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