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, 14 insertions, 20 deletions

diff --git a/arch/x86/kernel/microcode_core.c b/arch/x86/kernel/microcode_core.c
index 87af68e..5ed0ab5 100644
--- a/arch/x86/kernel/microcode_core.c
+++ b/arch/x86/kernel/microcode_core.c
@@ -82,6 +82,7 @@
 #include <linux/cpu.h>
 #include <linux/fs.h>
 #include <linux/mm.h>
+#include <linux/syscore_ops.h>
 
 #include <asm/microcode.h>
 #include <asm/processor.h>
@@ -438,33 +439,25 @@ static int mc_sysdev_remove(struct sys_device *sys_dev)
 	return 0;
 }
 
-static int mc_sysdev_resume(struct sys_device *dev)
+static struct sysdev_driver mc_sysdev_driver = {
+	.add			= mc_sysdev_add,
+	.remove			= mc_sysdev_remove,
+};
+
+/**
+ * mc_bp_resume - Update boot CPU microcode during resume.
+ */
+static void mc_bp_resume(void)
 {
-	int cpu = dev->id;
+	int cpu = smp_processor_id();
 	struct ucode_cpu_info *uci = ucode_cpu_info + cpu;
 
-	if (!cpu_online(cpu))
-		return 0;
-
-	/*
-	 * All non-bootup cpus are still disabled,
-	 * so only CPU 0 will apply ucode here.
-	 *
-	 * Moreover, there can be no concurrent
-	 * updates from any other places at this point.
-	 */
-	WARN_ON(cpu != 0);
-
 	if (uci->valid && uci->mc)
 		microcode_ops->apply_microcode(cpu);
-
-	return 0;
 }
 
-static struct sysdev_driver mc_sysdev_driver = {
-	.add			= mc_sysdev_add,
-	.remove			= mc_sysdev_remove,
-	.resume			= mc_sysdev_resume,
+static struct syscore_ops mc_syscore_ops = {
+	.resume			= mc_bp_resume,
 };
 
 static __cpuinit int
@@ -542,6 +535,7 @@ static int __init microcode_init(void)
 	if (error)
 		return error;
 
+	register_syscore_ops(&mc_syscore_ops);
 	register_hotcpu_notifier(&mc_cpu_notifier);
 
 	pr_info("Microcode Update Driver: v" MICROCODE_VERSION