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 #include "power.h"
  22
  23 static DEFINE_MUTEX(wakelocks_lock);
  24
  25 struct wakelock {
  26         char                    *name;
  27         struct rb_node          node;
  28         struct wakeup_source    ws;
  29 #ifdef CONFIG_PM_WAKELOCKS_GC
  30         struct list_head        lru;
  31 #endif
  32 };
  33
  34 static struct rb_root wakelocks_tree = RB_ROOT;
  35
  36 ssize_t pm_show_wakelocks(char *buf, bool show_active)
  37 {
  38         struct rb_node *node;
  39         struct wakelock *wl;
  40         char *str = buf;
  41         char *end = buf + PAGE_SIZE;
  42
  43         mutex_lock(&wakelocks_lock);
  44
  45         for (node = rb_first(&wakelocks_tree); node; node = rb_next(node)) {
  46                 wl = rb_entry(node, struct wakelock, node);
  47                 if (wl->ws.active == show_active)
  48                         str += scnprintf(str, end - str, "%s ", wl->name);
  49         }
  50         if (str > buf)
  51                 str--;
  52
  53         str += scnprintf(str, end - str, "\n");
  54
  55         mutex_unlock(&wakelocks_lock);
  56         return (str - buf);
  57 }
  58
  59 #if CONFIG_PM_WAKELOCKS_LIMIT > 0
  60 static unsigned int number_of_wakelocks;
  61
  62 static inline bool wakelocks_limit_exceeded(void)
  63 {
  64         return number_of_wakelocks > CONFIG_PM_WAKELOCKS_LIMIT;
  65 }
  66
  67 static inline void increment_wakelocks_number(void)
  68 {
  69         number_of_wakelocks++;
  70 }
  71
  72 static inline void decrement_wakelocks_number(void)
  73 {
  74         number_of_wakelocks--;
  75 }
  76 #else /* CONFIG_PM_WAKELOCKS_LIMIT = 0 */
  77 static inline bool wakelocks_limit_exceeded(void) { return false; }
  78 static inline void increment_wakelocks_number(void) {}
  79 static inline void decrement_wakelocks_number(void) {}
  80 #endif /* CONFIG_PM_WAKELOCKS_LIMIT */
  81
  82 #ifdef CONFIG_PM_WAKELOCKS_GC
  83 #define WL_GC_COUNT_MAX 100
  84 #define WL_GC_TIME_SEC  300
  85
  86 static LIST_HEAD(wakelocks_lru_list);
  87 static unsigned int wakelocks_gc_count;
  88
  89 static inline void wakelocks_lru_add(struct wakelock *wl)
  90 {
  91         list_add(&wl->lru, &wakelocks_lru_list);
  92 }
  93
  94 static inline void wakelocks_lru_most_recent(struct wakelock *wl)
  95 {
  96         list_move(&wl->lru, &wakelocks_lru_list);
  97 }
  98
  99 static void wakelocks_gc(void)
 100 {
 101         struct wakelock *wl, *aux;
 102         ktime_t now;
 103
 104         if (++wakelocks_gc_count <= WL_GC_COUNT_MAX)
 105                 return;
 106
 107         now = ktime_get();
 108         list_for_each_entry_safe_reverse(wl, aux, &wakelocks_lru_list, lru) {
 109                 u64 idle_time_ns;
 110                 bool active;
 111
 112                 spin_lock_irq(&wl->ws.lock);
 113                 idle_time_ns = ktime_to_ns(ktime_sub(now, wl->ws.last_time));
 114                 active = wl->ws.active;
 115                 spin_unlock_irq(&wl->ws.lock);
 116
 117                 if (idle_time_ns < ((u64)WL_GC_TIME_SEC * NSEC_PER_SEC))
 118                         break;
 119
 120                 if (!active) {
 121                         wakeup_source_remove(&wl->ws);
 122                         rb_erase(&wl->node, &wakelocks_tree);
 123                         list_del(&wl->lru);
 124                         kfree(wl->name);
 125                         kfree(wl);
 126                         decrement_wakelocks_number();
 127                 }
 128         }
 129         wakelocks_gc_count = 0;
 130 }
 131 #else /* !CONFIG_PM_WAKELOCKS_GC */
 132 static inline void wakelocks_lru_add(struct wakelock *wl) {}
 133 static inline void wakelocks_lru_most_recent(struct wakelock *wl) {}
 134 static inline void wakelocks_gc(void) {}
 135 #endif /* !CONFIG_PM_WAKELOCKS_GC */
 136
 137 static struct wakelock *wakelock_lookup_add(const char *name, size_t len,
