Re: pm_register() and pm_send_all()

Rafael J. Wysocki
2008-03-13T20:56:20Z

On Thursday, 13 of March 2008, Pavel Machek wrote:
> On Wed 2008-03-12 15:00:42, Andrew Morton wrote:
> >
> > This:
> >
> > kernel/power/pm.c:203: warning: 'pm_register' is deprecated (declared at kernel/power/pm.c:62)
> > kernel/power/pm.c:203: warning: 'pm_register' is deprecated (declared at kernel/power/pm.c:62)
> > kernel/power/pm.c:204: warning: 'pm_send_all' is deprecated (declared at kernel/power/pm.c:178)
> > kernel/power/pm.c:204: warning: 'pm_send_all' is deprecated (declared at kernel/power/pm.c:178)
> >
> > is getting a bit boring. These were marked deprecated at least three years
> > ago.
> >
> >
> > pm_register() no longer has any callers and afacit can be removed
> > immediately.
> >
> > pm_send_all() has just a handful of callers:
> >
> > arch/x86/kernel/apm_32.c
> > arch/mips/au1000/common/power.c
> > arch/frv/kernel/pm.c
>
> AFAICT pm_send_all is a nop when noone uses pm_register...

Apparently on 2.6.24 it's not used anywehere, at least according to LXR.

> Hmm.. can we just force CONFIG_PM_LEGACY=n, and see what happens?

Do you want me to push this patch and the following one from Ralf to Len?

