x86: Use syscore_ops instead of sysdev classes and sysdevs

Some subsystems in the x86 tree need to carry out suspend/resume and
shutdown operations with one CPU on-line and interrupts disabled and
they define sysdev classes and sysdevs or sysdev drivers for this
purpose.  This leads to unnecessarily complicated code and excessive
memory usage, so switch them to using struct syscore_ops objects for
this purpose instead.

Generally, there are three categories of subsystems that use
sysdevs for implementing PM operations: (1) subsystems whose
suspend/resume callbacks ignore their arguments entirely (the
majority), (2) subsystems whose suspend/resume callbacks use their
struct sys_device argument, but don't really need to do that,
because they can be implemented differently in an arguably simpler
way (io_apic.c), and (3) subsystems whose suspend/resume callbacks
use their struct sys_device argument, but the value of that argument
is always the same and could be ignored (microcode_core.c).  In all
of these cases the subsystems in question may be readily converted to
using struct syscore_ops objects for power management and shutdown.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 12 insertions, 32 deletions

diff --git a/arch/x86/oprofile/nmi_int.c b/arch/x86/oprofile/nmi_int.c
index e2b7b0c..8dace18 100644
--- a/arch/x86/oprofile/nmi_int.c
+++ b/arch/x86/oprofile/nmi_int.c
@@ -15,7 +15,7 @@
 #include <linux/notifier.h>
 #include <linux/smp.h>
 #include <linux/oprofile.h>
-#include <linux/sysdev.h>
+#include <linux/syscore_ops.h>
 #include <linux/slab.h>
 #include <linux/moduleparam.h>
 #include <linux/kdebug.h>
@@ -536,7 +536,7 @@ static void nmi_shutdown(void)
 
 #ifdef CONFIG_PM
 
-static int nmi_suspend(struct sys_device *dev, pm_message_t state)
+static int nmi_suspend(void)
 {
 	/* Only one CPU left, just stop that one */
 	if (nmi_enabled == 1)
@@ -544,49 +544,31 @@ static int nmi_suspend(struct sys_device *dev, pm_message_t state)
 	return 0;
 }
 
-static int nmi_resume(struct sys_device *dev)
+static void nmi_resume(void)
 {
 	if (nmi_enabled == 1)
 		nmi_cpu_start(NULL);
-	return 0;
 }
 
-static struct sysdev_class oprofile_sysclass = {
-	.name		= "oprofile",
+static struct syscore_ops oprofile_syscore_ops = {
 	.resume		= nmi_resume,
 	.suspend	= nmi_suspend,
 };
 
-static struct sys_device device_oprofile = {
-	.id	= 0,
-	.cls	= &oprofile_sysclass,
-};
-
-static int __init init_sysfs(void)
+static void __init init_suspend_resume(void)
 {
-	int error;
-
-	error = sysdev_class_register(&oprofile_sysclass);
-	if (error)
-		return error;
-
-	error = sysdev_register(&device_oprofile);
-	if (error)
-		sysdev_class_unregister(&oprofile_sysclass);
-
-	return error;
+	register_syscore_ops(&oprofile_syscore_ops);
 }
 
-static void exit_sysfs(void)
+static void exit_suspend_resume(void)
 {
-	sysdev_unregister(&device_oprofile);
-	sysdev_class_unregister(&oprofile_sysclass);
+	unregister_syscore_ops(&oprofile_syscore_ops);
 }
 
 #else
 
-static inline int  init_sysfs(void) { return 0; }
-static inline void exit_sysfs(void) { }
+static inline void init_suspend_resume(void) { }
+static inline void exit_suspend_resume(void) { }
 
 #endif /* CONFIG_PM */
 
@@ -789,9 +771,7 @@ int __init op_nmi_init(struct oprofile_operations *ops)
 
 	mux_init(ops);
 
-	ret = init_sysfs();
-	if (ret)
-		return ret;
+	init_suspend_resume();
 
 	printk(KERN_INFO "oprofile: using NMI interrupt.\n");
 	return 0;
@@ -799,5 +779,5 @@ int __init op_nmi_init(struct oprofile_operations *ops)
 
 void op_nmi_exit(void)
 {
-	exit_sysfs();
+	exit_suspend_resume();
 }