PM: introduce hibernation and suspend notifiers

Make it possible to register hibernation and suspend notifiers, so that
subsystems can perform hibernation-related or suspend-related operations that
should not be carried out by device drivers' .suspend() and .resume()
routines.

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

kernel/power/disk.c

@@ -281,9 +281,16 @@ int hibernate(void)
 {
 	int error;
 
+	mutex_lock(&pm_mutex);
 	/* The snapshot device should not be opened while we're running */
-	if (!atomic_add_unless(&snapshot_device_available, -1, 0))
-		return -EBUSY;
+	if (!atomic_add_unless(&snapshot_device_available, -1, 0)) {
+		error = -EBUSY;
+		goto Unlock;
+	}
+
+	error = pm_notifier_call_chain(PM_HIBERNATION_PREPARE);
+	if (error)
+		goto Exit;
 
 	/* Allocate memory management structures */
 	error = create_basic_memory_bitmaps();
@@ -294,7 +301,6 @@ int hibernate(void)
 	if (error)
 		goto Finish;
 
-	mutex_lock(&pm_mutex);
 	if (hibernation_mode == HIBERNATION_TESTPROC) {
 		printk("swsusp debug: Waiting for 5 seconds.\n");
 		mdelay(5000);
@@ -316,12 +322,14 @@ int hibernate(void)
 		swsusp_free();
 	}
  Thaw:
-	mutex_unlock(&pm_mutex);
 	unprepare_processes();
  Finish:
 	free_basic_memory_bitmaps();
  Exit:
+	pm_notifier_call_chain(PM_POST_HIBERNATION);
 	atomic_inc(&snapshot_device_available);
+ Unlock:
+	mutex_unlock(&pm_mutex);
 	return error;
 }
 

kernel/power/main.c

@@ -23,6 +23,8 @@
 
 #include "power.h"
 
+BLOCKING_NOTIFIER_HEAD(pm_chain_head);
+
 /*This is just an arbitrary number */
 #define FREE_PAGE_NUMBER (100)
 
@@ -78,6 +80,10 @@ static int suspend_prepare(suspend_state_t state)
 	if (!pm_ops || !pm_ops->enter)
 		return -EPERM;
 
+	error = pm_notifier_call_chain(PM_SUSPEND_PREPARE);
+	if (error)
+		goto Finish;
+
 	pm_prepare_console();
 
 	if (freeze_processes()) {
@@ -125,6 +131,8 @@ static int suspend_prepare(suspend_state_t state)
  Thaw:
 	thaw_processes();
 	pm_restore_console();
+ Finish:
+	pm_notifier_call_chain(PM_POST_SUSPEND);
 	return error;
 }
 
@@ -176,6 +184,7 @@ static void suspend_finish(suspend_state_t state)
 	resume_console();
 	thaw_processes();
 	pm_restore_console();
+	pm_notifier_call_chain(PM_POST_SUSPEND);
 }
 
 

kernel/power/power.h

@@ -173,5 +173,15 @@ extern void swsusp_close(void);
 extern int suspend_enter(suspend_state_t state);
 
 struct timeval;
+/* kernel/power/swsusp.c */
 extern void swsusp_show_speed(struct timeval *, struct timeval *,
 				unsigned int, char *);
+
+/* kernel/power/main.c */
+extern struct blocking_notifier_head pm_chain_head;
+
+static inline int pm_notifier_call_chain(unsigned long val)
+{
+	return (blocking_notifier_call_chain(&pm_chain_head, val, NULL)
+			== NOTIFY_BAD) ? -EINVAL : 0;
+}

kernel/power/user.c

@@ -151,10 +151,14 @@ static int snapshot_ioctl(struct inode *inode, struct file *filp,
 		if (data->frozen)
 			break;
 		mutex_lock(&pm_mutex);
-		if (freeze_processes()) {
-			thaw_processes();
-			error = -EBUSY;
+		error = pm_notifier_call_chain(PM_HIBERNATION_PREPARE);
+		if (!error) {
+			error = freeze_processes();
+			if (error)
+				thaw_processes();
 		}
+		if (error)
+			pm_notifier_call_chain(PM_POST_HIBERNATION);
 		mutex_unlock(&pm_mutex);
 		if (!error)
 			data->frozen = 1;
@@ -165,6 +169,7 @@ static int snapshot_ioctl(struct inode *inode, struct file *filp,
 			break;
 		mutex_lock(&pm_mutex);
 		thaw_processes();
+		pm_notifier_call_chain(PM_POST_HIBERNATION);
 		mutex_unlock(&pm_mutex);
 		data->frozen = 0;
 		break;