PM: Add missing syscore_suspend() and syscore_resume() calls

Device suspend/resume infrastructure is used not only by the suspend
and hibernate code in kernel/power, but also by APM, Xen and the
kexec jump feature. However, commit 40dc166cb5dddbd36aa4ad11c03915ea
(PM / Core: Introduce struct syscore_ops for core subsystems PM)
failed to add syscore_suspend() and syscore_resume() calls to that
code, which generally leads to breakage when the features in question
are used.

To fix this problem, add the missing syscore_suspend() and
syscore_resume() calls to arch/x86/kernel/apm_32.c, kernel/kexec.c
and drivers/xen/manage.c.

Signed-off-by: Rafael J. Wysocki <[e-mail]>
Acked-by: Greg Kroah-Hartman <[e-mail]>
Acked-by: Ian Campbell <[e-mail]>

arch/x86/kernel/apm_32.c

···
 #include <linux/kthread.h>
 #include <linux/jiffies.h>
 #include <linux/acpi.h>
+#include <linux/syscore_ops.h>
 
 #include <asm/system.h>
 #include <asm/uaccess.h>
···
 
 	local_irq_disable();
 	sysdev_suspend(PMSG_SUSPEND);
+	syscore_suspend();
 
 	local_irq_enable();
 
···
 		apm_error("suspend", err);
 	err = (err == APM_SUCCESS) ? 0 : -EIO;
 
+	syscore_resume();
 	sysdev_resume();
 	local_irq_enable();
 
···
 
 	local_irq_disable();
 	sysdev_suspend(PMSG_SUSPEND);
+	syscore_suspend();
 	local_irq_enable();
 
 	err = set_system_power_state(APM_STATE_STANDBY);
···
 		apm_error("standby", err);
 
 	local_irq_disable();
+	syscore_resume();
 	sysdev_resume();
 	local_irq_enable();
 

drivers/base/syscore.c

···
 
 	return ret;
 }
+EXPORT_SYMBOL_GPL(syscore_suspend);
 
 /**
  * syscore_resume - Execute all the registered system core resume callbacks.
···
 				"Interrupts enabled after %pF\n", ops->resume);
 		}
 }
+EXPORT_SYMBOL_GPL(syscore_resume);
 #endif /* CONFIG_PM_SLEEP */
 
 /**

drivers/xen/manage.c

···
 #include <linux/sysrq.h>
 #include <linux/stop_machine.h>
 #include <linux/freezer.h>
+#include <linux/syscore_ops.h>
 
 #include <xen/xen.h>
 #include <xen/xenbus.h>
···
 	BUG_ON(!irqs_disabled());
 
 	err = sysdev_suspend(PMSG_FREEZE);
+	if (!err) {
+		err = syscore_suspend();
+		if (err)
+			sysdev_resume();
+	}
 	if (err) {
-		printk(KERN_ERR "xen_suspend: sysdev_suspend failed: %d\n",
+		printk(KERN_ERR "xen_suspend: system core suspend failed: %d\n",
 			err);
 		return err;
 	}
···
 		xen_timer_resume();
 	}
 
+	syscore_resume();
 	sysdev_resume();
 
 	return 0;

kernel/kexec.c

···
 #include <linux/vmalloc.h>
 #include <linux/swap.h>
 #include <linux/kmsg_dump.h>
+#include <linux/syscore_ops.h>
 
 #include <asm/page.h>
 #include <asm/uaccess.h>
···
 		local_irq_disable();
 		/* Suspend system devices */
 		error = sysdev_suspend(PMSG_FREEZE);
+		if (!error) {
+			error = syscore_suspend();
+			if (error)
+				sysdev_resume();
+		}
 		if (error)
 			goto Enable_irqs;
 	} else
···
 
 #ifdef CONFIG_KEXEC_JUMP
 	if (kexec_image->preserve_context) {
+		syscore_resume();
 		sysdev_resume();
  Enable_irqs:
 		local_irq_enable();