Re: [PATCH v2]: In kernel hibernation, suspend to both

[Rafael J. Wysocki]

On Tuesday, May 15, 2012, Bojan Smojver wrote:
> Hi Rafael,
> 
> Here is a new version of the patch, this time with comments by Srivatsa
> and Alan taken on board and applied to the patch (thank you guys!). I
> have tested this on my ThinkPad T510 and it worked.
> 
> ------------------------------
> Enable suspend to both for in-kernel hibernation.
> 
> It is often useful to suspend to memory after hibernation image has been
> written to disk. If the battery runs out or power is otherwise lost, the
> computer will resume from the hibernated image. If not, it will resume
> from memory and hibernation image will be discarded.
> 
> Signed-off-by: Bojan Smojver <bojan@xxxxxxxxxxxxx>
> ---
>  Documentation/power/swsusp.txt |    5 +++++
>  kernel/power/hibernate.c       |   43 ++++++++++++++++++++++++++++++++++++++++
>  kernel/power/power.h           |    3 +++
>  kernel/power/swap.c            |   28 ++++++++++++++++++++++++++
>  4 files changed, 79 insertions(+)
> 
> diff --git a/Documentation/power/swsusp.txt b/Documentation/power/swsusp.txt
> index ac190cf..92341b8 100644
> --- a/Documentation/power/swsusp.txt
> +++ b/Documentation/power/swsusp.txt
> @@ -33,6 +33,11 @@ echo shutdown > /sys/power/disk; echo disk > /sys/power/state
>  
>  echo platform > /sys/power/disk; echo disk > /sys/power/state
>  
> +. If you would like to write hibernation image to swap and then suspend
> +to RAM (provided your platform supports it), you can try
> +
> +echo suspend > /sys/power/disk; echo disk > /sys/power/state
> +
>  . If you have SATA disks, you'll need recent kernels with SATA suspend
>  support. For suspend and resume to work, make sure your disk drivers
>  are built into kernel -- not modules. [There's way to make
> diff --git a/kernel/power/hibernate.c b/kernel/power/hibernate.c
> index e09dfbf..a479fbd 100644
> --- a/kernel/power/hibernate.c
> +++ b/kernel/power/hibernate.c
> @@ -5,6 +5,7 @@
>   * Copyright (c) 2003 Open Source Development Lab
>   * Copyright (c) 2004 Pavel Machek <pavel@xxxxxx>
>   * Copyright (c) 2009 Rafael J. Wysocki, Novell Inc.
> + * Copyright (C) 2012 Bojan Smojver <bojan@xxxxxxxxxxxxx>
>   *
>   * This file is released under the GPLv2.
>   */
> @@ -44,6 +45,9 @@ enum {
>  	HIBERNATION_PLATFORM,
>  	HIBERNATION_SHUTDOWN,
>  	HIBERNATION_REBOOT,
> +#ifdef CONFIG_SUSPEND
> +	HIBERNATION_SUSPEND,
> +#endif
>  	/* keep last */
>  	__HIBERNATION_AFTER_LAST
>  };
> @@ -572,6 +576,10 @@ int hibernation_platform_enter(void)
>   */
>  static void power_down(void)
>  {
> +#ifdef CONFIG_SUSPEND
> +	int error;
> +#endif
> +
>  	switch (hibernation_mode) {
>  	case HIBERNATION_REBOOT:
>  		kernel_restart(NULL);
> @@ -581,6 +589,32 @@ static void power_down(void)
>  	case HIBERNATION_SHUTDOWN:
>  		kernel_power_off();
>  		break;
> +#ifdef CONFIG_SUSPEND
> +	case HIBERNATION_SUSPEND:
> +		error = pm_notifier_call_chain(PM_SUSPEND_PREPARE);

I wouldn't do that, really.  Some notifiers may assume user space to
be available and in that case that might just block.

