1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * kernel/power/wakelock.c
4 *
5 * User space wakeup sources support.
6 *
7 * Copyright (C) 2012 Rafael J. Wysocki <rjw@sisk.pl>
8 *
9 * This code is based on the analogous interface allowing user space to
10 * manipulate wakelocks on Android.
11 */
12
13 #include <linux/capability.h>
14 #include <linux/ctype.h>
15 #include <linux/device.h>
16 #include <linux/err.h>
17 #include <linux/hrtimer.h>
18 #include <linux/list.h>
19 #include <linux/rbtree.h>
20 #include <linux/slab.h>
21 #include <linux/workqueue.h>
22
23 #include "power.h"
24
25 static DEFINE_MUTEX(wakelocks_lock);
26
27 struct wakelock {
28 char *name;
29 struct rb_node node;
30 struct wakeup_source *ws;
31 #ifdef CONFIG_PM_WAKELOCKS_GC
32 struct list_head lru;
33 #endif
34 };
35
36 static struct rb_root wakelocks_tree = RB_ROOT;
37
38 ssize_t pm_show_wakelocks(char *buf, bool show_active)
39 {
40 struct rb_node *node;
41 struct wakelock *wl;
42 int len = 0;
43
44 mutex_lock(&wakelocks_lock);
45
46 for (node = rb_first(&wakelocks_tree); node; node = rb_next(node)) {
47 wl = rb_entry(node, struct wakelock, node);
48 if (wl->ws->active == show_active)
49 len += sysfs_emit_at(buf, len, "%s ", wl->name);
50 }
51
52 len += sysfs_emit_at(buf, len, "\n");
53
54 mutex_unlock(&wakelocks_lock);
55 return len;
56 }
57
58 #if CONFIG_PM_WAKELOCKS_LIMIT > 0
59 static unsigned int number_of_wakelocks;
60
61 static inline bool wakelocks_limit_exceeded(void)
62 {
63 return number_of_wakelocks > CONFIG_PM_WAKELOCKS_LIMIT;
64 }
65
66 static inline void increment_wakelocks_number(void)
67 {
68 number_of_wakelocks++;
69 }
70
71 static inline void decrement_wakelocks_number(void)
72 {
73 number_of_wakelocks--;
74 }
75 #else /* CONFIG_PM_WAKELOCKS_LIMIT = 0 */
76 static inline bool wakelocks_limit_exceeded(void) { return false; }
77 static inline void increment_wakelocks_number(void) {}
78 static inline void decrement_wakelocks_number(void) {}
79 #endif /* CONFIG_PM_WAKELOCKS_LIMIT */
80
81 #ifdef CONFIG_PM_WAKELOCKS_GC
82 #define WL_GC_COUNT_MAX 100
83 #define WL_GC_TIME_SEC 300
84
85 static void __wakelocks_gc(struct work_struct *work);
86 static LIST_HEAD(wakelocks_lru_list);
87 static DECLARE_WORK(wakelock_work, __wakelocks_gc);
88 static unsigned int wakelocks_gc_count;
89
90 static inline void wakelocks_lru_add(struct wakelock *wl)
91 {
92 list_add(&wl->lru, &wakelocks_lru_list);
93 }
94
95 static inline void wakelocks_lru_most_recent(struct wakelock *wl)
96 {
97 list_move(&wl->lru, &wakelocks_lru_list);
98 }
99
100 static void __wakelocks_gc(struct work_struct *work)
101 {
102 struct wakelock *wl, *aux;
103 ktime_t now;
104
105 mutex_lock(&wakelocks_lock);
106
107 now = ktime_get();
108 list_for_each_entry_safe_reverse(wl, aux, &wakelocks_lru_list, lru) {
109 u64 idle_time_ns;
110 bool active;
111
112 spin_lock_irq(&wl->ws->lock);
113 idle_time_ns = ktime_to_ns(ktime_sub(now, wl->ws->last_time));
114 active = wl->ws->active;
115 spin_unlock_irq(&wl->ws->lock);
116
117 if (idle_time_ns < ((u64)WL_GC_TIME_SEC * NSEC_PER_SEC))
118 break;
119
120 if (!active) {
121 wakeup_source_unregister(wl->ws);
122 rb_erase(&wl->node, &wakelocks_tree);
123 list_del(&wl->lru);
124 kfree(wl->name);
125 kfree(wl);
126 decrement_wakelocks_number();
127 }
128 }
129 wakelocks_gc_count = 0;
130
131 mutex_unlock(&wakelocks_lock);
132 }
133