> Or maybe this is better idea? It may break build somewhere, but it
> should be easy to fix... (it builds here, i386 and x86-64).
>
> Signed-off-by: Pavel Machek <pavel@suse.cz>
>
> diff --git a/arch/frv/kernel/pm.c b/arch/frv/kernel/pm.c
> index c57ce3f..73f3aee 100644
> --- a/arch/frv/kernel/pm.c
> +++ b/arch/frv/kernel/pm.c
> @@ -163,14 +163,11 @@ static int sysctl_pm_do_suspend(ctl_tabl
> if ((mode != 1) && (mode != 5))
> return -EINVAL;
>
> - retval = pm_send_all(PM_SUSPEND, (void *)3);
> -
> if (retval == 0) {
> if (mode == 5)
> retval = pm_do_bus_sleep();
> else
> retval = pm_do_suspend();
> - pm_send_all(PM_RESUME, (void *)0);
> }
>
> return retval;
> @@ -183,9 +180,6 @@ static int try_set_cmode(int new_cmode)
> if (!(clock_cmodes_permitted & (1<<new_cmode)))
> return -EINVAL;
>
> - /* tell all the drivers we're suspending */
> - pm_send_all(PM_SUSPEND, (void *)3);
> -
> /* now change cmode */
> local_irq_disable();
> frv_dma_pause_all();
> @@ -201,8 +195,6 @@ #endif
> frv_dma_resume_all();
> local_irq_enable();
>
> - /* tell all the drivers we're resuming */
> - pm_send_all(PM_RESUME, (void *)0);
> return 0;
> }
>
> diff --git a/arch/mips/au1000/common/power.c b/arch/mips/au1000/common/power.c
> index 54047d6..a9f7f63 100644
> --- a/arch/mips/au1000/common/power.c
> +++ b/arch/mips/au1000/common/power.c
> @@ -258,7 +258,6 @@ #endif
> static int pm_do_sleep(ctl_table * ctl, int write, struct file *file,
> void __user *buffer, size_t * len, loff_t *ppos)
> {
> - int retval = 0;
> #ifdef SLEEP_TEST_TIMEOUT
> #define TMPBUFLEN2 16
> char buf[TMPBUFLEN2], *p;
> @@ -278,33 +277,21 @@ #ifdef SLEEP_TEST_TIMEOUT
> p = buf;
> sleep_ticks = simple_strtoul(p, &p, 0);
> #endif
> - retval = pm_send_all(PM_SUSPEND, (void *) 2);
> -
> - if (retval)
> - return retval;
>
> au_sleep();
> - retval = pm_send_all(PM_RESUME, (void *) 0);
> }
> - return retval;
> + return 0;
> }
>
> static int pm_do_suspend(ctl_table * ctl, int write, struct file *file,
> void __user *buffer, size_t * len, loff_t *ppos)
> {
> - int retval = 0;
> -
> if (!write) {
> *len = 0;
> } else {
> - retval = pm_send_all(PM_SUSPEND, (void *) 2);
> - if (retval)
> - return retval;
> suspend_mode = 1;
> -
> - retval = pm_send_all(PM_RESUME, (void *) 0);
> }
> - return retval;
> + return 0;
> }
>
>
> diff --git a/arch/x86/kernel/apm_32.c b/arch/x86/kernel/apm_32.c
> index d4438ef..d7e92bf 100644
> --- a/arch/x86/kernel/apm_32.c
> +++ b/arch/x86/kernel/apm_32.c
> @@ -1189,19 +1189,6 @@ static int suspend(int vetoable)
> int err;
> struct apm_user *as;
>
> - if (pm_send_all(PM_SUSPEND, (void *)3)) {
> - /* Vetoed */
> - if (vetoable) {
> - if (apm_info.connection_version > 0x100)
> - set_system_power_state(APM_STATE_REJECT);
> - err = -EBUSY;
> - ignore_sys_suspend = 0;
> - printk(KERN_WARNING "apm: suspend was vetoed.\n");
> - goto out;
> - }
> - printk(KERN_CRIT "apm: suspend was vetoed, but suspending anyway.\n");
> - }
> -
> device_suspend(PMSG_SUSPEND);
> local_irq_disable();
> device_power_down(PMSG_SUSPEND);
> @@ -1224,7 +1211,6 @@ static int suspend(int vetoable)
> device_power_up();
> local_irq_enable();
> device_resume();
> - pm_send_all(PM_RESUME, (void *)0);
> queue_event(APM_NORMAL_RESUME, NULL);
> out:
> spin_lock(&user_list_lock);
> @@ -1337,7 +1323,6 @@ #endif
> if ((event != APM_NORMAL_RESUME)
> || (ignore_normal_resume == 0)) {
> device_resume();
> - pm_send_all(PM_RESUME, (void *)0);
> queue_event(event, NULL);
> }
> ignore_normal_resume = 0;
> diff --git a/kernel/power/Kconfig b/kernel/power/Kconfig
> index e2d7b39..d6d8f8b 100644
> --- a/kernel/power/Kconfig
> +++ b/kernel/power/Kconfig
> @@ -19,16 +19,6 @@ config PM
> will issue the hlt instruction if nothing is to be done, thereby
> sending the processor to sleep and saving power.
>
> -config PM_LEGACY
> - bool "Legacy Power Management API (DEPRECATED)"
> - depends on PM
> - default n
> - ---help---
> - Support for pm_register() and friends. This old API is obsoleted
> - by the driver model.
> -
> - If unsure, say N.
> -
> config PM_DEBUG
> bool "Power Management Debug Support"
> depends on PM
> diff --git a/kernel/power/Makefile b/kernel/power/Makefile
> index e5693d6..523abb9 100644
> --- a/kernel/power/Makefile
> +++ b/kernel/power/Makefile
> @@ -4,7 +4,6 @@ EXTRA_CFLAGS += -DDEBUG
> endif
>
> obj-y := main.o
> -obj-$(CONFIG_PM_LEGACY) += pm.o
> obj-$(CONFIG_PM_SLEEP) += process.o console.o sleepy.o
> obj-$(CONFIG_HIBERNATION) += swsusp.o disk.o snapshot.o swap.o user.o
>
> diff --git a/kernel/power/pm.c b/kernel/power/pm.c
> deleted file mode 100644
> index 60c73fa..0000000
> --- a/kernel/power/pm.c
> +++ /dev/null
> @@ -1,205 +0,0 @@
> -/*
> - * pm.c - Power management interface
> - *
> - * Copyright (C) 2000 Andrew Henroid
> - *
> - * This program is free software; you can redistribute it and/or modify
> - * it under the terms of the GNU General Public License as published by
> - * the Free Software Foundation; either version 2 of the License, or
> - * (at your option) any later version.
> - *
> - * This program is distributed in the hope that it will be useful,
> - * but WITHOUT ANY WARRANTY; without even the implied warranty of
> - * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> - * GNU General Public License for more details.
> - *
> - * You should have received a copy of the GNU General Public License
> - * along with this program; if not, write to the Free Software
> - * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
> - */
> -#include <linux/init.h>
> -#include <linux/module.h>
> -#include <linux/spinlock.h>
> -#include <linux/mm.h>
