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    Subject[PATCH -mm] Hibernation: Check if ACPI is enabled during restore in the right place
    Date
    From: Rafael J. Wysocki <rjw@sisk.pl>

    The following scenario leads to total confusion of the platform firmware on
    some boxes (eg. HPC nx6325):
    * Hibernate with ACPI enabled
    * Pass "acpi=off" to the boot kernel

    To prevent this from happening it's necessary to check if ACPI is enabled (and
    enable it if that's not the case) _right_ _after_ control has been transfered
    from the boot kernel to the image kernel, before device_power_up() is called
    (ie. with interrupts disabled).  Enabling ACPI after calling device_power_up()
    turns out to be insufficient.

    For this reason, introduce new hibernation callback ->leave() that will be
    executed before device_power_up() by the restored image kernel.  To make it
    work, it also is necessary to move swsusp_suspend() from swsusp.c to disk.c
    (it's name is changed to "create_image", which is more up to the point).

    Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
    ---
    drivers/acpi/sleep/main.c | 7 ++++-
    include/linux/suspend.h | 7 +++++
    kernel/power/disk.c | 58 +++++++++++++++++++++++++++++++++++++++++++++-
    kernel/power/power.h | 1
    kernel/power/swsusp.c | 33 --------------------------
    5 files changed, 70 insertions(+), 36 deletions(-)

    Index: linux-2.6.23-rc4-mm1/drivers/acpi/sleep/main.c
    ===================================================================
    --- linux-2.6.23-rc4-mm1.orig/drivers/acpi/sleep/main.c
    +++ linux-2.6.23-rc4-mm1/drivers/acpi/sleep/main.c
    @@ -231,13 +231,17 @@ static int acpi_hibernation_enter(void)
    return ACPI_SUCCESS(status) ? 0 : -EFAULT;
    }

    -static void acpi_hibernation_finish(void)
    +static void acpi_hibernation_leave(void)
    {
    /*
    * If ACPI is not enabled by the BIOS and the boot kernel, we need to
    * enable it here.
    */
    acpi_enable();
    +}
    +
    +static void acpi_hibernation_finish(void)
    +{
    acpi_leave_sleep_state(ACPI_STATE_S4);
    acpi_disable_wakeup_device(ACPI_STATE_S4);

    @@ -267,6 +271,7 @@ static struct platform_hibernation_ops a
    .finish = acpi_hibernation_finish,
    .prepare = acpi_hibernation_prepare,
    .enter = acpi_hibernation_enter,
    + .leave = acpi_hibernation_leave,
    .pre_restore = acpi_hibernation_pre_restore,
    .restore_cleanup = acpi_hibernation_restore_cleanup,
    };
    Index: linux-2.6.23-rc4-mm1/include/linux/suspend.h
    ===================================================================
    --- linux-2.6.23-rc4-mm1.orig/include/linux/suspend.h
    +++ linux-2.6.23-rc4-mm1/include/linux/suspend.h
    @@ -156,6 +156,12 @@ extern void mark_free_pages(struct zone
    * Called after the nonboot CPUs have been disabled and all of the low
    * level devices have been shut down (runs with IRQs off).
    *
    + * @leave: Perform the first stage of the cleanup after the system sleep state
    + * indicated by @set_target() has been left.
    + * Called right after the control has been passed from the boot kernel to
    + * the image kernel, before the nonboot CPUs are enabled and before devices
    + * are resumed. Executed with interrupts disabled.
    + *
    * @pre_restore: Prepare system for the restoration from a hibernation image.
    * Called right after devices have been frozen and before the nonboot
    * CPUs are disabled (runs with IRQs on).
    @@ -170,6 +176,7 @@ struct platform_hibernation_ops {
    void (*finish)(void);
    int (*prepare)(void);
    int (*enter)(void);
    + void (*leave)(void);
    int (*pre_restore)(void);
    void (*restore_cleanup)(void);
    };
    Index: linux-2.6.23-rc4-mm1/kernel/power/disk.c
    ===================================================================
    --- linux-2.6.23-rc4-mm1.orig/kernel/power/disk.c
    +++ linux-2.6.23-rc4-mm1/kernel/power/disk.c
    @@ -93,6 +93,17 @@ static int platform_pre_snapshot(int pla
    }

