Re: [Xen-devel] [PATCH] xen: use freeze/restore/thaw PM events for suspend/resume/chkpt

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Wed, 2011-02-16 at 06:51 +0000, Shriram Rajagopalan wrote:
> Use PM_FREEZE, PM_THAW and PM_RESTORE power events for
> suspend/resume/checkpoint functionality, instead of PM_SUSPEND
> and PM_RESUME. Use of these pm events fixes the Xen Guest hangup
> when taking checkpoints. When a suspend event is cancelled
> (while taking checkpoints once/continuously), we use PM_THAW
> instead of PM_RESUME. PM_RESTORE is used when suspend is not
> cancelled. See Documentation/power/devices.txt and linux/pm.h
> for more info about freeze, thaw and restore. The sequence of
> pm events in a suspend-resume scenario is shown below.
> 
>         dpm_suspend_start(PMSG_FREEZE);
> 
>                 dpm_suspend_noirq(PMSG_FREEZE);
> 
>                        sysdev_suspend(PMSG_FREEZE);
>                        cancelled = suspend_hypercall()
>                        sysdev_resume();
> 
>                dpm_resume_noirq(cancelled ? PMSG_THAW : PMSG_RESTORE);
> 
>        dpm_resume_end(cancelled ? PMSG_THAW : PMSG_RESTORE);

With this patch I get

[   18.902808] PM: Device pcspkr failed to freeze: error -22
[   18.902835] xen suspend: dpm_suspend_start -22

apparently due to a lack of CONFIG_HIBERNATE which is a prerequisite for
using the freeze methods (see pm_ops function).

As I mentioned earlier I think some of the CONFIG_PM_SLEEP tests in
drivers/xen/manage.c need to be adjusted for the new suspend scheme (and
I suspect they are a little wrong for the old one too).

Since CONFIG_HIBERNATE is a "suspend to disk" option I think this needs
running past the core pm guys to determine the correct approach, it
might be to make PMSG_FREEZE support enabled by some some less specific
configuration option.

Enabling CONFIG_HIBERNATE does seem to be sufficient to make this work
though.

Ian.


> 
> Signed-off-by: Shriram Rajagopalan <rshriram@xxxxxxxxx>
> ---
>  drivers/xen/manage.c                       |   12 ++++++------
>  drivers/xen/xenbus/xenbus_probe.c          |    2 +-
>  drivers/xen/xenbus/xenbus_probe_frontend.c |    8 +++++---
>  3 files changed, 12 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/xen/manage.c b/drivers/xen/manage.c
> index db8c4c4..3f76dcf 100644
> --- a/drivers/xen/manage.c
> +++ b/drivers/xen/manage.c
> @@ -63,7 +63,7 @@ static int xen_suspend(void *data)
>  
>       BUG_ON(!irqs_disabled());
>  
> -     err = sysdev_suspend(PMSG_SUSPEND);
> +     err = sysdev_suspend(PMSG_FREEZE);
>       if (err) {
>               printk(KERN_ERR "xen_suspend: sysdev_suspend failed: %d\n",
>                       err);
> @@ -114,16 +114,16 @@ static void do_suspend(void)
>       }
>  #endif
>  
> -     err = dpm_suspend_start(PMSG_SUSPEND);
> +     err = dpm_suspend_start(PMSG_FREEZE);
>       if (err) {
>               printk(KERN_ERR "xen suspend: dpm_suspend_start %d\n", err);
>               goto out_thaw;
>       }
>  
> -     printk(KERN_DEBUG "suspending xenstore...\n");
> +     /* printk(KERN_DEBUG "suspending xenstore...\n"); */
>       xs_suspend();
>  
> -     err = dpm_suspend_noirq(PMSG_SUSPEND);
> +     err = dpm_suspend_noirq(PMSG_FREEZE);
>       if (err) {
>               printk(KERN_ERR "dpm_suspend_noirq failed: %d\n", err);
>               goto out_resume;
> @@ -134,7 +134,7 @@ static void do_suspend(void)
>       else
>               err = stop_machine(xen_suspend, &cancelled, cpumask_of(0));
>  
> -     dpm_resume_noirq(PMSG_RESUME);
> +     dpm_resume_noirq(cancelled ? PMSG_THAW : PMSG_RESTORE);
>  
>       if (err) {
>               printk(KERN_ERR "failed to start xen_suspend: %d\n", err);
> @@ -148,7 +148,7 @@ out_resume:
>       } else
>               xs_suspend_cancel();
>  
> -     dpm_resume_end(PMSG_RESUME);
> +     dpm_resume_end(cancelled ? PMSG_THAW : PMSG_RESTORE);
>  
>       /* Make sure timer events get retriggered on all CPUs */
>       clock_was_set();
> diff --git a/drivers/xen/xenbus/xenbus_probe.c 
> b/drivers/xen/xenbus/xenbus_probe.c
> index 7397695..471ca48 100644
> --- a/drivers/xen/xenbus/xenbus_probe.c
> +++ b/drivers/xen/xenbus/xenbus_probe.c
> @@ -645,7 +645,7 @@ EXPORT_SYMBOL_GPL(xenbus_dev_resume);
>  int xenbus_dev_cancel(struct device *dev)
>  {
>       /* Do nothing */
> -     DPRINTK("cancel");
> +     /* DPRINTK("cancel"); */
>       return 0;
>  }
>  EXPORT_SYMBOL_GPL(xenbus_dev_cancel);
> diff --git a/drivers/xen/xenbus/xenbus_probe_frontend.c 
> b/drivers/xen/xenbus/xenbus_probe_frontend.c
> index 9ad8868..d6e5f0d 100644
> --- a/drivers/xen/xenbus/xenbus_probe_frontend.c
> +++ b/drivers/xen/xenbus/xenbus_probe_frontend.c
> @@ -86,9 +86,11 @@ static struct device_attribute xenbus_frontend_dev_attrs[] 
> = {
>  };
>  
>  static struct dev_pm_ops xenbus_pm_ops = {
> -     .suspend = xenbus_dev_suspend,
> -     .resume  = xenbus_dev_resume,
> -     .thaw  = xenbus_dev_cancel,
> +     .suspend        = xenbus_dev_suspend,
> +     .resume         = xenbus_dev_resume,
> +     .freeze         = xenbus_dev_suspend,
> +     .thaw           = xenbus_dev_cancel,
> +     .restore        = xenbus_dev_resume,
>  };
>  
>  static struct xen_bus_type xenbus_frontend = {



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