bsr: fix build problem with bsr_class static cleanup
[platform/kernel/linux-rpi.git] / kernel / cgroup / debug.c
1 // SPDX-License-Identifier: GPL-2.0
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  */
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
40 static int current_css_set_read(struct seq_file *seq, void *v)
41 {
42         struct kernfs_open_file *of = seq->private;
43         struct css_set *cset;
44         struct cgroup_subsys *ss;
45         struct cgroup_subsys_state *css;
46         int i, refcnt;
47
48         if (!cgroup_kn_lock_live(of->kn, false))
49                 return -ENODEV;
50
51         spin_lock_irq(&css_set_lock);
52         rcu_read_lock();
53         cset = task_css_set(current);
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;
67                 seq_printf(seq, "%2d: %-4s\t- %p[%d]\n", ss->id, ss->name,
68                           css, css->id);
69         }
70         rcu_read_unlock();
71         spin_unlock_irq(&css_set_lock);
72         cgroup_kn_unlock(of->kn);
73         return 0;
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();
99         cset = task_css_set(current);
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;
118         int dead_cnt = 0, extra_refs = 0, threaded_csets = 0;
119
120         spin_lock_irq(&css_set_lock);
121
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;
126                 int refcnt = refcount_read(&cset->refcount);
127
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                         }
161                 }
162                 seq_puts(seq, "\n");
163
164                 list_for_each_entry(task, &cset->tasks, cg_list) {
165                         if (count++ <= MAX_TASKS_SHOWN_PER_CSS)
166                                 seq_printf(seq, "  task %d\n",
167                                            task_pid_vnr(task));
168                 }
169
170                 list_for_each_entry(task, &cset->mg_tasks, cg_list) {
171                         if (count++ <= MAX_TASKS_SHOWN_PER_CSS)
172                                 seq_printf(seq, "  task %d\n",
173                                            task_pid_vnr(task));
174                 }
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);
186         }
187         spin_unlock_irq(&css_set_lock);
188
189         if (!dead_cnt && !extra_refs && !threaded_csets)
190                 return 0;
191
192         seq_puts(seq, "\n");
193         if (threaded_csets)
194                 seq_printf(seq, "threaded css_sets = %d\n", threaded_csets);
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 {
205         struct kernfs_open_file *of = seq->private;
206         struct cgroup *cgrp;
207         struct cgroup_subsys *ss;
208         struct cgroup_subsys_state *css;
209         char pbuf[16];
210         int i;
211
212         cgrp = cgroup_kn_lock_live(of->kn, false);
213         if (!cgrp)
214                 return -ENODEV;
215
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);
227                 seq_printf(seq, "%2d: %-4s\t- %p[%d] %d%s\n", ss->id, ss->name,
228                           css, css->id,
229                           atomic_read(&css->online_cnt), pbuf);
230         }
231
232         cgroup_kn_unlock(of->kn);
233         return 0;
234 }
235
236 static void cgroup_masks_read_one(struct seq_file *seq, const char *name,
237                                   u16 mask)
238 {
239         struct cgroup_subsys *ss;
240         int ssid;
241         bool first = true;
242
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;
251         }
252         seq_putc(seq, '\n');
253 }
254
255 static int cgroup_masks_read(struct seq_file *seq, void *v)
256 {
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;
263
264         cgroup_masks_read_one(seq, "subtree_control", cgrp->subtree_control);
265         cgroup_masks_read_one(seq, "subtree_ss_mask", cgrp->subtree_ss_mask);
266
267         cgroup_kn_unlock(of->kn);
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
277 static struct cftype debug_legacy_files[] =  {
278         {
279                 .name = "taskcount",
280                 .read_u64 = debug_taskcount_read,
281         },
282
283         {
284                 .name = "current_css_set",
285                 .seq_show = current_css_set_read,
286                 .flags = CFTYPE_ONLY_ON_ROOT,
287         },
288
289         {
290                 .name = "current_css_set_refcount",
291                 .read_u64 = current_css_set_refcount_read,
292                 .flags = CFTYPE_ONLY_ON_ROOT,
293         },
294
295         {
296                 .name = "current_css_set_cg_links",
297                 .seq_show = current_css_set_cg_links_read,
298                 .flags = CFTYPE_ONLY_ON_ROOT,
299         },
300
301         {
302                 .name = "cgroup_css_links",
303                 .seq_show = cgroup_css_links_read,
304         },
305
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
316         {
317                 .name = "releasable",
318                 .read_u64 = releasable_read,
319         },
320
321         { }     /* terminate */
322 };
323
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
366 struct cgroup_subsys debug_cgrp_subsys = {
367         .css_alloc      = debug_css_alloc,
368         .css_free       = debug_css_free,
369         .legacy_cftypes = debug_legacy_files,
370 };
371
372 /*
373  * On v2, debug is an implicit controller enabled by "cgroup_debug" boot
374  * parameter.
375  */
376 void __init enable_debug_cgroup(void)
377 {
378         debug_cgrp_subsys.dfl_cftypes = debug_files;
379         debug_cgrp_subsys.implicit_on_dfl = true;
380         debug_cgrp_subsys.threaded = true;
381 }