linux/kernel/power/wakelock.c
Doug Berger 2ef7c01c0c PM / wakeup: Only update last time for active wakeup sources
When wakelock support was added, the wakeup_source_add() function
was updated to set the last_time value of the wakeup source. This
has the unintended side effect of producing confusing output from
pm_print_active_wakeup_sources() when a wakeup source is added
prior to a sleep that is blocked by a different wakeup source.

The function pm_print_active_wakeup_sources() will search for the
most recently active wakeup source when no active source is found.
If a wakeup source is added after a different wakeup source blocks
the system from going to sleep it may have a later last_time value
than the blocking source and be output as the last active wakeup
source even if it has never actually been active.

It looks to me like the change to wakeup_source_add() was made to
prevent the wakelock garbage collection from accidentally dropping
a wakelock during the narrow window between adding the wakelock to
the wakelock list in wakelock_lookup_add() and the activation of
the wakeup source in pm_wake_lock().

This commit changes the behavior so that only the last_time of the
wakeup source used by a wakelock is initialized prior to adding it
to the wakeup source list. This preserves the meaning of the
last_time value as the last time the wakeup source was active and
allows a wakeup source that has never been active to have a
last_time value of 0.

Fixes: b86ff9820f (PM / Sleep: Add user space interface for manipulating wakeup sources, v3)
Signed-off-by: Doug Berger <opendmb@gmail.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2018-05-10 11:39:19 +02:00

