Message-Id: <200803132154.59910.rjw@sisk.pl>
Date:	Thu, 13 Mar 2008 21:54:58 +0100
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Pavel Machek <pavel@....cz>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...e.hu>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ralf Baechle <ralf@...ux-mips.org>,
	David Howells <dhowells@...hat.com>
Subject: Re: pm_register() and pm_send_all()

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@...e.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);
> -
--
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