PM / Sleep: Add user space interface for manipulating wakeup sources, v3

Android allows user space to manipulate wakelocks using two
sysfs file located in /sys/power/, wake_lock and wake_unlock.
Writing a wakelock name and optionally a timeout to the wake_lock
file causes the wakelock whose name was written to be acquired (it
is created before is necessary), optionally with the given timeout.
Writing the name of a wakelock to wake_unlock causes that wakelock
to be released.

Implement an analogous interface for user space using wakeup sources.
Add the /sys/power/wake_lock and /sys/power/wake_unlock files
allowing user space to create, activate and deactivate wakeup
sources, such that writing a name and optionally a timeout to
wake_lock causes the wakeup source of that name to be activated,
optionally with the given timeout.  If that wakeup source doesn't
exist, it will be created and then activated.  Writing a name to
wake_unlock causes the wakeup source of that name, if there is one,
to be deactivated.  Wakeup sources created with the help of
wake_lock that haven't been used for more than 5 minutes are garbage
collected and destroyed.  Moreover, there can be only WL_NUMBER_LIMIT
wakeup sources created with the help of wake_lock present at a time.

The data type used to track wakeup sources created by user space is
called "struct wakelock" to indicate the origins of this feature.

This version of the patch includes an rbtree manipulation fix from John Stultz.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: NeilBrown <neilb@suse.de>
This commit is contained in:
Rafael J. Wysocki 2012-04-29 22:53:42 +02:00
parent 55850945e8
commit b86ff9820f
7 changed files with 317 additions and 0 deletions

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@ -189,3 +189,45 @@ Description:
Reading from this file causes the last string successfully
written to it to be returned.
What: /sys/power/wake_lock
Date: February 2012
Contact: Rafael J. Wysocki <rjw@sisk.pl>
Description:
The /sys/power/wake_lock file allows user space to create
wakeup source objects and activate them on demand (if one of
those wakeup sources is active, reads from the
/sys/power/wakeup_count file block or return false). When a
string without white space is written to /sys/power/wake_lock,
it will be assumed to represent a wakeup source name. If there
is a wakeup source object with that name, it will be activated
(unless active already). Otherwise, a new wakeup source object
will be registered, assigned the given name and activated.
If a string written to /sys/power/wake_lock contains white
space, the part of the string preceding the white space will be
regarded as a wakeup source name and handled as descrived above.
The other part of the string will be regarded as a timeout (in
nanoseconds) such that the wakeup source will be automatically
deactivated after it has expired. The timeout, if present, is
set regardless of the current state of the wakeup source object
in question.
Reads from this file return a string consisting of the names of
wakeup sources created with the help of it that are active at
the moment, separated with spaces.
What: /sys/power/wake_unlock
Date: February 2012
Contact: Rafael J. Wysocki <rjw@sisk.pl>
Description:
The /sys/power/wake_unlock file allows user space to deactivate
wakeup sources created with the help of /sys/power/wake_lock.
When a string is written to /sys/power/wake_unlock, it will be
assumed to represent the name of a wakeup source to deactivate.
If a wakeup source object of that name exists and is active at
the moment, it will be deactivated.
Reads from this file return a string consisting of the names of
wakeup sources created with the help of /sys/power/wake_lock
that are inactive at the moment, separated with spaces.

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@ -133,6 +133,7 @@ void wakeup_source_add(struct wakeup_source *ws)
spin_lock_init(&ws->lock);
setup_timer(&ws->timer, pm_wakeup_timer_fn, (unsigned long)ws);
ws->active = false;
ws->last_time = ktime_get();
spin_lock_irq(&events_lock);
list_add_rcu(&ws->entry, &wakeup_sources);

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@ -111,6 +111,14 @@ config PM_AUTOSLEEP
Allow the kernel to trigger a system transition into a global sleep
state automatically whenever there are no active wakeup sources.
config PM_WAKELOCKS
bool "User space wakeup sources interface"
depends on PM_SLEEP
default n
---help---
Allow user space to create, activate and deactivate wakeup source
objects with the help of a sysfs-based interface.
config PM_RUNTIME
bool "Run-time PM core functionality"
depends on !IA64_HP_SIM

