock(of->kn); |
575313f4 | 73 | return 0; |
a28f8f5e WL |
74 | } |
75 | ||
76 | static u64 current_css_set_refcount_read(struct cgroup_subsys_state *css, | |
77 | struct cftype *cft) | |
78 | { | |
79 | u64 count; | |
80 | ||
81 | rcu_read_lock(); | |
82 | count = refcount_read(&task_css_set(current)->refcount); | |
83 | rcu_read_unlock(); | |
84 | return count; | |
85 | } | |
86 | ||
87 | static int current_css_set_cg_links_read(struct seq_file *seq, void *v) | |
88 | { | |
89 | struct cgrp_cset_link *link; | |
90 | struct css_set *cset; | |
91 | char *name_buf; | |
92 | ||
93 | name_buf = kmalloc(NAME_MAX + 1, GFP_KERNEL); | |
94 | if (!name_buf) | |
95 | return -ENOMEM; | |
96 | ||
97 | spin_lock_irq(&css_set_lock); | |
98 | rcu_read_lock(); | |
ddf7005f | 99 | cset = task_css_set(current); |
a28f8f5e WL |
100 | list_for_each_entry(link, &cset->cgrp_links, cgrp_link) { |
101 | struct cgroup *c = link->cgrp; | |
102 | ||
103 | cgroup_name(c, name_buf, NAME_MAX + 1); | |
104 | seq_printf(seq, "Root %d group %s\n", | |
105 | c->root->hierarchy_id, name_buf); | |
106 | } | |
107 | rcu_read_unlock(); | |
108 | spin_unlock_irq(&css_set_lock); | |
109 | kfree(name_buf); | |
110 | return 0; | |
111 | } | |
112 | ||
113 | #define MAX_TASKS_SHOWN_PER_CSS 25 | |
114 | static int cgroup_css_links_read(struct seq_file *seq, void *v) | |
115 | { | |
116 | struct cgroup_subsys_state *css = seq_css(seq); | |
117 | struct cgrp_cset_link *link; | |
7a0cf0e7 | 118 | int dead_cnt = 0, extra_refs = 0, threaded_csets = 0; |
a28f8f5e WL |
119 | |
120 | spin_lock_irq(&css_set_lock); | |
7a0cf0e7 | 121 | |
a28f8f5e WL |
122 | list_for_each_entry(link, &css->cgroup->cset_links, cset_link) { |
123 | struct css_set *cset = link->cset; | |
124 | struct task_struct *task; | |
125 | int count = 0; | |
575313f4 | 126 | int refcnt = refcount_read(&cset->refcount); |
a28f8f5e | 127 | |
7a0cf0e7 WL |
128 | /* |
129 | * Print out the proc_cset and threaded_cset relationship | |
130 | * and highlight difference between refcount and task_count. | |
131 | */ | |
132 | seq_printf(seq, "css_set %pK", cset); | |
133 | if (rcu_dereference_protected(cset->dom_cset, 1) != cset) { | |
134 | threaded_csets++; | |
135 | seq_printf(seq, "=>%pK", cset->dom_cset); | |
136 | } | |
137 | if (!list_empty(&cset->threaded_csets)) { | |
138 | struct css_set *tcset; | |
139 | int idx = 0; | |
140 | ||
141 | list_for_each_entry(tcset, &cset->threaded_csets, | |
142 | threaded_csets_node) { | |
143 | seq_puts(seq, idx ? "," : "<="); | |
144 | seq_printf(seq, "%pK", tcset); | |
145 | idx++; | |
146 | } | |
147 | } else { | |
148 | seq_printf(seq, " %d", refcnt); | |
149 | if (refcnt - cset->nr_tasks > 0) { | |
150 | int extra = refcnt - cset->nr_tasks; | |
151 | ||
152 | seq_printf(seq, " +%d", extra); | |
153 | /* | |
154 | * Take out the one additional reference in | |
155 | * init_css_set. | |
156 | */ | |
157 | if (cset == &init_css_set) | |
158 | extra--; | |
159 | extra_refs += extra; | |
160 | } | |
575313f4 WL |
161 | } |
162 | seq_puts(seq, "\n"); | |
a28f8f5e WL |
163 | |
164 | list_for_each_entry(task, &cset->tasks, cg_list) { | |
575313f4 WL |
165 | if (count++ <= MAX_TASKS_SHOWN_PER_CSS) |
166 | seq_printf(seq, " task %d\n", | |
167 | task_pid_vnr(task)); | |
a28f8f5e WL |
168 | } |
169 | ||
