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Date: Tue, 15 May 2012 19:45:12 +0200
From: "Rafael J. Wysocki" <rjw@...k.pl>
To: Bojan Smojver <bojan@...ursive.com>
Cc: Linux PM list <linux-pm@...r.kernel.org>,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2]: In kernel hibernation, suspend to both
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@...ursive.com>
> ---
> 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@....cz>
> * Copyright (c) 2009 Rafael J. Wysocki, Novell Inc.
> + * Copyright (C) 2012 Bojan Smojver <bojan@...ursive.com>
> *
> * 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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