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Linux/kernel/power/wakelock.c

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

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