Re: [PATCH] Use freeze/thaw/restore PM events for Guest suspend/resume/checkpoint

[Shriram Rajagopalan <rshriram@cs.ubc.ca>]

On Mon, Feb 14, 2011 at 8:21 AM, Shriram Rajagopalan <rshriram@cs.ubc.ca> wrote:
> Use PM_FREEZE, PM_THAW and PM_RESTORE power events for
> suspend/resume functionality, instead of PM_SUSPEND and
> PM_RESUME. Use of these pm events also fixes the Xen Guest
> hangup when taking checkpoints. When a suspend event is cancelled
> (i.e. 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);
>
> Signed-off-by: Shriram Rajagopalan <rshriram@cs.ubc.ca>
> ---
>  drivers/net/xen-netfront.c                 |    2 +-
>  drivers/xen/manage.c                       |   12 ++++++------
>  drivers/xen/xenbus/xenbus_probe.c          |   11 +++++++++--
>  drivers/xen/xenbus/xenbus_probe.h          |    3 ++-
>  drivers/xen/xenbus/xenbus_probe_frontend.c |   10 ++++++++--
>  include/xen/xenbus.h                       |    2 +-
>  6 files changed, 27 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/net/xen-netfront.c b/drivers/net/xen-netfront.c
> index 3f71199..22c6288 100644
> --- a/drivers/net/xen-netfront.c
> +++ b/drivers/net/xen-netfront.c
> @@ -1293,7 +1293,7 @@ static void xennet_disconnect_backend(struct netfront_info *info)
>        info->rx.sring = NULL;
>  }
>
> -static int netfront_suspend(struct xenbus_device *dev, pm_message_t state)
> +static int netfront_suspend(struct xenbus_device *dev)
>  {
>        struct netfront_info *info = dev_get_drvdata(&dev->dev);
>        struct hrtimer *timer = &info->smart_poll.timer;
> diff --git a/drivers/xen/manage.c b/drivers/xen/manage.c
> index 0b50906..98c856b 100644
> --- a/drivers/xen/manage.c
> +++ b/drivers/xen/manage.c
> @@ -60,7 +60,7 @@ 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);
> @@ -117,16 +117,16 @@ 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;
> @@ -137,7 +137,7 @@ 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);
> @@ -151,7 +151,7 @@ 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 3a83ba2..b61b9f8 100644
> --- a/drivers/xen/xenbus/xenbus_probe.c
> +++ b/drivers/xen/xenbus/xenbus_probe.c
> @@ -575,7 +575,7 @@ void xenbus_dev_changed(const char *node, struct xen_bus_type *bus)
>  }
>  EXPORT_SYMBOL_GPL(xenbus_dev_changed);
>
> -int xenbus_dev_suspend(struct device *dev, pm_message_t state)
> +int xenbus_dev_suspend(struct device *dev)
>  {
>        int err = 0;
>        struct xenbus_driver *drv;
> @@ -587,7 +587,7 @@ int xenbus_dev_suspend(struct device *dev, pm_message_t state)
>                return 0;
>        drv = to_xenbus_driver(dev->driver);
>        if (drv->suspend)
> -               err = drv->suspend(xdev, state);
> +               err = drv->suspend(xdev);
>        if (err)
>                printk(KERN_WARNING
>                       "xenbus: suspend %s failed: %i\n", dev_name(dev), err);
> @@ -638,6 +638,13 @@ int xenbus_dev_resume(struct device *dev)
>  }
>  EXPORT_SYMBOL_GPL(xenbus_dev_resume);
>
> +int xenbus_dev_cancel(struct device *dev)
> +{
> +       /* Do nothing */
> +       return 0;
> +}
> +EXPORT_SYMBOL_GPL(xenbus_dev_cancel);
> +
>  /* A flag to determine if xenstored is 'ready' (i.e. has started) */
>  int xenstored_ready = 0;
>
> diff --git a/drivers/xen/xenbus/xenbus_probe.h b/drivers/xen/xenbus/xenbus_probe.h
> index 0e5fc4c..4019187 100644
> --- a/drivers/xen/xenbus/xenbus_probe.h
> +++ b/drivers/xen/xenbus/xenbus_probe.h
> @@ -62,8 +62,9 @@ extern void xenbus_dev_changed(const char *node, struct xen_bus_type *bus);
>
>  extern void xenbus_dev_shutdown(struct device *_dev);
>
> -extern int xenbus_dev_suspend(struct device *dev, pm_message_t state);
> +extern int xenbus_dev_suspend(struct device *dev);
>  extern int xenbus_dev_resume(struct device *dev);
> +extern int xenbus_dev_cancel(struct device *dev);
>
>  extern void xenbus_otherend_changed(struct xenbus_watch *watch,
>                                    const char **vec, unsigned int len,
> diff --git a/drivers/xen/xenbus/xenbus_probe_frontend.c b/drivers/xen/xenbus/xenbus_probe_frontend.c
> index 5413248..ff32ffb 100644
> --- a/drivers/xen/xenbus/xenbus_probe_frontend.c
> +++ b/drivers/xen/xenbus/xenbus_probe_frontend.c
> @@ -82,6 +82,13 @@ static struct device_attribute xenbus_frontend_dev_attrs[] = {
>        __ATTR_NULL
>  };
>
> +static struct dev_pm_ops xenbus_pm_ops = {
> +       .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 = {
>        .root = "device",
> @@ -98,8 +105,7 @@ static struct xen_bus_type xenbus_frontend = {
>                .shutdown = xenbus_dev_shutdown,
>                .dev_attrs= xenbus_frontend_dev_attrs,
>
> -               .suspend  = xenbus_dev_suspend,
> -               .resume   = xenbus_dev_resume,
> +               .pm       = &xenbus_pm_ops,
>        },
>  };
>
> diff --git a/include/xen/xenbus.h b/include/xen/xenbus.h
> index 542ca7c..23e7f25 100644
> --- a/include/xen/xenbus.h
> +++ b/include/xen/xenbus.h
> @@ -91,7 +91,7 @@ struct xenbus_driver {
>        void (*otherend_changed)(struct xenbus_device *dev,
>                                 enum xenbus_state backend_state);
>        int (*remove)(struct xenbus_device *dev);
> -       int (*suspend)(struct xenbus_device *dev, pm_message_t state);
> +       int (*suspend)(struct xenbus_device *dev);
>        int (*resume)(struct xenbus_device *dev);
>        int (*uevent)(struct xenbus_device *, struct kobj_uevent_env *);
>        struct device_driver driver;
>
>
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>

parts of this patch were based on Kazuhiro Suzuki's initial patch to fix the
same issue. Refer to
http://lists.xensource.com/archives/html/xen-devel/2011-02/msg00371.html
for further details.