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
  21static DEFINE_MUTEX(wakelocks_lock);
  22
  23struct 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
  32static struct rb_root wakelocks_tree = RB_ROOT;
  33
  34ssize_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
  58static unsigned int number_of_wakelocks;
  59
  60static inline bool wakelocks_limit_exceeded(void)
  61{
  62        return number_of_wakelocks > CONFIG_PM_WAKELOCKS_LIMIT;
  63}
  64
  65static inline void increment_wakelocks_number(void)
  66{
  67        number_of_wakelocks++;
  68}
  69
  70static inline void decrement_wakelocks_number(void)
  71{
  72        number_of_wakelocks--;
  73}
  74#else /* CONFIG_PM_WAKELOCKS_LIMIT = 0 */
  75static inline bool wakelocks_limit_exceeded(void) { return false; }
  76static inline void increment_wakelocks_number(void) {}
  77static 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
  84static LIST_HEAD(wakelocks_lru_list);
  85static unsigned int wakelocks_gc_count;
  86
  87static inline void wakelocks_lru_add(struct wakelock *wl)
  88{
  89        list_add(&wl->lru, &wakelocks_lru_list);
  90}
  91
  92static inline void wakelocks_lru_most_recent(struct wakelock *wl)
  93{
  94        list_move(&wl->lru, &wakelocks_lru_list);
  95}
  96
  97static 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 */
 130static inline void wakelocks_lru_add(struct wakelock *wl) {}
 131static inline void wakelocks_lru_most_recent(struct wakelock *wl) {}
 132static inline void wakelocks_gc(void) {}
 133#endif /* !CONFIG_PM_WAKELOCKS_GC */
 134
 135static 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
 184int 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
 232int 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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