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
  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 }