wakelock.c

  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
 25static DEFINE_MUTEX(wakelocks_lock);
 26
 27struct 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
 36static struct rb_root wakelocks_tree = RB_ROOT;
 37
 38ssize_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	if (len > 0)
 53		--len;
 54
 55	len += sysfs_emit_at(buf, len, "\n");
 56
 57	mutex_unlock(&wakelocks_lock);
 58	return len;
 59}
 60
 61#if CONFIG_PM_WAKELOCKS_LIMIT > 0
 62static unsigned int number_of_wakelocks;
 63
 64static inline bool wakelocks_limit_exceeded(void)
 65{
 66	return number_of_wakelocks > CONFIG_PM_WAKELOCKS_LIMIT;
 67}
 68
 69static inline void increment_wakelocks_number(void)
 70{
 71	number_of_wakelocks++;
 72}
 73
 74static inline void decrement_wakelocks_number(void)
 75{
 76	number_of_wakelocks--;
 77}
 78#else /* CONFIG_PM_WAKELOCKS_LIMIT = 0 */
 79static inline bool wakelocks_limit_exceeded(void) { return false; }
 80static inline void increment_wakelocks_number(void) {}
 81static inline void decrement_wakelocks_number(void) {}
 82#endif /* CONFIG_PM_WAKELOCKS_LIMIT */
 83
 84#ifdef CONFIG_PM_WAKELOCKS_GC
 85#define WL_GC_COUNT_MAX	100
 86#define WL_GC_TIME_SEC	300
 87
 88static void __wakelocks_gc(struct work_struct *work);
 89static LIST_HEAD(wakelocks_lru_list);
 90static DECLARE_WORK(wakelock_work, __wakelocks_gc);
 91static unsigned int wakelocks_gc_count;
 92
 93static inline void wakelocks_lru_add(struct wakelock *wl)
 94{
 95	list_add(&wl->lru, &wakelocks_lru_list);
 96}
 97
 98static inline void wakelocks_lru_most_recent(struct wakelock *wl)
 99{
100	list_move(&wl->lru, &wakelocks_lru_list);
101}
102
103static void __wakelocks_gc(struct work_struct *work)
104{
105	struct wakelock *wl, *aux;
106	ktime_t now;
107
108	mutex_lock(&wakelocks_lock);
109
110	now = ktime_get();
111	list_for_each_entry_safe_reverse(wl, aux, &wakelocks_lru_list, lru) {
112		u64 idle_time_ns;
113		bool active;
114
115		spin_lock_irq(&wl->ws->lock);
116		idle_time_ns = ktime_to_ns(ktime_sub(now, wl->ws->last_time));
117		active = wl->ws->active;
118		spin_unlock_irq(&wl->ws->lock);
119
120		if (idle_time_ns < ((u64)WL_GC_TIME_SEC * NSEC_PER_SEC))
121			break;
122
123		if (!active) {
124			wakeup_source_unregister(wl->ws);
125			rb_erase(&wl->node, &wakelocks_tree);
126			list_del(&wl->lru);
127			kfree(wl->name);
128			kfree(wl);
129			decrement_wakelocks_number();
130		}
131	}
132	wakelocks_gc_count = 0;
133
134	mutex_unlock(&wakelocks_lock);
135}
136
137static void wakelocks_gc(void)
138{
139	if (++wakelocks_gc_count <= WL_GC_COUNT_MAX)
140		return;
141
142	schedule_work(&wakelock_work);
143}
144#else /* !CONFIG_PM_WAKELOCKS_GC */
145static inline void wakelocks_lru_add(struct wakelock *wl) {}
146static inline void wakelocks_lru_most_recent(struct wakelock *wl) {}
147static inline void wakelocks_gc(void) {}
148#endif /* !CONFIG_PM_WAKELOCKS_GC */
149