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@ -10,5 +10,6 @@ obj-$(CONFIG_PM_TEST_SUSPEND) += suspend_test.o
obj-$(CONFIG_HIBERNATION) += hibernate.o snapshot.o swap.o user.o \
block_io.o
obj-$(CONFIG_PM_AUTOSLEEP) += autosleep.o
obj-$(CONFIG_PM_WAKELOCKS) += wakelock.o
obj-$(CONFIG_MAGIC_SYSRQ) += poweroff.o

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@ -431,6 +431,43 @@ static ssize_t autosleep_store(struct kobject *kobj,
power_attr(autosleep);
#endif /* CONFIG_PM_AUTOSLEEP */
#ifdef CONFIG_PM_WAKELOCKS
static ssize_t wake_lock_show(struct kobject *kobj,
struct kobj_attribute *attr,
char *buf)
{
return pm_show_wakelocks(buf, true);
}
static ssize_t wake_lock_store(struct kobject *kobj,
struct kobj_attribute *attr,
const char *buf, size_t n)
{
int error = pm_wake_lock(buf);
return error ? error : n;
}
power_attr(wake_lock);
static ssize_t wake_unlock_show(struct kobject *kobj,
struct kobj_attribute *attr,
char *buf)
{
return pm_show_wakelocks(buf, false);
}
static ssize_t wake_unlock_store(struct kobject *kobj,
struct kobj_attribute *attr,
const char *buf, size_t n)
{
int error = pm_wake_unlock(buf);
return error ? error : n;
}
power_attr(wake_unlock);
#endif /* CONFIG_PM_WAKELOCKS */
#endif /* CONFIG_PM_SLEEP */
#ifdef CONFIG_PM_TRACE
@ -487,6 +524,10 @@ static struct attribute * g[] = {
#ifdef CONFIG_PM_AUTOSLEEP
&autosleep_attr.attr,
#endif
#ifdef CONFIG_PM_WAKELOCKS
&wake_lock_attr.attr,
&wake_unlock_attr.attr,
#endif
#ifdef CONFIG_PM_DEBUG
&pm_test_attr.attr,
#endif

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@ -282,3 +282,12 @@ static inline void pm_autosleep_unlock(void) {}
static inline suspend_state_t pm_autosleep_state(void) { return PM_SUSPEND_ON; }
#endif /* !CONFIG_PM_AUTOSLEEP */
#ifdef CONFIG_PM_WAKELOCKS
/* kernel/power/wakelock.c */
extern ssize_t pm_show_wakelocks(char *buf, bool show_active);
extern int pm_wake_lock(const char *buf);
extern int pm_wake_unlock(const char *buf);
#endif /* !CONFIG_PM_WAKELOCKS */

215
kernel/power/wakelock.c Normal file
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@ -0,0 +1,215 @@
/*
* 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/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>
#define WL_NUMBER_LIMIT 100
#define WL_GC_COUNT_MAX 100
#define WL_GC_TIME_SEC 300
static DEFINE_MUTEX(wakelocks_lock);
struct wakelock {
char *name;
struct rb_node node;
struct wakeup_source ws;
struct list_head lru;
};
static struct rb_root wakelocks_tree = RB_ROOT;
static LIST_HEAD(wakelocks_lru_list);
static unsigned int number_of_wakelocks;
static unsigned int wakelocks_gc_count;
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);
}
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 (number_of_wakelocks > WL_NUMBER_LIMIT)
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;
wakeup_source_add(&wl->ws);
rb_link_node(&wl->node, parent, node);
rb_insert_color(&wl->node, &wakelocks_tree);
list_add(&wl->lru, &wakelocks_lru_list);
number_of_wakelocks++;
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;
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);
}
list_move(&wl->lru, &wakelocks_lru_list);
out:
mutex_unlock(&wakelocks_lock);
return ret;
}
static void wakelocks_gc(void)
{
struct wakelock *wl, *aux;
ktime_t 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);
number_of_wakelocks--;
}
}
wakelocks_gc_count = 0;
}
int pm_wake_unlock(const char *buf)
{
struct wakelock *wl;
size_t len;
int ret = 0;
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);
list_move(&wl->lru, &wakelocks_lru_list);
if (++wakelocks_gc_count > WL_GC_COUNT_MAX)
wakelocks_gc();
out:
mutex_unlock(&wakelocks_lock);
return ret;
}