[PATCH] Check if cpu can be onlined before calling smp_prepare_cpu()

- Moved check for online cpu out of smp_prepare_cpu()

- Moved default declaration of smp_prepare_cpu() to kernel/cpu.c

- Removed lock_cpu_hotplug() from smp_prepare_cpu() to around it, since
  its called from cpu_up() as well now.

- Removed clearing from cpu_present_map during cpu_offline as it breaks
  using cpu_up() directly during a subsequent online operation.

Signed-off-by: Ashok Raj <ashok.raj@intel.com>
Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com>
Cc: "Li, Shaohua" <shaohua.li@intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

kernel/power/smp.c

@@ -49,9 +49,7 @@ void enable_nonboot_cpus(void)
 
 	printk("Thawing cpus ...\n");
 	for_each_cpu_mask(cpu, frozen_cpus) {
-		error = smp_prepare_cpu(cpu);
-		if (!error)
-			error = cpu_up(cpu);
+		error = cpu_up(cpu);
 		if (!error) {
 			printk("CPU%d is up\n", cpu);
 			continue;