134 static void wakelocks_gc(void)
135 {
136 if (++wakelocks_gc_count <= WL_GC_COUNT_MAX)
137 return;
138
139 schedule_work(&wakelock_work);
140 }
141 #else /* !CONFIG_PM_WAKELOCKS_GC */
142 static inline void wakelocks_lru_add(struct wakelock *wl) {}
143 static inline void wakelocks_lru_most_recent(struct wakelock *wl) {}
144 static inline void wakelocks_gc(void) {}
145 #endif /* !CONFIG_PM_WAKELOCKS_GC */
146
147 static struct wakelock *wakelock_lookup_add(const char *name, size_t len,
148 bool add_if_not_found)
149 {
150 struct rb_node **node = &wakelocks_tree.rb_node;
151 struct rb_node *parent = *node;
152 struct wakelock *wl;
153
154 while (*node) {
155 int diff;
156
157 parent = *node;
158 wl = rb_entry(*node, struct wakelock, node);
159 diff = strncmp(name, wl->name, len);
160 if (diff == 0) {
161 if (wl->name[len])
162 diff = -1;
163 else
164 return wl;
165 }
166 if (diff < 0)
167 node = &(*node)->rb_left;
168 else
169 node = &(*node)->rb_right;
170 }
171 if (!add_if_not_found)
172 return ERR_PTR(-EINVAL);
173
174 if (wakelocks_limit_exceeded())
175 return ERR_PTR(-ENOSPC);
176
177 /* Not found, we have to add a new one. */
178 wl = kzalloc(sizeof(*wl), GFP_KERNEL);
179 if (!wl)
180 return ERR_PTR(-ENOMEM);
181
182 wl->name = kstrndup(name, len, GFP_KERNEL);
183 if (!wl->name) {
184 kfree(wl);
185 return ERR_PTR(-ENOMEM);
186 }
187
188 wl->ws = wakeup_source_register(NULL, wl->name);
189 if (!wl->ws) {
190 kfree(wl->name);
191 kfree(wl);
192 return ERR_PTR(-ENOMEM);
193 }
194 wl->ws->last_time = ktime_get();
195
196 rb_link_node(&wl->node, parent, node);
197 rb_insert_color(&wl->node, &wakelocks_tree);
198 wakelocks_lru_add(wl);
199 increment_wakelocks_number();
200 return wl;
201 }
202
203 int pm_wake_lock(const char *buf)
204 {
205 const char *str = buf;
206 struct wakelock *wl;
207 u64 timeout_ns = 0;
208 size_t len;
209 int ret = 0;
210
211 if (!capable(CAP_BLOCK_SUSPEND))
212 return -EPERM;
213
214 while (*str && !isspace(*str))
215 str++;
216
217 len = str - buf;
218 if (!len)
219 return -EINVAL;
220
221 if (*str && *str != '\n') {
222 /* Find out if there's a valid timeout string appended. */
223 ret = kstrtou64(skip_spaces(str), 10, &timeout_ns);
224 if (ret)
225 return -EINVAL;
226 }
227
228 mutex_lock(&wakelocks_lock);
229
230 wl = wakelock_lookup_add(buf, len, true);
231 if (IS_ERR(wl)) {
232 ret = PTR_ERR(wl);
233 goto out;
234 }
235 if (timeout_ns) {
236 u64 timeout_ms = timeout_ns + NSEC_PER_MSEC - 1;
237
238 do_div(timeout_ms, NSEC_PER_MSEC);
239 __pm_wakeup_event(wl->ws, timeout_ms);
240 } else {
241 __pm_stay_awake(wl->ws);
242 }
243
244 wakelocks_lru_most_recent(wl);
245
246 out:
247 mutex_unlock(&wakelocks_lock);
248 return ret;
249 }
250
251 int pm_wake_unlock(const char *buf)
252 {
253 struct wakelock *wl;
254 size_t len;
255 int ret = 0;
256
257 if (!capable(CAP_BLOCK_SUSPEND))
258 return -EPERM;
259
260 len = strlen(buf);
261 if (!len)
262 return -EINVAL;
263
264 if (buf[len-1] == '\n')
265 len--;
266
267 if (!len)
268 return -EINVAL;
269
270 mutex_lock(&wakelocks_lock);
271
272 wl = wakelock_lookup_add(buf, len, false);
273 if (IS_ERR(wl)) {
274 ret = PTR_ERR(wl);
275 goto out;
276 }
277 __pm_relax(wl->ws);
278
279 wakelocks_lru_most_recent(wl);
280 wakelocks_gc();
281
282 out:
283 mutex_unlock(&wakelocks_lock);
284 return ret;
285 }
286
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