kernel/power/wakelock.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * kernel/power/wakelock.c
   4  *
   5  * User space wakeup sources support.
   6  *
   7  * Copyright (C) 2012 Rafael J. Wysocki <rjw@sisk.pl>
   8  *
   9  * This code is based on the analogous interface allowing user space to
  10  * manipulate wakelocks on Android.
  11  */
  12
  13 #include <linux/capability.h>
  14 #include <linux/ctype.h>
  15 #include <linux/device.h>
  16 #include <linux/err.h>
  17 #include <linux/hrtimer.h>
  18 #include <linux/list.h>
  19 #include <linux/rbtree.h>
  20 #include <linux/slab.h>
  21 #include <linux/workqueue.h>
  22
  23 #include "power.h"
  24
  25 static DEFINE_MUTEX(wakelocks_lock);
  26
  27 struct wakelock {
  28         char                    *name;
  29         struct rb_node          node;
  30         struct wakeup_source    ws;
  31 #ifdef CONFIG_PM_WAKELOCKS_GC
  32         struct list_head        lru;
  33 #endif
  34 };
  35
  36 static struct rb_root wakelocks_tree = RB_ROOT;
  37
  38 ssize_t pm_show_wakelocks(char *buf, bool show_active)
  39 {
  40         struct rb_node *node;
  41         struct wakelock *wl;
  42         char *str = buf;
  43         char *end = buf + PAGE_SIZE;
  44
  45         mutex_lock(&wakelocks_lock);
  46
  47         for (node = rb_first(&wakelocks_tree); node; node = rb_next(node)) {
  48                 wl = rb_entry(node, struct wakelock, node);
  49                 if (wl->ws.active == show_active)
  50                         str += scnprintf(str, end - str, "%s ", wl->name);
  51         }
  52         if (str > buf)
  53                 str--;
  54
  55         str += scnprintf(str, end - str, "\n");
  56
  57         mutex_unlock(&wakelocks_lock);
  58         return (str - buf);
  59 }
  60
  61 #if CONFIG_PM_WAKELOCKS_LIMIT > 0
  62 static unsigned int number_of_wakelocks;
  63
  64 static inline bool wakelocks_limit_exceeded(void)
  65 {
  66         return number_of_wakelocks > CONFIG_PM_WAKELOCKS_LIMIT;
  67 }
  68
  69 static inline void increment_wakelocks_number(void)
  70 {
  71         number_of_wakelocks++;
  72 }
  73
  74 static inline void decrement_wakelocks_number(void)
  75 {
  76         number_of_wakelocks--;
  77 }
  78 #else /* CONFIG_PM_WAKELOCKS_LIMIT = 0 */
  79 static inline bool wakelocks_limit_exceeded(void) { return false; }
  80 static inline void increment_wakelocks_number(void) {}
  81 static inline void decrement_wakelocks_number(void) {}
  82 #endif /* CONFIG_PM_WAKELOCKS_LIMIT */
  83
  84 #ifdef CONFIG_PM_WAKELOCKS_GC
  85 #define WL_GC_COUNT_MAX 100
  86 #define WL_GC_TIME_SEC  300
  87
  88 static void __wakelocks_gc(struct work_struct *work);
  89 static LIST_HEAD(wakelocks_lru_list);
  90 static DECLARE_WORK(wakelock_work, __wakelocks_gc);
  91 static unsigned int wakelocks_gc_count;
  92
  93 static inline void wakelocks_lru_add(struct wakelock *wl)
  94 {
  95         list_add(&wl->lru, &wakelocks_lru_list);
  96 }
  97
  98 static inline void wakelocks_lru_most_recent(struct wakelock *wl)
  99 {
 100         list_move(&wl->lru, &wakelocks_lru_list);
 101 }
 102
 103 static void __wakelocks_gc(struct work_struct *work)
 104 {
 105         struct wakelock *wl, *aux;
 106         ktime_t now;
 107
 108         mutex_lock(&wakelocks_lock);
 109
 110         now = ktime_get();
 111         list_for_each_entry_safe_reverse(wl, aux, &wakelocks_lru_list, lru) {
 112                 u64 idle_time_ns;
 113                 bool active;
 114
 115                 spin_lock_irq(&wl->ws.lock);
 116                 idle_time_ns = ktime_to_ns(ktime_sub(now, wl->ws.last_time));
 117                 active = wl->ws.active;
 118                 spin_unlock_irq(&wl->ws.lock);
 119
 120                 if (idle_time_ns < ((u64)WL_GC_TIME_SEC * NSEC_PER_SEC))
 121                         break;
 122
 123                 if (!active) {
 124                         wakeup_source_remove(&wl->ws);
 125                         rb_erase(&wl->node, &wakelocks_tree);
 126                         list_del(&wl->lru);
 127                         kfree(wl->name);
 128                         kfree(wl);
 129                         decrement_wakelocks_number();
 130                 }
 131         }
 132         wakelocks_gc_count = 0;
 133
 134         mutex_unlock(&wakelocks_lock);
 135 }
 136
 137 static void wakelocks_gc(void)
 138 {
 139         if (++wakelocks_gc_count <= WL_GC_COUNT_MAX)
 140                 return;
