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1 | // SPDX-License-Identifier: GPL-2.0 |
2 | /* | |
3 | * Miscellaneous cgroup controller | |
4 | * | |
5 | * Copyright 2020 Google LLC | |
6 | * Author: Vipin Sharma <vipinsh@google.com> | |
7 | */ | |
8 | ||
9 | #include <linux/limits.h> | |
10 | #include <linux/cgroup.h> | |
11 | #include <linux/errno.h> | |
12 | #include <linux/atomic.h> | |
13 | #include <linux/slab.h> | |
14 | #include <linux/misc_cgroup.h> | |
15 | ||
16 | #define MAX_STR "max" | |
17 | #define MAX_NUM ULONG_MAX | |
18 | ||
19 | /* Miscellaneous res name, keep it in sync with enum misc_res_type */ | |
20 | static const char *const misc_res_name[] = { | |
21 | }; | |
22 | ||
23 | /* Root misc cgroup */ | |
24 | static struct misc_cg root_cg; | |
25 | ||
26 | /* | |
27 | * Miscellaneous resources capacity for the entire machine. 0 capacity means | |
28 | * resource is not initialized or not present in the host. | |
29 | * | |
30 | * root_cg.max and capacity are independent of each other. root_cg.max can be | |
31 | * more than the actual capacity. We are using Limits resource distribution | |
32 | * model of cgroup for miscellaneous controller. | |
33 | */ | |
34 | static unsigned long misc_res_capacity[MISC_CG_RES_TYPES]; | |
35 | ||
36 | /** | |
37 | * parent_misc() - Get the parent of the passed misc cgroup. | |
38 | * @cgroup: cgroup whose parent needs to be fetched. | |
39 | * | |
40 | * Context: Any context. | |
41 | * Return: | |
42 | * * struct misc_cg* - Parent of the @cgroup. | |
43 | * * %NULL - If @cgroup is null or the passed cgroup does not have a parent. | |
44 | */ | |
45 | static struct misc_cg *parent_misc(struct misc_cg *cgroup) | |
46 | { | |
47 | return cgroup ? css_misc(cgroup->css.parent) : NULL; | |
48 | } | |
49 | ||
50 | /** | |
51 | * valid_type() - Check if @type is valid or not. | |
52 | * @type: misc res type. | |
53 | * | |
54 | * Context: Any context. | |
55 | * Return: | |
56 | * * true - If valid type. | |
57 | * * false - If not valid type. | |
58 | */ | |
59 | static inline bool valid_type(enum misc_res_type type) | |
60 | { | |
61 | return type >= 0 && type < MISC_CG_RES_TYPES; | |
62 | } | |
63 | ||
64 | /** | |
65 | * misc_cg_res_total_usage() - Get the current total usage of the resource. | |
66 | * @type: misc res type. | |
67 | * | |
68 | * Context: Any context. | |
69 | * Return: Current total usage of the resource. | |
70 | */ | |
71 | unsigned long misc_cg_res_total_usage(enum misc_res_type type) | |
72 | { | |
73 | if (valid_type(type)) | |
74 | return atomic_long_read(&root_cg.res[type].usage); | |
75 | ||
76 | return 0; | |
77 | } | |
78 | EXPORT_SYMBOL_GPL(misc_cg_res_total_usage); | |
79 | ||
80 | /** | |
81 | * misc_cg_set_capacity() - Set the capacity of the misc cgroup res. | |
82 | * @type: Type of the misc res. | |
83 | * @capacity: Supported capacity of the misc res on the host. | |
84 | * | |
85 | * If capacity is 0 then the charging a misc cgroup fails for that type. | |
86 | * | |
87 | * Context: Any context. | |
88 | * Return: | |
89 | * * %0 - Successfully registered the capacity. | |
90 | * * %-EINVAL - If @type is invalid. | |
91 | */ | |
92 | int misc_cg_set_capacity(enum misc_res_type type, unsigned long capacity) | |
