Hibernation: Check if ACPI is enabled during restore in the right place

The following scenario leads to total confusion of the platform firmware on
some boxes (eg. HPC nx6325):
* Hibernate with ACPI enabled
* Resume passing "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>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 57 insertions, 1 deletions

diff --git a/kernel/power/disk.c b/kernel/power/disk.c
index 555c0f0b2f7..e50f4da18fd 100644
--- a/kernel/power/disk.c
+++ b/kernel/power/disk.c
@@ -93,6 +93,17 @@ static int platform_pre_snapshot(int platform_mode)
 }
 
 /**
+ *	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 platform_mode)
 }
 
 /**
+ *	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_mode)
 	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");