> +		if (!error) {
> +			pr_debug("PM: Entering mem sleep.\n");
> +			error = suspend_devices_and_enter(PM_SUSPEND_MEM);
> +		}
> +		pm_notifier_call_chain(PM_POST_SUSPEND);
> +
> +		if (error) {
> +			pr_debug("PM: Mem sleep failed. Powering down.\n");
> +			if (hibernation_ops)
> +				hibernation_mode = HIBERNATION_PLATFORM;
> +			else
> +				hibernation_mode = HIBERNATION_SHUTDOWN;
> +			power_down();
> +		}
> +		/*
> +		 * Restore swap signature.
> +		 */
> +		error = swsusp_unmark();
> +		if (error)
> +			printk(KERN_ERR "PM: Swap will be unusable! "
> +			                "Try swapon -a.\n");
> +		return;
> +#endif
>  	}
>  	kernel_halt();
>  	/*
> @@ -814,6 +848,9 @@ static const char * const hibernation_modes[] = {
>  	[HIBERNATION_PLATFORM]	= "platform",
>  	[HIBERNATION_SHUTDOWN]	= "shutdown",
>  	[HIBERNATION_REBOOT]	= "reboot",
> +#ifdef CONFIG_SUSPEND
> +	[HIBERNATION_SUSPEND]	= "suspend",
> +#endif
>  };
>  
>  /*
> @@ -854,6 +891,9 @@ static ssize_t disk_show(struct kobject *kobj, struct kobj_attribute *attr,
>  		switch (i) {
>  		case HIBERNATION_SHUTDOWN:
>  		case HIBERNATION_REBOOT:
> +#ifdef CONFIG_SUSPEND
> +		case HIBERNATION_SUSPEND:
> +#endif
>  			break;
>  		case HIBERNATION_PLATFORM:
>  			if (hibernation_ops)
> @@ -894,6 +934,9 @@ static ssize_t disk_store(struct kobject *kobj, struct kobj_attribute *attr,
>  		switch (mode) {
>  		case HIBERNATION_SHUTDOWN:
>  		case HIBERNATION_REBOOT:
> +#ifdef CONFIG_SUSPEND
> +		case HIBERNATION_SUSPEND:
> +#endif
>  			hibernation_mode = mode;
>  			break;
>  		case HIBERNATION_PLATFORM:
> diff --git a/kernel/power/power.h b/kernel/power/power.h
> index 98f3622..07b4a68 100644
> --- a/kernel/power/power.h
> +++ b/kernel/power/power.h
> @@ -156,6 +156,9 @@ extern void swsusp_free(void);
>  extern int swsusp_read(unsigned int *flags_p);
>  extern int swsusp_write(unsigned int flags);
>  extern void swsusp_close(fmode_t);
> +#ifdef CONFIG_SUSPEND
> +extern int swsusp_unmark(void);
> +#endif
>  
>  /* kernel/power/block_io.c */
>  extern struct block_device *hib_resume_bdev;
> diff --git a/kernel/power/swap.c b/kernel/power/swap.c
> index eef311a..1027da8 100644
> --- a/kernel/power/swap.c
> +++ b/kernel/power/swap.c
> @@ -1456,6 +1456,34 @@ void swsusp_close(fmode_t mode)
>  	blkdev_put(hib_resume_bdev, mode);
>  }
>  
> +/**
> + *      swsusp_unmark - Unmark swsusp signature in the resume device
> + */
> +
> +#ifdef CONFIG_SUSPEND
> +int swsusp_unmark(void)
> +{
> +	int error;
> +
> +	hib_bio_read_page(swsusp_resume_block, swsusp_header, NULL);
> +	if (!memcmp(HIBERNATE_SIG,swsusp_header->sig, 10)) {
> +		memcpy(swsusp_header->sig,swsusp_header->orig_sig, 10);
> +		error = hib_bio_write_page(swsusp_resume_block,
> +					swsusp_header, NULL);
> +	} else {
> +		printk(KERN_ERR "PM: Cannot find swsusp signature!\n");
> +		error = -ENODEV;
> +	}
> +
> +	/*
> +	 * We just returned from suspend, we don't need the image any more.
> +	 */
> +	free_all_swap_pages(root_swap);
> +
> +	return error;
> +}
> +#endif
> +
>  static int swsusp_header_init(void)
>  {
>  	swsusp_header = (struct swsusp_header*) __get_free_page(GFP_KERNEL);
> ------------------------------

Thanks,
Rafael
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