283 lines
5.8 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* kernel/power/wakelock.c
*
* User space wakeup sources support.
*
* Copyright (C) 2012 Rafael J. Wysocki <rjw@sisk.pl>
*
* This code is based on the analogous interface allowing user space to
* manipulate wakelocks on Android.
*/
#include <linux/capability.h>
#include <linux/ctype.h>
#include <linux/device.h>
#include <linux/err.h>
#include <linux/hrtimer.h>
#include <linux/list.h>
#include <linux/rbtree.h>
#include <linux/slab.h>
#include <linux/workqueue.h>
#include "power.h"
static DEFINE_MUTEX(wakelocks_lock);
struct wakelock {
char *name;
struct rb_node node;
struct wakeup_source ws;
#ifdef CONFIG_PM_WAKELOCKS_GC
struct list_head lru;
#endif
};
static struct rb_root wakelocks_tree = RB_ROOT;
ssize_t pm_show_wakelocks(char *buf, bool show_active)
{
struct rb_node *node;
struct wakelock *wl;
char *str = buf;
char *end = buf + PAGE_SIZE;
mutex_lock(&wakelocks_lock);
for (node = rb_first(&wakelocks_tree); node; node = rb_next(node)) {
wl = rb_entry(node, struct wakelock, node);
if (wl->ws.active == show_active)
str += scnprintf(str, end - str, "%s ", wl->name);
}
if (str > buf)
str--;
str += scnprintf(str, end - str, "\n");
mutex_unlock(&wakelocks_lock);
return (str - buf);
}
#if CONFIG_PM_WAKELOCKS_LIMIT > 0
static unsigned int number_of_wakelocks;
static inline bool wakelocks_limit_exceeded(void)
{
return number_of_wakelocks > CONFIG_PM_WAKELOCKS_LIMIT;
}
static inline void increment_wakelocks_number(void)
{
number_of_wakelocks++;
}
static inline void decrement_wakelocks_number(void)
{
number_of_wakelocks--;
}
#else /* CONFIG_PM_WAKELOCKS_LIMIT = 0 */
static inline bool wakelocks_limit_exceeded(void) { return false; }
static inline void increment_wakelocks_number(void) {}
static inline void decrement_wakelocks_number(void) {}
#endif /* CONFIG_PM_WAKELOCKS_LIMIT */
#ifdef CONFIG_PM_WAKELOCKS_GC
#define WL_GC_COUNT_MAX 100
#define WL_GC_TIME_SEC 300
static void __wakelocks_gc(struct work_struct *work);
static LIST_HEAD(wakelocks_lru_list);
static DECLARE_WORK(wakelock_work, __wakelocks_gc);
static unsigned int wakelocks_gc_count;
static inline void wakelocks_lru_add(struct wakelock *wl)
{
list_add(&wl->lru, &wakelocks_lru_list);
}
static inline void wakelocks_lru_most_recent(struct wakelock *wl)
{
list_move(&wl->lru, &wakelocks_lru_list);
}
static void __wakelocks_gc(struct work_struct *work)
{
struct wakelock *wl, *aux;
ktime_t now;
mutex_lock(&wakelocks_lock);
now = ktime_get();
list_for_each_entry_safe_reverse(wl, aux, &wakelocks_lru_list, lru) {
u64 idle_time_ns;
bool active;
spin_lock_irq(&wl->ws.lock);
idle_time_ns = ktime_to_ns(ktime_sub(now, wl->ws.last_time));
active = wl->ws.active;
spin_unlock_irq(&wl->ws.lock);
if (idle_time_ns < ((u64)WL_GC_TIME_SEC * NSEC_PER_SEC))
break;
if (!active) {
wakeup_source_remove(&wl->ws);
rb_erase(&wl->node, &wakelocks_tree);
list_del(&wl->lru);
kfree(wl->name);
kfree(wl);
decrement_wakelocks_number();
}
}
wakelocks_gc_count = 0;
mutex_unlock(&wakelocks_lock);
}
static void wakelocks_gc(void)
{
if (++wakelocks_gc_count <= WL_GC_COUNT_MAX)
return;
schedule_work(&wakelock_work);
}
#else /* !CONFIG_PM_WAKELOCKS_GC */
static inline void wakelocks_lru_add(struct wakelock *wl) {}
static inline void wakelocks_lru_most_recent(struct wakelock *wl) {}
static inline void wakelocks_gc(void) {}
#endif /* !CONFIG_PM_WAKELOCKS_GC */
static struct wakelock *wakelock_lookup_add(const char *name, size_t len,
bool add_if_not_found)
{
struct rb_node **node = &wakelocks_tree.rb_node;
struct rb_node *parent = *node;
struct wakelock *wl;
while (*node) {
int diff;
parent = *node;
wl = rb_entry(*node, struct wakelock, node);
diff = strncmp(name, wl->name, len);
if (diff == 0) {
if (wl->name[len])
diff = -1;
else
return wl;
}
if (diff < 0)
node = &(*node)->rb_left;
else
node = &(*node)->rb_right;
}
if (!add_if_not_found)
return ERR_PTR(-EINVAL);
if (wakelocks_limit_exceeded())
return ERR_PTR(-ENOSPC);
/* Not found, we have to add a new one. */
wl = kzalloc(sizeof(*wl), GFP_KERNEL);
if (!wl)
return ERR_PTR(-ENOMEM);
wl->name = kstrndup(name, len, GFP_KERNEL);
if (!wl->name) {
kfree(wl);
return ERR_PTR(-ENOMEM);
}
wl->ws.name = wl->name;
wl->ws.last_time = ktime_get();
wakeup_source_add(&wl->ws);
rb_link_node(&wl->node, parent, node);
rb_insert_color(&wl->node, &wakelocks_tree);
wakelocks_lru_add(wl);
increment_wakelocks_number();
return wl;
}
int pm_wake_lock(const char *buf)
{
const char *str = buf;
struct wakelock *wl;
u64 timeout_ns = 0;
size_t len;
int ret = 0;
if (!capable(CAP_BLOCK_SUSPEND))
return -EPERM;
while (*str && !isspace(*str))
str++;
len = str - buf;
if (!len)
return -EINVAL;
if (*str && *str != '\n') {
/* Find out if there's a valid timeout string appended. */
ret = kstrtou64(skip_spaces(str), 10, &timeout_ns);
if (ret)
return -EINVAL;
}
mutex_lock(&wakelocks_lock);
wl = wakelock_lookup_add(buf, len, true);
if (IS_ERR(wl)) {
ret = PTR_ERR(wl);
goto out;
}
if (timeout_ns) {
u64 timeout_ms = timeout_ns + NSEC_PER_MSEC - 1;
do_div(timeout_ms, NSEC_PER_MSEC);
__pm_wakeup_event(&wl->ws, timeout_ms);
} else {
__pm_stay_awake(&wl->ws);
}
wakelocks_lru_most_recent(wl);
out:
mutex_unlock(&wakelocks_lock);
return ret;
}
int pm_wake_unlock(const char *buf)
{
struct wakelock *wl;
size_t len;
int ret = 0;
if (!capable(CAP_BLOCK_SUSPEND))
return -EPERM;
len = strlen(buf);
if (!len)
return -EINVAL;
if (buf[len-1] == '\n')
len--;
if (!len)
return -EINVAL;
mutex_lock(&wakelocks_lock);
wl = wakelock_lookup_add(buf, len, false);
if (IS_ERR(wl)) {
ret = PTR_ERR(wl);
goto out;
}
__pm_relax(&wl->ws);
wakelocks_lru_most_recent(wl);
wakelocks_gc();
out:
mutex_unlock(&wakelocks_lock);
return ret;
}