 138                                             bool add_if_not_found)
 139 {
 140         struct rb_node **node = &wakelocks_tree.rb_node;
 141         struct rb_node *parent = *node;
 142         struct wakelock *wl;
 143
 144         while (*node) {
 145                 int diff;
 146
 147                 parent = *node;
 148                 wl = rb_entry(*node, struct wakelock, node);
 149                 diff = strncmp(name, wl->name, len);
 150                 if (diff == 0) {
 151                         if (wl->name[len])
 152                                 diff = -1;
 153                         else
 154                                 return wl;
 155                 }
 156                 if (diff < 0)
 157                         node = &(*node)->rb_left;
 158                 else
 159                         node = &(*node)->rb_right;
 160         }
 161         if (!add_if_not_found)
 162                 return ERR_PTR(-EINVAL);
 163
 164         if (wakelocks_limit_exceeded())
 165                 return ERR_PTR(-ENOSPC);
 166
 167         /* Not found, we have to add a new one. */
 168         wl = kzalloc(sizeof(*wl), GFP_KERNEL);
 169         if (!wl)
 170                 return ERR_PTR(-ENOMEM);
 171
 172         wl->name = kstrndup(name, len, GFP_KERNEL);
 173         if (!wl->name) {
 174                 kfree(wl);
 175                 return ERR_PTR(-ENOMEM);
 176         }
 177         wl->ws.name = wl->name;
 178         wakeup_source_add(&wl->ws);
 179         rb_link_node(&wl->node, parent, node);
 180         rb_insert_color(&wl->node, &wakelocks_tree);
 181         wakelocks_lru_add(wl);
 182         increment_wakelocks_number();
 183         return wl;
 184 }
 185
 186 int pm_wake_lock(const char *buf)
 187 {
 188         const char *str = buf;
 189         struct wakelock *wl;
 190         u64 timeout_ns = 0;
 191         size_t len;
 192         int ret = 0;
 193
 194         if (!capable(CAP_BLOCK_SUSPEND))
 195                 return -EPERM;
 196
 197         while (*str && !isspace(*str))
 198                 str++;
 199
 200         len = str - buf;
 201         if (!len)
 202                 return -EINVAL;
 203
 204         if (*str && *str != '\n') {
 205                 /* Find out if there's a valid timeout string appended. */
 206                 ret = kstrtou64(skip_spaces(str), 10, &timeout_ns);
 207                 if (ret)
 208                         return -EINVAL;
 209         }
 210
 211         mutex_lock(&wakelocks_lock);
 212
 213         wl = wakelock_lookup_add(buf, len, true);
 214         if (IS_ERR(wl)) {
 215                 ret = PTR_ERR(wl);
 216                 goto out;
 217         }
 218         if (timeout_ns) {
 219                 u64 timeout_ms = timeout_ns + NSEC_PER_MSEC - 1;
 220
 221                 do_div(timeout_ms, NSEC_PER_MSEC);
 222                 __pm_wakeup_event(&wl->ws, timeout_ms);
 223         } else {
 224                 __pm_stay_awake(&wl->ws);
 225         }
 226
 227         wakelocks_lru_most_recent(wl);
 228
 229  out:
 230         mutex_unlock(&wakelocks_lock);
 231         return ret;
 232 }
 233
 234 int pm_wake_unlock(const char *buf)
 235 {
 236         struct wakelock *wl;
 237         size_t len;
 238         int ret = 0;
 239
 240         if (!capable(CAP_BLOCK_SUSPEND))
 241                 return -EPERM;
 242
 243         len = strlen(buf);
 244         if (!len)
 245                 return -EINVAL;
 246
 247         if (buf[len-1] == '\n')
 248                 len--;
 249
 250         if (!len)
 251                 return -EINVAL;
 252
 253         mutex_lock(&wakelocks_lock);
 254
 255         wl = wakelock_lookup_add(buf, len, false);
 256         if (IS_ERR(wl)) {
 257                 ret = PTR_ERR(wl);
 258                 goto out;
 259         }
 260         __pm_relax(&wl->ws);
 261
 262         wakelocks_lru_most_recent(wl);
 263         wakelocks_gc();
 264
 265  out:
 266         mutex_unlock(&wakelocks_lock);
 267         return ret;
 268 }