Root/kernel/power/wakelock.c

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

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