150static struct wakelock *wakelock_lookup_add(const char *name, size_t len,
151					    bool add_if_not_found)
152{
153	struct rb_node **node = &wakelocks_tree.rb_node;
154	struct rb_node *parent = *node;
155	struct wakelock *wl;
156
157	while (*node) {
158		int diff;
159
160		parent = *node;
161		wl = rb_entry(*node, struct wakelock, node);
162		diff = strncmp(name, wl->name, len);
163		if (diff == 0) {
164			if (wl->name[len])
165				diff = -1;
166			else
167				return wl;
168		}
169		if (diff < 0)
170			node = &(*node)->rb_left;
171		else
172			node = &(*node)->rb_right;
173	}
174	if (!add_if_not_found)
175		return ERR_PTR(-EINVAL);
176
177	if (wakelocks_limit_exceeded())
178		return ERR_PTR(-ENOSPC);
179
180	/* Not found, we have to add a new one. */
181	wl = kzalloc(sizeof(*wl), GFP_KERNEL);
182	if (!wl)
183		return ERR_PTR(-ENOMEM);
184
185	wl->name = kstrndup(name, len, GFP_KERNEL);
186	if (!wl->name) {
187		kfree(wl);
188		return ERR_PTR(-ENOMEM);
189	}
190
191	wl->ws = wakeup_source_register(NULL, wl->name);
192	if (!wl->ws) {
193		kfree(wl->name);
194		kfree(wl);
195		return ERR_PTR(-ENOMEM);
196	}
197	wl->ws->last_time = ktime_get();
198
199	rb_link_node(&wl->node, parent, node);
200	rb_insert_color(&wl->node, &wakelocks_tree);
201	wakelocks_lru_add(wl);
202	increment_wakelocks_number();
203	return wl;
204}
205
206int pm_wake_lock(const char *buf)
207{
208	const char *str = buf;
209	struct wakelock *wl;
210	u64 timeout_ns = 0;
211	size_t len;
212	int ret = 0;
213
214	if (!capable(CAP_BLOCK_SUSPEND))
215		return -EPERM;
216
217	while (*str && !isspace(*str))
218		str++;
219
220	len = str - buf;
221	if (!len)
222		return -EINVAL;
223
224	if (*str && *str != '\n') {
225		/* Find out if there's a valid timeout string appended. */
226		ret = kstrtou64(skip_spaces(str), 10, &timeout_ns);
227		if (ret)
228			return -EINVAL;
229	}
230
231	mutex_lock(&wakelocks_lock);
232
233	wl = wakelock_lookup_add(buf, len, true);
234	if (IS_ERR(wl)) {
235		ret = PTR_ERR(wl);
236		goto out;
237	}
238	if (timeout_ns) {
239		u64 timeout_ms = timeout_ns + NSEC_PER_MSEC - 1;
240
241		do_div(timeout_ms, NSEC_PER_MSEC);
242		__pm_wakeup_event(wl->ws, timeout_ms);
243	} else {
244		__pm_stay_awake(wl->ws);
245	}
246
247	wakelocks_lru_most_recent(wl);
248
249 out:
250	mutex_unlock(&wakelocks_lock);
251	return ret;
252}
253
254int pm_wake_unlock(const char *buf)
255{
256	struct wakelock *wl;
257	size_t len;
258	int ret = 0;
259
260	if (!capable(CAP_BLOCK_SUSPEND))
261		return -EPERM;
262
263	len = strlen(buf);
264	if (!len)
265		return -EINVAL;
266
267	if (buf[len-1] == '\n')
268		len--;
269
270	if (!len)
271		return -EINVAL;
272
273	mutex_lock(&wakelocks_lock);
274
275	wl = wakelock_lookup_add(buf, len, false);
276	if (IS_ERR(wl)) {
277		ret = PTR_ERR(wl);
278		goto out;
279	}
280	__pm_relax(wl->ws);
281
282	wakelocks_lru_most_recent(wl);
283	wakelocks_gc();
284
285 out:
286	mutex_unlock(&wakelocks_lock);
287	return ret;
288}