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
  20 static DEFINE_MUTEX(wakelocks_lock);
  21
  22 struct 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
  31 static struct rb_root wakelocks_tree = RB_ROOT;
  32
  33 ssize_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
  57 static unsigned int number_of_wakelocks;
  58
  59 static inline bool wakelocks_limit_exceeded(void)
  60 {
  61         return number_of_wakelocks > CONFIG_PM_WAKELOCKS_LIMIT;
  62 }
  63
  64 static inline void increment_wakelocks_number(void)
  65 {
  66         number_of_wakelocks++;
  67 }
  68
  69 static inline void decrement_wakelocks_number(void)
  70 {
  71         number_of_wakelocks--;
  72 }
  73 #else /* CONFIG_PM_WAKELOCKS_LIMIT = 0 */
  74 static inline bool wakelocks_limit_exceeded(void) { return false; }
  75 static inline void increment_wakelocks_number(void) {}
  76 static 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
  83 static LIST_HEAD(wakelocks_lru_list);
  84 static unsigned int wakelocks_gc_count;
  85
  86 static inline void wakelocks_lru_add(struct wakelock *wl)
  87 {
  88         list_add(&wl->lru, &wakelocks_lru_list);
  89 }
  90
  91 static inline void wakelocks_lru_most_recent(struct wakelock *wl)
  92 {
  93         list_move(&wl->lru, &wakelocks_lru_list);
  94 }
  95
  96 static 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 */
 129 static inline void wakelocks_lru_add(struct wakelock *wl) {}
 130 static inline void wakelocks_lru_most_recent(struct wakelock *wl) {}
 131 static inline void wakelocks_gc(void) {}
 132 #endif /* !CONFIG_PM_WAKELOCKS_GC */
 133
 134 static 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
 183 int 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
 228 int 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 }