 141
 142         schedule_work(&wakelock_work);
 143 }
 144 #else /* !CONFIG_PM_WAKELOCKS_GC */
 145 static inline void wakelocks_lru_add(struct wakelock *wl) {}
 146 static inline void wakelocks_lru_most_recent(struct wakelock *wl) {}
 147 static inline void wakelocks_gc(void) {}
 148 #endif /* !CONFIG_PM_WAKELOCKS_GC */
 149
 150 static struct wakelock *wakelock_lookup_add(const char *name, size_t len,
 151                                             bool add_if_not_found)
 152 {
 153         struct rb_node **node = &wakelocks_tree.rb_node;
 154         struct rb_node *parent = *node;
 155         struct wakelock *wl;
 156
 157         while (*node) {
 158                 int diff;
 159
 160                 parent = *node;
 161                 wl = rb_entry(*node, struct wakelock, node);
 162                 diff = strncmp(name, wl->name, len);
 163                 if (diff == 0) {
 164                         if (wl->name[len])
 165                                 diff = -1;
 166                         else
 167                                 return wl;
 168                 }
 169                 if (diff < 0)
 170                         node = &(*node)->rb_left;
 171                 else
 172                         node = &(*node)->rb_right;
 173         }
 174         if (!add_if_not_found)
 175                 return ERR_PTR(-EINVAL);
 176
 177         if (wakelocks_limit_exceeded())
 178                 return ERR_PTR(-ENOSPC);
 179
 180         /* Not found, we have to add a new one. */
 181         wl = kzalloc(sizeof(*wl), GFP_KERNEL);
 182         if (!wl)
 183                 return ERR_PTR(-ENOMEM);
 184
 185         wl->name = kstrndup(name, len, GFP_KERNEL);
 186         if (!wl->name) {
 187                 kfree(wl);
 188                 return ERR_PTR(-ENOMEM);
 189         }
 190         wl->ws.name = wl->name;
 191         wl->ws.last_time = ktime_get();
 192         wakeup_source_add(&wl->ws);
 193         rb_link_node(&wl->node, parent, node);
 194         rb_insert_color(&wl->node, &wakelocks_tree);
 195         wakelocks_lru_add(wl);
 196         increment_wakelocks_number();
 197         return wl;
 198 }
 199
 200 int pm_wake_lock(const char *buf)
 201 {
 202         const char *str = buf;
 203         struct wakelock *wl;
 204         u64 timeout_ns = 0;
 205         size_t len;
 206         int ret = 0;
 207
 208         if (!capable(CAP_BLOCK_SUSPEND))
 209                 return -EPERM;
 210
 211         while (*str && !isspace(*str))
 212                 str++;
 213
 214         len = str - buf;
 215         if (!len)
 216                 return -EINVAL;
 217
 218         if (*str && *str != '\n') {
 219                 /* Find out if there's a valid timeout string appended. */
 220                 ret = kstrtou64(skip_spaces(str), 10, &timeout_ns);
 221                 if (ret)
 222                         return -EINVAL;
 223         }
 224
 225         mutex_lock(&wakelocks_lock);
 226
 227         wl = wakelock_lookup_add(buf, len, true);
 228         if (IS_ERR(wl)) {
 229                 ret = PTR_ERR(wl);
 230                 goto out;
 231         }
 232         if (timeout_ns) {
 233                 u64 timeout_ms = timeout_ns + NSEC_PER_MSEC - 1;
 234
 235                 do_div(timeout_ms, NSEC_PER_MSEC);
 236                 __pm_wakeup_event(&wl->ws, timeout_ms);
 237         } else {
 238                 __pm_stay_awake(&wl->ws);
 239         }
 240
 241         wakelocks_lru_most_recent(wl);
 242
 243  out:
 244         mutex_unlock(&wakelocks_lock);
 245         return ret;
 246 }
 247
 248 int pm_wake_unlock(const char *buf)
 249 {
 250         struct wakelock *wl;
 251         size_t len;
 252         int ret = 0;
 253
 254         if (!capable(CAP_BLOCK_SUSPEND))
 255                 return -EPERM;
 256
 257         len = strlen(buf);
 258         if (!len)
 259                 return -EINVAL;
 260
 261         if (buf[len-1] == '\n')
 262                 len--;
 263
 264         if (!len)
 265                 return -EINVAL;
 266
 267         mutex_lock(&wakelocks_lock);
 268
 269         wl = wakelock_lookup_add(buf, len, false);
 270         if (IS_ERR(wl)) {
 271                 ret = PTR_ERR(wl);
 272                 goto out;
 273         }
 274         __pm_relax(&wl->ws);
 275
 276         wakelocks_lru_most_recent(wl);
 277         wakelocks_gc();
 278
 279  out:
 280         mutex_unlock(&wakelocks_lock);
 281         return ret;
 282 }