93 | { | |
94 | if (!valid_type(type)) | |
95 | return -EINVAL; | |
96 | ||
97 | WRITE_ONCE(misc_res_capacity[type], capacity); | |
98 | return 0; | |
99 | } | |
100 | EXPORT_SYMBOL_GPL(misc_cg_set_capacity); | |
101 | ||
102 | /** | |
103 | * misc_cg_cancel_charge() - Cancel the charge from the misc cgroup. | |
104 | * @type: Misc res type in misc cg to cancel the charge from. | |
105 | * @cg: Misc cgroup to cancel charge from. | |
106 | * @amount: Amount to cancel. | |
107 | * | |
108 | * Context: Any context. | |
109 | */ | |
110 | static void misc_cg_cancel_charge(enum misc_res_type type, struct misc_cg *cg, | |
111 | unsigned long amount) | |
112 | { | |
113 | WARN_ONCE(atomic_long_add_negative(-amount, &cg->res[type].usage), | |
114 | "misc cgroup resource %s became less than 0", | |
115 | misc_res_name[type]); | |
116 | } | |
117 | ||
118 | /** | |
119 | * misc_cg_try_charge() - Try charging the misc cgroup. | |
120 | * @type: Misc res type to charge. | |
121 | * @cg: Misc cgroup which will be charged. | |
122 | * @amount: Amount to charge. | |
123 | * | |
124 | * Charge @amount to the misc cgroup. Caller must use the same cgroup during | |
125 | * the uncharge call. | |
126 | * | |
127 | * Context: Any context. | |
128 | * Return: | |
129 | * * %0 - If successfully charged. | |
130 | * * -EINVAL - If @type is invalid or misc res has 0 capacity. | |
131 | * * -EBUSY - If max limit will be crossed or total usage will be more than the | |
132 | * capacity. | |
133 | */ | |
134 | int misc_cg_try_charge(enum misc_res_type type, struct misc_cg *cg, | |
135 | unsigned long amount) | |
136 | { | |
137 | struct misc_cg *i, *j; | |
138 | int ret; | |
139 | struct misc_res *res; | |
140 | int new_usage; | |
141 | ||
142 | if (!(valid_type(type) && cg && READ_ONCE(misc_res_capacity[type]))) | |
143 | return -EINVAL; | |
144 | ||
145 | if (!amount) | |
146 | return 0; | |
147 | ||
148 | for (i = cg; i; i = parent_misc(i)) { | |
149 | res = &i->res[type]; | |
150 | ||
151 | new_usage = atomic_long_add_return(amount, &res->usage); | |
152 | if (new_usage > READ_ONCE(res->max) || | |
153 | new_usage > READ_ONCE(misc_res_capacity[type])) { | |
154 | if (!res->failed) { | |
155 | pr_info("cgroup: charge rejected by the misc controller for %s resource in ", | |
156 | misc_res_name[type]); | |
157 | pr_cont_cgroup_path(i->css.cgroup); | |
158 | pr_cont("\n"); | |
159 | res->failed = true; | |
160 | } | |
161 | ret = -EBUSY; | |
162 | goto err_charge; | |
163 | } | |
164 | } | |
165 | return 0; | |
166 | ||
167 | err_charge: | |
168 | for (j = cg; j != i; j = parent_misc(j)) | |
169 | misc_cg_cancel_charge(type, j, amount); | |
170 | misc_cg_cancel_charge(type, i, amount); | |
171 | return ret; | |
172 | } | |
173 | EXPORT_SYMBOL_GPL(misc_cg_try_charge); | |
174 | ||
175 | /** | |
176 | * misc_cg_uncharge() - Uncharge the misc cgroup. | |
177 | * @type: Misc res type which was charged. | |
178 | * @cg: Misc cgroup which will be uncharged. | |
179 | * @amount: Charged amount. | |
180 | * | |
181 | * Context: Any context. | |
182 | */ | |
183 | void misc_cg_uncharge(enum misc_res_type type, struct misc_cg *cg, | |
184 | unsigned long amount) | |
185 | { | |
