swsusp: introduce restore platform operations

At least on some machines it is necessary to prepare the ACPI firmware for the
restoration of the system memory state from the hibernation image if the
"platform" mode of hibernation has been used.  Namely, in that cases we need
to disable the GPEs before replacing the "boot" kernel with the "frozen"
kernel (cf.  http://bugzilla.kernel.org/show_bug.cgi?id=7887).  After the
restore they will be re-enabled by hibernation_ops->finish(), but if the
restore fails, they have to be re-enabled by the restore code explicitly.

For this purpose we can introduce two additional hibernation operations,
called pre_restore() and restore_cleanup() and call them from the restore code
path.  Still, they should be called if the "platform" mode of hibernation has
been used, so we need to pass the information about the hibernation mode from
the "frozen" kernel to the "boot" kernel in the image header.

Apparently, we can't drop the disabling of GPEs before the restore because of
Bug #7887 .   We also can't do it unconditionally, because the GPEs wouldn't
have been enabled after a successful restore if the suspend had been done in
the 'shutdown' or 'reboot' mode.

In principle we could (and probably should) unconditionally disable the GPEs
before each snapshot creation *and* before the restore, but then we'd have to
unconditionally enable them after the snapshot creation as well as after the
restore (or restore failure)   Still, for this purpose we'd need to modify
acpi_enter_sleep_state_prep() and acpi_leave_sleep_state() and we'd have to
introduce some mechanism synchronizing the disablind/enabling of the GPEs with
the device drivers' .suspend()/.resume() routines and with
disable_/enable_nonboot_cpus().   However, this would have affected the
suspend (ie.  s2ram) code as well as the hibernation, which I'd like to avoid
in this patch series.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Cc: Nigel Cunningham <nigel@nigel.suspend2.net>
Cc: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

4 files changed, 72 insertions, 19 deletions

diff --git a/kernel/power/disk.c b/kernel/power/disk.c
index 47882bfa610e..fa3b43b7206d 100644
--- a/kernel/power/disk.c
+++ b/kernel/power/disk.c
@@ -54,7 +54,8 @@ static struct hibernation_ops *hibernation_ops;
 
 void hibernation_set_ops(struct hibernation_ops *ops)
 {
-	if (ops && !(ops->prepare && ops->enter && ops->finish)) {
+	if (ops && !(ops->prepare && ops->enter && ops->finish
+	    && ops->pre_restore && ops->restore_cleanup)) {
 		WARN_ON(1);
 		return;
 	}
@@ -92,6 +93,31 @@ static void platform_finish(int platform_mode)
 }
 
 /**
+ *	platform_pre_restore - prepare the platform for the restoration from a
+ *	hibernation image.  If the restore fails after this function has been
+ *	called, platform_restore_cleanup() must be called.
+ */
+
+static int platform_pre_restore(int platform_mode)
+{
+	return (platform_mode && hibernation_ops) ?
+		hibernation_ops->pre_restore() : 0;
+}
+
+/**
+ *	platform_restore_cleanup - switch the platform to the normal mode of
+ *	operation after a failing restore.  If platform_pre_restore() has been
+ *	called before the failing restore, this function must be called too,
+ *	regardless of the result of platform_pre_restore().
+ */
+
+static void platform_restore_cleanup(int platform_mode)
+{
+	if (platform_mode && hibernation_ops)
+		hibernation_ops->restore_cleanup();
+}
+
+/**
  *	hibernation_snapshot - quiesce devices and create the hibernation
  *	snapshot image.
  *	@platform_mode - if set, use the platform driver, if available, to
@@ -141,11 +167,13 @@ int hibernation_snapshot(int platform_mode)
 /**
  *	hibernation_restore - quiesce devices and restore the hibernation
  *	snapshot image.  If successful, control returns in hibernation_snaphot()
+ *	@platform_mode - if set, use the platform driver, if available, to
+ *			 prepare the platform frimware for the transition.
  *
  *	Must be called with pm_mutex held
  */
 
-int hibernation_restore(void)
+int hibernation_restore(int platform_mode)
 {
 	int error;
 
@@ -155,11 +183,14 @@ int hibernation_restore(void)
 	if (error)
 		goto Finish;
 
-	error = disable_nonboot_cpus();
-	if (!error)
-		error = swsusp_resume();
-
-	enable_nonboot_cpus();
+	error = platform_pre_restore(platform_mode);
+	if (!error) {
+		error = disable_nonboot_cpus();
+		if (!error)
+			error = swsusp_resume();
+		enable_nonboot_cpus();
+	}
+	platform_restore_cleanup(platform_mode);
  Finish:
 	device_resume();
 	resume_console();
@@ -260,8 +291,12 @@ int hibernate(void)
 	}
 	error = hibernation_snapshot(hibernation_mode == HIBERNATION_PLATFORM);
 	if (in_suspend && !error) {
+		unsigned int flags = 0;
+
+		if (hibernation_mode == HIBERNATION_PLATFORM)
+			flags |= SF_PLATFORM_MODE;
 		pr_debug("PM: writing image.\n");
-		error = swsusp_write();
+		error = swsusp_write(flags);
 		swsusp_free();
 		if (!error)
 			power_down();
@@ -295,6 +330,7 @@ int hibernate(void)
 static int software_resume(void)
 {
 	int error;
+	unsigned int flags;
 
 	mutex_lock(&pm_mutex);
 	if (!swsusp_resume_device) {
@@ -342,9 +378,9 @@ static int software_resume(void)
 
 	pr_debug("PM: Reading swsusp image.\n");
 
