linux/kernel/power/main.c
Rafael J. Wysocki e3c7db621b [PATCH] PM: Change code ordering in main.c
As indicated in a recent thread on Linux-PM, it's necessary to call
pm_ops->finish() before devce_resume(), but enable_nonboot_cpus() has to be
called before pm_ops->finish() (cf.
http://lists.osdl.org/pipermail/linux-pm/2006-November/004164.html).  For
consistency, it seems reasonable to call disable_nonboot_cpus() after
device_suspend().

This way the suspend code will remain symmetrical with respect to the resume
code and it may allow us to speed up things in the future by suspending and
resuming devices and/or saving the suspend image in many threads.

The following series of patches reorders the suspend and resume code so that
nonboot CPUs are disabled after devices have been suspended and enabled before
the devices are resumed.  It also causes pm_ops->finish() to be called after
enable_nonboot_cpus() wherever necessary.

This patch:

Change the ordering of code in kernel/power/main.c so that device_suspend()
is called before disable_nonboot_cpus() and pm_ops->finish() is called after
enable_nonboot_cpus() and before device_resume(), as indicated by recent
discussion on Linux-PM
(cf. http://lists.osdl.org/pipermail/linux-pm/2006-November/004164.html).

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Pavel Machek <pavel@ucw.cz>
Cc: Greg KH <greg@kroah.com>
Cc: Nigel Cunningham <nigel@suspend2.net>
Cc: Patrick Mochel <mochel@digitalimplant.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-02-11 10:51:19 -08:00