186 | struct misc_cg *i; | |
187 | ||
188 | if (!(amount && valid_type(type) && cg)) | |
189 | return; | |
190 | ||
191 | for (i = cg; i; i = parent_misc(i)) | |
192 | misc_cg_cancel_charge(type, i, amount); | |
193 | } | |
194 | EXPORT_SYMBOL_GPL(misc_cg_uncharge); | |
195 | ||
196 | /** | |
197 | * misc_cg_max_show() - Show the misc cgroup max limit. | |
198 | * @sf: Interface file | |
199 | * @v: Arguments passed | |
200 | * | |
201 | * Context: Any context. | |
202 | * Return: 0 to denote successful print. | |
203 | */ | |
204 | static int misc_cg_max_show(struct seq_file *sf, void *v) | |
205 | { | |
206 | int i; | |
207 | struct misc_cg *cg = css_misc(seq_css(sf)); | |
208 | unsigned long max; | |
209 | ||
210 | for (i = 0; i < MISC_CG_RES_TYPES; i++) { | |
211 | if (READ_ONCE(misc_res_capacity[i])) { | |
212 | max = READ_ONCE(cg->res[i].max); | |
213 | if (max == MAX_NUM) | |
214 | seq_printf(sf, "%s max\n", misc_res_name[i]); | |
215 | else | |
216 | seq_printf(sf, "%s %lu\n", misc_res_name[i], | |
217 | max); | |
218 | } | |
219 | } | |
220 | ||
221 | return 0; | |
222 | } | |
223 | ||
224 | /** | |
225 | * misc_cg_max_write() - Update the maximum limit of the cgroup. | |
226 | * @of: Handler for the file. | |
227 | * @buf: Data from the user. It should be either "max", 0, or a positive | |
228 | * integer. | |
229 | * @nbytes: Number of bytes of the data. | |
230 | * @off: Offset in the file. | |
231 | * | |
232 | * User can pass data like: | |
233 | * echo sev 23 > misc.max, OR | |
234 | * echo sev max > misc.max | |
235 | * | |
236 | * Context: Any context. | |
237 | * Return: | |
238 | * * >= 0 - Number of bytes processed in the input. | |
239 | * * -EINVAL - If buf is not valid. | |
240 | * * -ERANGE - If number is bigger than the unsigned long capacity. | |
241 | */ | |
242 | static ssize_t misc_cg_max_write(struct kernfs_open_file *of, char *buf, | |
243 | size_t nbytes, loff_t off) | |
244 | { | |
245 | struct misc_cg *cg; | |
246 | unsigned long max; | |
247 | int ret = 0, i; | |
248 | enum misc_res_type type = MISC_CG_RES_TYPES; | |
249 | char *token; | |
250 | ||
251 | buf = strstrip(buf); | |
252 | token = strsep(&buf, " "); | |
253 | ||
254 | if (!token || !buf) | |
255 | return -EINVAL; | |
256 | ||
257 | for (i = 0; i < MISC_CG_RES_TYPES; i++) { | |
258 | if (!strcmp(misc_res_name[i], token)) { | |
259 | type = i; | |
260 | break; | |
261 | } | |
262 | } | |
263 | ||
264 | if (type == MISC_CG_RES_TYPES) | |
265 | return -EINVAL; | |
266 | ||
267 | if (!strcmp(MAX_STR, buf)) { | |
268 | max = MAX_NUM; | |
269 | } else { | |
270 | ret = kstrtoul(buf, 0, &max); | |
271 | if (ret) | |
272 | return ret; | |
273 | } | |
274 | ||
275 | cg = css_misc(of_css(of)); | |
276 | ||
277 | if (READ_ONCE(misc_res_capacity[type])) | |
278 | WRITE_ONCE(cg->res[type].max, max); | |
279 | else | |
280 | ret = -EINVAL; | |
281 | ||
282 | return ret ? ret : nbytes; | |
283 | } | |
284 | ||
285 | /** | |
286 | * misc_cg_current_show() - Show the current usage of the misc cgroup. | |
287 | * @sf: Interface file | |
288 | * @v: Arguments passed | |
289 | * | |
290 | * Context: Any context. | |
291 | * Return: 0 to denote successful print. | |
292 | */ | |
293 | static int misc_cg_current_show(struct seq_file *sf, void *v) | |