-	error = swsusp_read();
+	error = swsusp_read(&flags);
 	if (!error)
-		hibernation_restore();
+		hibernation_restore(flags & SF_PLATFORM_MODE);
 
 	printk(KERN_ERR "PM: Restore failed, recovering.\n");
 	swsusp_free();
diff --git a/kernel/power/power.h b/kernel/power/power.h
index 70c378b3f85a..eab3603b7caf 100644
--- a/kernel/power/power.h
+++ b/kernel/power/power.h
@@ -27,7 +27,7 @@ struct swsusp_info {
 
 /* kernel/power/disk.c */
 extern int hibernation_snapshot(int platform_mode);
-extern int hibernation_restore(void);
+extern int hibernation_restore(int platform_mode);
 extern int hibernation_platform_enter(void);
 #endif
 
@@ -155,13 +155,20 @@ extern sector_t alloc_swapdev_block(int swap);
 extern void free_all_swap_pages(int swap);
 extern int swsusp_swap_in_use(void);
 
+/*
+ * Flags that can be passed from the hibernatig hernel to the "boot" kernel in
+ * the image header.
+ */
+#define SF_PLATFORM_MODE	1
+
+/* kernel/power/disk.c */
 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(void);
-extern int swsusp_write(void);
+extern int swsusp_read(unsigned int *flags_p);
+extern int swsusp_write(unsigned int flags);
 extern void swsusp_close(void);
 extern int suspend_enter(suspend_state_t state);
 
diff --git a/kernel/power/swap.c b/kernel/power/swap.c
index 8b1a1b837145..917aba100575 100644
--- a/kernel/power/swap.c
+++ b/kernel/power/swap.c
@@ -33,8 +33,9 @@ extern char resume_file[];
 #define SWSUSP_SIG	"S1SUSPEND"
 
 struct swsusp_header {
-	char reserved[PAGE_SIZE - 20 - sizeof(sector_t)];
+	char reserved[PAGE_SIZE - 20 - sizeof(sector_t) - sizeof(int)];
 	sector_t image;
+	unsigned int flags;	/* Flags to pass to the "boot" kernel */
 	char	orig_sig[10];
 	char	sig[10];
 } __attribute__((packed));
@@ -138,7 +139,7 @@ static int wait_on_bio_chain(struct bio **bio_chain)
  * Saving part
  */
 
-static int mark_swapfiles(sector_t start)
+static int mark_swapfiles(sector_t start, unsigned int flags)
 {
 	int error;
 
@@ -148,6 +149,7 @@ static int mark_swapfiles(sector_t start)
 		memcpy(swsusp_header->orig_sig,swsusp_header->sig, 10);
 		memcpy(swsusp_header->sig,SWSUSP_SIG, 10);
 		swsusp_header->image = start;
+		swsusp_header->flags = flags;
 		error = bio_write_page(swsusp_resume_block,
 					swsusp_header, NULL);
 	} else {
@@ -369,6 +371,7 @@ static int enough_swap(unsigned int nr_pages)
 
 /**
  *	swsusp_write - Write entire image and metadata.
+ *	@flags: flags to pass to the "boot" kernel in the image header
  *
  *	It is important _NOT_ to umount filesystems at this point. We want
  *	them synced (in case something goes wrong) but we DO not want to mark
@@ -376,7 +379,7 @@ static int enough_swap(unsigned int nr_pages)
  *	correctly, we'll mark system clean, anyway.)
  */
 
-int swsusp_write(void)
+int swsusp_write(unsigned int flags)
 {
 	struct swap_map_handle handle;
 	struct snapshot_handle snapshot;
@@ -415,7 +418,7 @@ int swsusp_write(void)
 		if (!error) {
 			flush_swap_writer(&handle);
 			printk("S");
-			error = mark_swapfiles(start);
+			error = mark_swapfiles(start, flags);
 			printk("|\n");
 		}
 	}
@@ -540,13 +543,20 @@ static int load_image(struct swap_map_handle *handle,
 	return error;
 }
 
-int swsusp_read(void)
+/**
+ *	swsusp_read - read the hibernation image.
+ *	@flags_p: flags passed by the "frozen" kernel in the image header should
+ *		  be written into this memeory location
+ */
+
+int swsusp_read(unsigned int *flags_p)
 {
 	int error;
 	struct swap_map_handle handle;
 	struct snapshot_handle snapshot;
 	struct swsusp_info *header;
 
+	*flags_p = swsusp_header->flags;
 	if (IS_ERR(resume_bdev)) {
 		pr_debug("swsusp: block device not initialised\n");
 		return PTR_ERR(resume_bdev);
diff --git a/kernel/power/user.c b/kernel/power/user.c
index bfed3b924093..1f24f30b951b 100644
--- a/kernel/power/user.c
+++ b/kernel/power/user.c
@@ -188,7 +188,7 @@ static int snapshot_ioctl(struct inode *inode, struct file *filp,
 			error = -EPERM;
 			break;
 		}
-		error = hibernation_restore();
+		error = hibernation_restore(data->platform_suspend);
 		break;
 
 	case SNAPSHOT_FREE: