[PATCH] PM / Hibernate: Introduce CONFIG_HIBERNATE_INTERFACE

["Rafael J. Wysocki" <rjw@sisk.pl>]

From: Rafael J. Wysocki <rjw@sisk.pl>

Xen save/restore is going to use hibernate device callbacks for
quiescing devices and putting them back to normal operations and it
would need to select CONFIG_HIBERNATION for this purpose.  However,
that also would cause the hibernate interfaces for user space to be
enabled, which might confuse user space, because the Xen kernels
don't support hibernation.  Moreover, it would be wasteful, as it
would make the Xen kernels include a substantial amount of code that
they would never use.

To address this issue introduce new power management Kconfig option
CONFIG_HIBERNATE_INTERFACE, such that the hibernate interfaces for
user space and the image-handling code will depend on it and it will
select CONFIG_HIBERNATION.  Then, Xen save/restore will be able to
select CONFIG_HIBERNATION without dragging the entire hibernate code
along with it.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Tested-by: Shriram Rajagopalan <rshriram@cs.ubc.ca>
---
 arch/x86/power/Makefile |    3 ++-
 include/linux/suspend.h |   15 +++++----------
 kernel/power/Kconfig    |    4 ++++
 kernel/power/Makefile   |    4 ++--
 kernel/power/main.c     |    2 +-
 kernel/power/power.h    |    6 +++---
 6 files changed, 17 insertions(+), 17 deletions(-)

Index: linux-2.6/kernel/power/Kconfig
===================================================================
--- linux-2.6.orig/kernel/power/Kconfig
+++ linux-2.6/kernel/power/Kconfig
@@ -19,8 +19,12 @@ config SUSPEND_FREEZER
 	  Turning OFF this setting is NOT recommended! If in doubt, say Y.
 
 config HIBERNATION
+	bool
+
+config HIBERNATE_INTERFACE
 	bool "Hibernation (aka 'suspend to disk')"
 	depends on SWAP && ARCH_HIBERNATION_POSSIBLE
+	select HIBERNATION
 	select LZO_COMPRESS
 	select LZO_DECOMPRESS
 	---help---
Index: linux-2.6/kernel/power/Makefile
===================================================================
--- linux-2.6.orig/kernel/power/Makefile
+++ linux-2.6/kernel/power/Makefile
@@ -6,7 +6,7 @@ obj-$(CONFIG_PM_SLEEP)		+= console.o
 obj-$(CONFIG_FREEZER)		+= process.o
 obj-$(CONFIG_SUSPEND)		+= suspend.o
 obj-$(CONFIG_PM_TEST_SUSPEND)	+= suspend_test.o
-obj-$(CONFIG_HIBERNATION)	+= hibernate.o snapshot.o swap.o user.o \
-				   block_io.o
+obj-$(CONFIG_HIBERNATE_INTERFACE)	+= hibernate.o snapshot.o swap.o \
+						user.o block_io.o
 
 obj-$(CONFIG_MAGIC_SYSRQ)	+= poweroff.o
Index: linux-2.6/include/linux/suspend.h
===================================================================
--- linux-2.6.orig/include/linux/suspend.h
+++ linux-2.6/include/linux/suspend.h
@@ -229,7 +229,7 @@ struct platform_hibernation_ops {
 	void (*recover)(void);
 };
 
-#ifdef CONFIG_HIBERNATION
+#ifdef CONFIG_HIBERNATE_INTERFACE
 /* kernel/power/snapshot.c */
 extern void __register_nosave_region(unsigned long b, unsigned long e, int km);
 static inline void __init register_nosave_region(unsigned long b, unsigned long e)
@@ -248,7 +248,9 @@ extern unsigned long get_safe_page(gfp_t
 extern void hibernation_set_ops(const struct platform_hibernation_ops *ops);
 extern int hibernate(void);
 extern bool system_entering_hibernation(void);
-#else /* CONFIG_HIBERNATION */
+#else /* !CONFIG_HIBERNATE_INTERFACE */
+static inline void register_nosave_region(unsigned long b, unsigned long e) {}
+static inline void register_nosave_region_late(unsigned long b, unsigned long e) {}
 static inline int swsusp_page_is_forbidden(struct page *p) { return 0; }
 static inline void swsusp_set_page_free(struct page *p) {}
 static inline void swsusp_unset_page_free(struct page *p) {}
@@ -256,7 +258,7 @@ static inline void swsusp_unset_page_fre
 static inline void hibernation_set_ops(const struct platform_hibernation_ops *ops) {}
 static inline int hibernate(void) { return -ENOSYS; }
 static inline bool system_entering_hibernation(void) { return false; }
-#endif /* CONFIG_HIBERNATION */
+#endif /* !CONFIG_HIBERNATE_INTERFACE */
 
 #ifdef CONFIG_PM_SLEEP
 void save_processor_state(void);
@@ -298,13 +300,6 @@ static inline bool pm_wakeup_pending(voi
 extern struct mutex pm_mutex;
 
 #ifndef CONFIG_HIBERNATION
-static inline void register_nosave_region(unsigned long b, unsigned long e)
-{
-}
-static inline void register_nosave_region_late(unsigned long b, unsigned long e)
-{
-}
-
 static inline void lock_system_sleep(void) {}
 static inline void unlock_system_sleep(void) {}
 
Index: linux-2.6/arch/x86/power/Makefile
===================================================================
--- linux-2.6.orig/arch/x86/power/Makefile
+++ linux-2.6/arch/x86/power/Makefile
@@ -4,4 +4,5 @@ nostackp := $(call cc-option, -fno-stack
 CFLAGS_cpu.o	:= $(nostackp)
 
 obj-$(CONFIG_PM_SLEEP)		+= cpu.o
-obj-$(CONFIG_HIBERNATION)	+= hibernate_$(BITS).o hibernate_asm_$(BITS).o
+obj-$(CONFIG_HIBERNATE_INTERFACE)	+= hibernate_$(BITS).o \
+						hibernate_asm_$(BITS).o
Index: linux-2.6/kernel/power/main.c
===================================================================
--- linux-2.6.orig/kernel/power/main.c
+++ linux-2.6/kernel/power/main.c
@@ -156,7 +156,7 @@ static ssize_t state_show(struct kobject
 			s += sprintf(s,"%s ", pm_states[i]);
 	}
 #endif
-#ifdef CONFIG_HIBERNATION
+#ifdef CONFIG_HIBERNATE_INTERFACE
 	s += sprintf(s, "%s\n", "disk");
 #else
 	if (s != buf)
Index: linux-2.6/kernel/power/power.h
===================================================================
--- linux-2.6.orig/kernel/power/power.h
+++ linux-2.6/kernel/power/power.h
@@ -13,7 +13,7 @@ struct swsusp_info {
 	unsigned long		size;
 } __attribute__((aligned(PAGE_SIZE)));
 
-#ifdef CONFIG_HIBERNATION
+#ifdef CONFIG_HIBERNATE_INTERFACE
 /* kernel/power/snapshot.c */
 extern void __init hibernate_image_size_init(void);
 
@@ -53,10 +53,10 @@ extern int hibernation_snapshot(int plat
 extern int hibernation_restore(int platform_mode);
 extern int hibernation_platform_enter(void);
 
-#else /* !CONFIG_HIBERNATION */
+#else /* !CONFIG_HIBERNATE_INTERFACE */
 
 static inline void hibernate_image_size_init(void) {}
-#endif /* !CONFIG_HIBERNATION */
+#endif /* !CONFIG_HIBERNATE_INTERFACE */
 
 extern int pfn_is_nosave(unsigned long);