170 | list_for_each_entry(task, &cset->mg_tasks, cg_list) { | |
575313f4 WL |
171 | if (count++ <= MAX_TASKS_SHOWN_PER_CSS) |
172 | seq_printf(seq, " task %d\n", | |
173 | task_pid_vnr(task)); | |
a28f8f5e | 174 | } |
575313f4 WL |
175 | /* show # of overflowed tasks */ |
176 | if (count > MAX_TASKS_SHOWN_PER_CSS) | |
177 | seq_printf(seq, " ... (%d)\n", | |
178 | count - MAX_TASKS_SHOWN_PER_CSS); | |
179 | ||
180 | if (cset->dead) { | |
181 | seq_puts(seq, " [dead]\n"); | |
182 | dead_cnt++; | |
183 | } | |
184 | ||
185 | WARN_ON(count != cset->nr_tasks); | |
a28f8f5e WL |
186 | } |
187 | spin_unlock_irq(&css_set_lock); | |
575313f4 | 188 | |
7a0cf0e7 | 189 | if (!dead_cnt && !extra_refs && !threaded_csets) |
575313f4 WL |
190 | return 0; |
191 | ||
192 | seq_puts(seq, "\n"); | |
7a0cf0e7 WL |
193 | if (threaded_csets) |
194 | seq_printf(seq, "threaded css_sets = %d\n", threaded_csets); | |
575313f4 WL |
195 | if (extra_refs) |
196 | seq_printf(seq, "extra references = %d\n", extra_refs); | |
197 | if (dead_cnt) | |
198 | seq_printf(seq, "dead css_sets = %d\n", dead_cnt); | |
199 | ||
200 | return 0; | |
201 | } | |
202 | ||
203 | static int cgroup_subsys_states_read(struct seq_file *seq, void *v) | |
204 | { | |
b6053d40 TH |
205 | struct kernfs_open_file *of = seq->private; |
206 | struct cgroup *cgrp; | |
575313f4 WL |
207 | struct cgroup_subsys *ss; |
208 | struct cgroup_subsys_state *css; | |
209 | char pbuf[16]; | |
210 | int i; | |
211 | ||
b6053d40 TH |
212 | cgrp = cgroup_kn_lock_live(of->kn, false); |
213 | if (!cgrp) | |
214 | return -ENODEV; | |
215 | ||
575313f4 WL |
216 | for_each_subsys(ss, i) { |
217 | css = rcu_dereference_check(cgrp->subsys[ss->id], true); | |
218 | if (!css) | |
219 | continue; | |
220 | ||
221 | pbuf[0] = '\0'; | |
222 | ||
223 | /* Show the parent CSS if applicable*/ | |
224 | if (css->parent) | |
225 | snprintf(pbuf, sizeof(pbuf) - 1, " P=%d", | |
226 | css->parent->id); | |
1900da52 FH |
227 | seq_printf(seq, "%2d: %-4s\t- %p[%d] %d%s\n", ss->id, ss->name, |
228 | css, css->id, | |
575313f4 WL |
229 | atomic_read(&css->online_cnt), pbuf); |
230 | } | |
b6053d40 TH |
231 | |
232 | cgroup_kn_unlock(of->kn); | |
575313f4 WL |
233 | return 0; |
234 | } | |
235 | ||
2866c0b4 TH |
236 | static void cgroup_masks_read_one(struct seq_file *seq, const char *name, |
237 | u16 mask) | |
575313f4 | 238 | { |
575313f4 | 239 | struct cgroup_subsys *ss; |
2866c0b4 TH |
240 | int ssid; |
241 | bool first = true; | |
575313f4 | 242 | |
2866c0b4 TH |
243 | seq_printf(seq, "%-17s: ", name); |
244 | for_each_subsys(ss, ssid) { | |
245 | if (!(mask & (1 << ssid))) | |
246 | continue; | |
247 | if (!first) | |
248 | seq_puts(seq, ", "); | |
249 | seq_puts(seq, ss->name); | |
250 | first = false; | |
575313f4 | 251 | } |
2866c0b4 TH |
252 | seq_putc(seq, '\n'); |
253 | } | |
575313f4 | 254 | |
2866c0b4 TH |
255 | static int cgroup_masks_read(struct seq_file *seq, void *v) |
256 | { | |
b6053d40 TH |
257 | struct kernfs_open_file *of = seq->private; |
258 | struct cgroup *cgrp; | |
259 | ||
260 | cgrp = cgroup_kn_lock_live(of->kn, false); | |
261 | if (!cgrp) | |
262 | return -ENODEV; | |
2866c0b4 | 263 | |
2866c0b4 TH |
264 | cgroup_masks_read_one(seq, "subtree_control", cgrp->subtree_control); |
265 | cgroup_masks_read_one(seq, "subtree_ss_mask", cgrp->subtree_ss_mask); | |