    /**
    + * platform_leave - prepare the machine for switching to the normal mode
    + * of operation using the platform driver (called with interrupts disabled)
    + */
    +
    +static void platform_leave(int platform_mode)
    +{
    + if (platform_mode && hibernation_ops)
    + hibernation_ops->leave();
    +}
    +
    +/**
    * platform_finish - switch the machine to the normal mode of operation
    * using the platform driver (must be called after platform_prepare())
    */
    @@ -129,6 +140,51 @@ static void platform_restore_cleanup(int
    }

    /**
    + * create_image - freeze devices that need to be frozen with interrupts
    + * off, create the hibernation image and thaw those devices. Control
    + * reappears in this routine after a restore.
    + */
    +
    +int create_image(int platform_mode)
    +{
    + int error;
    +
    + error = arch_prepare_suspend();
    + if (error)
    + return error;
    +
    + local_irq_disable();
    + /* At this point, device_suspend() has been called, but *not*
    + * device_power_down(). We *must* call device_power_down() now.
    + * Otherwise, drivers for some devices (e.g. interrupt controllers)
    + * become desynchronized with the actual state of the hardware
    + * at resume time, and evil weirdness ensues.
    + */
    + error = device_power_down(PMSG_FREEZE);
    + if (error) {
    + printk(KERN_ERR "Some devices failed to power down, "
    + KERN_ERR "aborting suspend\n");
    + goto Enable_irqs;
    + }
    +
    + save_processor_state();
    + error = swsusp_arch_suspend();
    + if (error)
    + printk(KERN_ERR "Error %d while creating the image\n", error);
    + /* Restore control flow magically appears here */
    + restore_processor_state();
    + if (!in_suspend)
    + platform_leave(platform_mode);
    + /* NOTE: device_power_up() is just a resume() for devices
    + * that suspended with irqs off ... no overall powerup.
    + */
    + device_power_up();
    + Enable_irqs:
    + local_irq_enable();
    + return error;
    +}
    +
    +/**
    * hibernation_snapshot - quiesce devices and create the hibernation
    * snapshot image.
    * @platform_mode - if set, use the platform driver, if available, to
    @@ -163,7 +219,7 @@ int hibernation_snapshot(int platform_mo
    if (!error) {
    if (hibernation_mode != HIBERNATION_TEST) {
    in_suspend = 1;
    - error = swsusp_suspend();
    + error = create_image(platform_mode);
    /* Control returns here after successful restore */
    } else {
    printk("swsusp debug: Waiting for 5 seconds.\n");
    Index: linux-2.6.23-rc4-mm1/kernel/power/power.h
    ===================================================================
    --- linux-2.6.23-rc4-mm1.orig/kernel/power/power.h
    +++ linux-2.6.23-rc4-mm1/kernel/power/power.h
    @@ -183,7 +183,6 @@ extern int swsusp_swap_in_use(void);
    extern int swsusp_check(void);
    extern int swsusp_shrink_memory(void);
    extern void swsusp_free(void);
    -extern int swsusp_suspend(void);
    extern int swsusp_resume(void);
    extern int swsusp_read(unsigned int *flags_p);
    extern int swsusp_write(unsigned int flags);
    Index: linux-2.6.23-rc4-mm1/kernel/power/swsusp.c
    ===================================================================
    --- linux-2.6.23-rc4-mm1.orig/kernel/power/swsusp.c
    +++ linux-2.6.23-rc4-mm1/kernel/power/swsusp.c
    @@ -270,39 +270,6 @@ int swsusp_shrink_memory(void)
    return 0;
    }

    -int swsusp_suspend(void)
    -{
    - int error;
    -
    - if ((error = arch_prepare_suspend()))
    - return error;
    -
    - local_irq_disable();
    - /* At this point, device_suspend() has been called, but *not*
    - * device_power_down(). We *must* device_power_down() now.
    - * Otherwise, drivers for some devices (e.g. interrupt controllers)
    - * become desynchronized with the actual state of the hardware
    - * at resume time, and evil weirdness ensues.
    - */
    - if ((error = device_power_down(PMSG_FREEZE))) {
    - printk(KERN_ERR "Some devices failed to power down, aborting suspend\n");
    - goto Enable_irqs;
    - }
    -
    - save_processor_state();
    - if ((error = swsusp_arch_suspend()))
    - printk(KERN_ERR "Error %d suspending\n", error);
    - /* Restore control flow magically appears here */
    - restore_processor_state();
    - /* NOTE: device_power_up() is just a resume() for devices
    - * that suspended with irqs off ... no overall powerup.
    - */
    - device_power_up();
    - Enable_irqs:
    - local_irq_enable();
    - return error;
    -}
    -
    int swsusp_resume(void)
    {
    int error;
    -
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