294 | { | |
295 | int i; | |
296 | unsigned long usage; | |
297 | struct misc_cg *cg = css_misc(seq_css(sf)); | |
298 | ||
299 | for (i = 0; i < MISC_CG_RES_TYPES; i++) { | |
300 | usage = atomic_long_read(&cg->res[i].usage); | |
301 | if (READ_ONCE(misc_res_capacity[i]) || usage) | |
302 | seq_printf(sf, "%s %lu\n", misc_res_name[i], usage); | |
303 | } | |
304 | ||
305 | return 0; | |
306 | } | |
307 | ||
308 | /** | |
309 | * misc_cg_capacity_show() - Show the total capacity of misc res on the host. | |
310 | * @sf: Interface file | |
311 | * @v: Arguments passed | |
312 | * | |
313 | * Only present in the root cgroup directory. | |
314 | * | |
315 | * Context: Any context. | |
316 | * Return: 0 to denote successful print. | |
317 | */ | |
318 | static int misc_cg_capacity_show(struct seq_file *sf, void *v) | |
319 | { | |
320 | int i; | |
321 | unsigned long cap; | |
322 | ||
323 | for (i = 0; i < MISC_CG_RES_TYPES; i++) { | |
324 | cap = READ_ONCE(misc_res_capacity[i]); | |
325 | if (cap) | |
326 | seq_printf(sf, "%s %lu\n", misc_res_name[i], cap); | |
327 | } | |
328 | ||
329 | return 0; | |
330 | } | |
331 | ||
332 | /* Misc cgroup interface files */ | |
333 | static struct cftype misc_cg_files[] = { | |
334 | { | |
335 | .name = "max", | |
336 | .write = misc_cg_max_write, | |
337 | .seq_show = misc_cg_max_show, | |
338 | .flags = CFTYPE_NOT_ON_ROOT, | |
339 | }, | |
340 | { | |
341 | .name = "current", | |
342 | .seq_show = misc_cg_current_show, | |
343 | .flags = CFTYPE_NOT_ON_ROOT, | |
344 | }, | |
345 | { | |
346 | .name = "capacity", | |
347 | .seq_show = misc_cg_capacity_show, | |
348 | .flags = CFTYPE_ONLY_ON_ROOT, | |
349 | }, | |
350 | {} | |
351 | }; | |
352 | ||
353 | /** | |
354 | * misc_cg_alloc() - Allocate misc cgroup. | |
355 | * @parent_css: Parent cgroup. | |
356 | * | |
357 | * Context: Process context. | |
358 | * Return: | |
359 | * * struct cgroup_subsys_state* - css of the allocated cgroup. | |
360 | * * ERR_PTR(-ENOMEM) - No memory available to allocate. | |
361 | */ | |
362 | static struct cgroup_subsys_state * | |
363 | misc_cg_alloc(struct cgroup_subsys_state *parent_css) | |
364 | { | |
365 | enum misc_res_type i; | |
366 | struct misc_cg *cg; | |
367 | ||
368 | if (!parent_css) { | |
369 | cg = &root_cg; | |
370 | } else { | |
371 | cg = kzalloc(sizeof(*cg), GFP_KERNEL); | |
372 | if (!cg) | |
373 | return ERR_PTR(-ENOMEM); | |
374 | } | |
375 | ||
376 | for (i = 0; i < MISC_CG_RES_TYPES; i++) { | |
377 | WRITE_ONCE(cg->res[i].max, MAX_NUM); | |
378 | atomic_long_set(&cg->res[i].usage, 0); | |
379 | } | |
380 | ||
381 | return &cg->css; | |
382 | } | |
383 | ||
384 | /** | |
385 | * misc_cg_free() - Free the misc cgroup. | |
386 | * @css: cgroup subsys object. | |
387 | * | |
388 | * Context: Any context. | |
389 | */ | |
390 | static void misc_cg_free(struct cgroup_subsys_state *css) | |
391 | { | |
392 | kfree(css_misc(css)); | |
393 | } | |
394 | ||
395 | /* Cgroup controller callbacks */ | |
396 | struct cgroup_subsys misc_cgrp_subsys = { | |
397 | .css_alloc = misc_cg_alloc, | |
398 | .css_free = misc_cg_free, | |
399 | .legacy_cftypes = misc_cg_files, | |
400 | .dfl_cftypes = misc_cg_files, | |
401 | }; |