powerpc: Move checks in pseries_mach_cpu_die()

Rearrange condition checks for better code readability and
	prevention of possible race conditions when
	preferred_offline_state can potentially change during the
	execution of pseries_mach_cpu_die().  The patch will make
	pseries_mach_cpu_die() put cpu in one of the consistent states
	and not hit the run over BUG()
Signed-off-by: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>
Cc: Gautham R Shenoy <ego@in.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

arch/powerpc/platforms/pseries/hotplug-cpu.c

@@ -140,7 +140,6 @@ static void pseries_mach_cpu_die(void)
 		if (!get_lppaca()->shared_proc)
 			get_lppaca()->donate_dedicated_cpu = 0;
 		get_lppaca()->idle = 0;
-	}
 
 		if (get_preferred_offline_state(cpu) == CPU_STATE_ONLINE) {
 			unregister_slb_shadow(hwcpu, __pa(get_slb_shadow()));
@@ -151,14 +150,15 @@ static void pseries_mach_cpu_die(void)
 			 * will be called to continue the online operation.
 			 */
 			start_secondary_resume();
+		}
+	}
 
-	} else if (get_preferred_offline_state(cpu) == CPU_STATE_OFFLINE) {
+	/* Requested state is CPU_STATE_OFFLINE at this point */
+	WARN_ON(get_preferred_offline_state(cpu) != CPU_STATE_OFFLINE);
 
 	set_cpu_current_state(cpu, CPU_STATE_OFFLINE);
-		unregister_slb_shadow(hard_smp_processor_id(),
-					__pa(get_slb_shadow()));
+	unregister_slb_shadow(hwcpu, __pa(get_slb_shadow()));
 	rtas_stop_self();
-	}
 
 	/* Should never get here... */
 	BUG();