b6053d40 TH |
266 | |
267 | cgroup_kn_unlock(of->kn); | |
a28f8f5e WL |
268 | return 0; |
269 | } | |
270 | ||
271 | static u64 releasable_read(struct cgroup_subsys_state *css, struct cftype *cft) | |
272 | { | |
273 | return (!cgroup_is_populated(css->cgroup) && | |
274 | !css_has_online_children(&css->cgroup->self)); | |
275 | } | |
276 | ||
8cc38fa7 | 277 | static struct cftype debug_legacy_files[] = { |
a28f8f5e WL |
278 | { |
279 | .name = "taskcount", | |
280 | .read_u64 = debug_taskcount_read, | |
281 | }, | |
282 | ||
283 | { | |
284 | .name = "current_css_set", | |
575313f4 WL |
285 | .seq_show = current_css_set_read, |
286 | .flags = CFTYPE_ONLY_ON_ROOT, | |
a28f8f5e WL |
287 | }, |
288 | ||
289 | { | |
290 | .name = "current_css_set_refcount", | |
291 | .read_u64 = current_css_set_refcount_read, | |
575313f4 | 292 | .flags = CFTYPE_ONLY_ON_ROOT, |
a28f8f5e WL |
293 | }, |
294 | ||
295 | { | |
296 | .name = "current_css_set_cg_links", | |
297 | .seq_show = current_css_set_cg_links_read, | |
575313f4 | 298 | .flags = CFTYPE_ONLY_ON_ROOT, |
a28f8f5e WL |
299 | }, |
300 | ||
301 | { | |
302 | .name = "cgroup_css_links", | |
303 | .seq_show = cgroup_css_links_read, | |
304 | }, | |
305 | ||
575313f4 WL |
306 | { |
307 | .name = "cgroup_subsys_states", | |
308 | .seq_show = cgroup_subsys_states_read, | |
309 | }, | |
310 | ||
311 | { | |
312 | .name = "cgroup_masks", | |
313 | .seq_show = cgroup_masks_read, | |
314 | }, | |
315 | ||
a28f8f5e WL |
316 | { |
317 | .name = "releasable", | |
318 | .read_u64 = releasable_read, | |
319 | }, | |
320 | ||
321 | { } /* terminate */ | |
322 | }; | |
323 | ||
8cc38fa7 TH |
324 | static struct cftype debug_files[] = { |
325 | { | |
326 | .name = "taskcount", | |
327 | .read_u64 = debug_taskcount_read, | |
328 | }, | |
329 | ||
330 | { | |
331 | .name = "current_css_set", | |
332 | .seq_show = current_css_set_read, | |
333 | .flags = CFTYPE_ONLY_ON_ROOT, | |
334 | }, | |
335 | ||
336 | { | |
337 | .name = "current_css_set_refcount", | |
338 | .read_u64 = current_css_set_refcount_read, | |
339 | .flags = CFTYPE_ONLY_ON_ROOT, | |
340 | }, | |
341 | ||
342 | { | |
343 | .name = "current_css_set_cg_links", | |
344 | .seq_show = current_css_set_cg_links_read, | |
345 | .flags = CFTYPE_ONLY_ON_ROOT, | |
346 | }, | |
347 | ||
348 | { | |
349 | .name = "css_links", | |
350 | .seq_show = cgroup_css_links_read, | |
351 | }, | |
352 | ||
353 | { | |
354 | .name = "csses", | |
355 | .seq_show = cgroup_subsys_states_read, | |
356 | }, | |
357 | ||
358 | { | |
359 | .name = "masks", | |
360 | .seq_show = cgroup_masks_read, | |
361 | }, | |
362 | ||
363 | { } /* terminate */ | |
364 | }; | |
365 | ||
a28f8f5e | 366 | struct cgroup_subsys debug_cgrp_subsys = { |
575313f4 WL |
367 | .css_alloc = debug_css_alloc, |
368 | .css_free = debug_css_free, | |
8cc38fa7 | 369 | .legacy_cftypes = debug_legacy_files, |
a28f8f5e | 370 | }; |
8cc38fa7 TH |
371 | |
372 | /* | |
373 | * On v2, debug is an implicit controller enabled by "cgroup_debug" boot | |
374 | * parameter. | |
375 | */ | |
5cf8114d | 376 | void __init enable_debug_cgroup(void) |
8cc38fa7 TH |
377 | { |
378 | debug_cgrp_subsys.dfl_cftypes = debug_files; | |
379 | debug_cgrp_subsys.implicit_on_dfl = true; | |
8cfd8147 | 380 | debug_cgrp_subsys.threaded = true; |
8cc38fa7 | 381 | } |