> -#include <linux/slab.h>
> -#include <linux/pm.h>
> -#include <linux/pm_legacy.h>
> -#include <linux/interrupt.h>
> -#include <linux/mutex.h>
> -
> -/*
> - * Locking notes:
> - * pm_devs_lock can be a semaphore providing pm ops are not called
> - * from an interrupt handler (already a bad idea so no change here). Each
> - * change must be protected so that an unlink of an entry doesn't clash
> - * with a pm send - which is permitted to sleep in the current architecture
> - *
> - * Module unloads clashing with pm events now work out safely, the module
> - * unload path will block until the event has been sent. It may well block
> - * until a resume but that will be fine.
> - */
> -
> -static DEFINE_MUTEX(pm_devs_lock);
> -static LIST_HEAD(pm_devs);
> -
> -/**
> - * pm_register - register a device with power management
> - * @type: device type
> - * @id: device ID
> - * @callback: callback function
> - *
> - * Add a device to the list of devices that wish to be notified about
> - * power management events. A &pm_dev structure is returned on success,
> - * on failure the return is %NULL.
> - *
> - * The callback function will be called in process context and
> - * it may sleep.
> - */
> -
> -struct pm_dev *pm_register(pm_dev_t type,
> - unsigned long id,
> - pm_callback callback)
> -{
> - struct pm_dev *dev = kzalloc(sizeof(struct pm_dev), GFP_KERNEL);
> - if (dev) {
> - dev->type = type;
> - dev->id = id;
> - dev->callback = callback;
> -
> - mutex_lock(&pm_devs_lock);
> - list_add(&dev->entry, &pm_devs);
> - mutex_unlock(&pm_devs_lock);
> - }
> - return dev;
> -}
> -
> -/**
> - * pm_send - send request to a single device
> - * @dev: device to send to
> - * @rqst: power management request
> - * @data: data for the callback
> - *
> - * Issue a power management request to a given device. The
> - * %PM_SUSPEND and %PM_RESUME events are handled specially. The
> - * data field must hold the intended next state. No call is made
> - * if the state matches.
> - *
> - * BUGS: what stops two power management requests occurring in parallel
> - * and conflicting.
> - *
> - * WARNING: Calling pm_send directly is not generally recommended, in
> - * particular there is no locking against the pm_dev going away. The
> - * caller must maintain all needed locking or have 'inside knowledge'
> - * on the safety. Also remember that this function is not locked against
> - * pm_unregister. This means that you must handle SMP races on callback
> - * execution and unload yourself.
> - */
> -
> -static int pm_send(struct pm_dev *dev, pm_request_t rqst, void *data)
> -{
> - int status = 0;
> - unsigned long prev_state, next_state;
> -
> - if (in_interrupt())
> - BUG();
> -
> - switch (rqst) {
> - case PM_SUSPEND:
> - case PM_RESUME:
> - prev_state = dev->state;
> - next_state = (unsigned long) data;
> - if (prev_state != next_state) {
> - if (dev->callback)
> - status = (*dev->callback)(dev, rqst, data);
> - if (!status) {
> - dev->state = next_state;
> - dev->prev_state = prev_state;
> - }
> - }
> - else {
> - dev->prev_state = prev_state;
> - }
> - break;
> - default:
> - if (dev->callback)
> - status = (*dev->callback)(dev, rqst, data);
> - break;
> - }
> - return status;
> -}
> -
> -/*
> - * Undo incomplete request
> - */
> -static void pm_undo_all(struct pm_dev *last)
> -{
> - struct list_head *entry = last->entry.prev;
> - while (entry != &pm_devs) {
> - struct pm_dev *dev = list_entry(entry, struct pm_dev, entry);
> - if (dev->state != dev->prev_state) {
> - /* previous state was zero (running) resume or
> - * previous state was non-zero (suspended) suspend
> - */
> - pm_request_t undo = (dev->prev_state
> - ? PM_SUSPEND:PM_RESUME);
> - pm_send(dev, undo, (void*) dev->prev_state);
> - }
> - entry = entry->prev;
> - }
> -}
> -
> -/**
> - * pm_send_all - send request to all managed devices
> - * @rqst: power management request
> - * @data: data for the callback
> - *
> - * Issue a power management request to a all devices. The
> - * %PM_SUSPEND events are handled specially. Any device is
> - * permitted to fail a suspend by returning a non zero (error)
> - * value from its callback function. If any device vetoes a
> - * suspend request then all other devices that have suspended
> - * during the processing of this request are restored to their
> - * previous state.
> - *
> - * WARNING: This function takes the pm_devs_lock. The lock is not dropped until
> - * the callbacks have completed. This prevents races against pm locking
> - * functions, races against module unload pm_unregister code. It does
> - * mean however that you must not issue pm_ functions within the callback
> - * or you will deadlock and users will hate you.
> - *
> - * Zero is returned on success. If a suspend fails then the status
> - * from the device that vetoes the suspend is returned.
> - *
> - * BUGS: what stops two power management requests occurring in parallel
> - * and conflicting.
> - */
> -
> -int pm_send_all(pm_request_t rqst, void *data)
> -{
> - struct list_head *entry;
> -
> - mutex_lock(&pm_devs_lock);
> - entry = pm_devs.next;
> - while (entry != &pm_devs) {
> - struct pm_dev *dev = list_entry(entry, struct pm_dev, entry);
> - if (dev->callback) {
> - int status = pm_send(dev, rqst, data);
> - if (status) {
> - /* return devices to previous state on
> - * failed suspend request
> - */
> - if (rqst == PM_SUSPEND)
> - pm_undo_all(dev);
> - mutex_unlock(&pm_devs_lock);
> - return status;
> - }
> - }
> - entry = entry->next;
> - }
> - mutex_unlock(&pm_devs_lock);
> - return 0;
> -}
> -
> -EXPORT_SYMBOL(pm_register);
> -EXPORT_SYMBOL(pm_send_all);
> -