340 lines
6.9 KiB
C

/*
* kernel/power/main.c - PM subsystem core functionality.
*
* Copyright (c) 2003 Patrick Mochel
* Copyright (c) 2003 Open Source Development Lab
*
* This file is released under the GPLv2
*
*/
#include <linux/module.h>
#include <linux/suspend.h>
#include <linux/kobject.h>
#include <linux/string.h>
#include <linux/delay.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/pm.h>
#include <linux/console.h>
#include <linux/cpu.h>
#include <linux/resume-trace.h>
#include <linux/freezer.h>
#include <linux/vmstat.h>
#include "power.h"
/*This is just an arbitrary number */
#define FREE_PAGE_NUMBER (100)
DEFINE_MUTEX(pm_mutex);
struct pm_ops *pm_ops;
suspend_disk_method_t pm_disk_mode = PM_DISK_PLATFORM;
/**
* pm_set_ops - Set the global power method table.
* @ops: Pointer to ops structure.
*/
void pm_set_ops(struct pm_ops * ops)
{
mutex_lock(&pm_mutex);
pm_ops = ops;
mutex_unlock(&pm_mutex);
}
static inline void pm_finish(suspend_state_t state)
{
if (pm_ops->finish)
pm_ops->finish(state);
}
/**
* suspend_prepare - Do prep work before entering low-power state.
* @state: State we're entering.
*
* This is common code that is called for each state that we're
* entering. Allocate a console, stop all processes, then make sure
* the platform can enter the requested state.
*/
static int suspend_prepare(suspend_state_t state)
{
int error;
unsigned int free_pages;
if (!pm_ops || !pm_ops->enter)
return -EPERM;
pm_prepare_console();
if (freeze_processes()) {
error = -EAGAIN;
goto Thaw;
}
if ((free_pages = global_page_state(NR_FREE_PAGES))
< FREE_PAGE_NUMBER) {
pr_debug("PM: free some memory\n");
shrink_all_memory(FREE_PAGE_NUMBER - free_pages);
if (nr_free_pages() < FREE_PAGE_NUMBER) {
error = -ENOMEM;
printk(KERN_ERR "PM: No enough memory\n");
goto Thaw;
}
}
if (pm_ops->prepare) {
if ((error = pm_ops->prepare(state)))
goto Thaw;
}
suspend_console();
error = device_suspend(PMSG_SUSPEND);
if (error) {
printk(KERN_ERR "Some devices failed to suspend\n");
goto Resume_devices;
}
error = disable_nonboot_cpus();
if (!error)
return 0;
enable_nonboot_cpus();
Resume_devices:
pm_finish(state);
device_resume();
resume_console();
Thaw:
thaw_processes();
pm_restore_console();
return error;
}
int suspend_enter(suspend_state_t state)
{
int error = 0;
unsigned long flags;
local_irq_save(flags);
if ((error = device_power_down(PMSG_SUSPEND))) {
printk(KERN_ERR "Some devices failed to power down\n");
goto Done;
}
error = pm_ops->enter(state);
device_power_up();
Done:
local_irq_restore(flags);
return error;
}
/**
* suspend_finish - Do final work before exiting suspend sequence.
* @state: State we're coming out of.
*
* Call platform code to clean up, restart processes, and free the
* console that we've allocated. This is not called for suspend-to-disk.
*/
static void suspend_finish(suspend_state_t state)
{
enable_nonboot_cpus();
pm_finish(state);
device_resume();
resume_console();
thaw_processes();
pm_restore_console();
}
static const char * const pm_states[PM_SUSPEND_MAX] = {
[PM_SUSPEND_STANDBY] = "standby",
[PM_SUSPEND_MEM] = "mem",
#ifdef CONFIG_SOFTWARE_SUSPEND
[PM_SUSPEND_DISK] = "disk",
#endif
};
static inline int valid_state(suspend_state_t state)
{
/* Suspend-to-disk does not really need low-level support.
* It can work with reboot if needed. */
if (state == PM_SUSPEND_DISK)
return 1;
if (pm_ops && pm_ops->valid && !pm_ops->valid(state))
return 0;
return 1;
}
/**
* enter_state - Do common work of entering low-power state.
* @state: pm_state structure for state we're entering.
*
* Make sure we're the only ones trying to enter a sleep state. Fail
* if someone has beat us to it, since we don't want anything weird to
* happen when we wake up.
* Then, do the setup for suspend, enter the state, and cleaup (after
* we've woken up).
*/
static int enter_state(suspend_state_t state)
{
int error;
if (!valid_state(state))
return -ENODEV;
if (!mutex_trylock(&pm_mutex))
return -EBUSY;
if (state == PM_SUSPEND_DISK) {
error = pm_suspend_disk();
goto Unlock;
}
pr_debug("PM: Preparing system for %s sleep\n", pm_states[state]);
if ((error = suspend_prepare(state)))
goto Unlock;
pr_debug("PM: Entering %s sleep\n", pm_states[state]);
error = suspend_enter(state);
pr_debug("PM: Finishing wakeup.\n");
suspend_finish(state);
Unlock:
mutex_unlock(&pm_mutex);
return error;
}
/*
* This is main interface to the outside world. It needs to be
* called from process context.
*/
int software_suspend(void)
{
return enter_state(PM_SUSPEND_DISK);
}
/**
* pm_suspend - Externally visible function for suspending system.
* @state: Enumarted value of state to enter.
*
* Determine whether or not value is within range, get state
* structure, and enter (above).
*/
int pm_suspend(suspend_state_t state)
{
if (state > PM_SUSPEND_ON && state <= PM_SUSPEND_MAX)
return enter_state(state);
return -EINVAL;
}
EXPORT_SYMBOL(pm_suspend);
decl_subsys(power,NULL,NULL);
/**
* state - control system power state.
*
* show() returns what states are supported, which is hard-coded to
* 'standby' (Power-On Suspend), 'mem' (Suspend-to-RAM), and
* 'disk' (Suspend-to-Disk).
*
* store() accepts one of those strings, translates it into the
* proper enumerated value, and initiates a suspend transition.
*/
static ssize_t state_show(struct subsystem * subsys, char * buf)
{
int i;
char * s = buf;
for (i = 0; i < PM_SUSPEND_MAX; i++) {
if (pm_states[i] && valid_state(i))
s += sprintf(s,"%s ", pm_states[i]);
}
s += sprintf(s,"\n");
return (s - buf);
}
static ssize_t state_store(struct subsystem * subsys, const char * buf, size_t n)
{
suspend_state_t state = PM_SUSPEND_STANDBY;
const char * const *s;
char *p;
int error;
int len;
p = memchr(buf, '\n', n);
len = p ? p - buf : n;
for (s = &pm_states[state]; state < PM_SUSPEND_MAX; s++, state++) {
if (*s && !strncmp(buf, *s, len))
break;
}
if (state < PM_SUSPEND_MAX && *s)
error = enter_state(state);
else
error = -EINVAL;
return error ? error : n;
}
power_attr(state);
#ifdef CONFIG_PM_TRACE
int pm_trace_enabled;
static ssize_t pm_trace_show(struct subsystem * subsys, char * buf)
{
return sprintf(buf, "%d\n", pm_trace_enabled);
}
static ssize_t
pm_trace_store(struct subsystem * subsys, const char * buf, size_t n)
{
int val;
if (sscanf(buf, "%d", &val) == 1) {
pm_trace_enabled = !!val;
return n;
}
return -EINVAL;
}
power_attr(pm_trace);
static struct attribute * g[] = {
&state_attr.attr,
&pm_trace_attr.attr,
NULL,
};
#else
static struct attribute * g[] = {
&state_attr.attr,
NULL,
};
#endif /* CONFIG_PM_TRACE */
static struct attribute_group attr_group = {
.attrs = g,
};
static int __init pm_init(void)
{
int error = subsystem_register(&power_subsys);
if (!error)
error = sysfs_create_group(&power_subsys.kset.kobj,&attr_group);
return error;
}
core_initcall(pm_init);