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>

1 files changed, 15 insertions, 15 deletions

diff --git a/arch/powerpc/platforms/pseries/hotplug-cpu.c b/arch/powerpc/platforms/pseries/hotplug-cpu.c
index 349e0af9389a..fefb7f84800b 100644
--- a/arch/powerpc/platforms/pseries/hotplug-cpu.c
+++ b/arch/powerpc/platforms/pseries/hotplug-cpu.c
@@ -140,25 +140,25 @@ 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()));
+                if (get_preferred_offline_state(cpu) == CPU_STATE_ONLINE) {
+                        unregister_slb_shadow(hwcpu, __pa(get_slb_shadow()));
 
-                /*
-                 * Call to start_secondary_resume() will not return.
-                 * Kernel stack will be reset and start_secondary()
-                 * will be called to continue the online operation.
-                 */
-                start_secondary_resume();
+                        /*
+                         * Call to start_secondary_resume() will not return.
+                         * Kernel stack will be reset and start_secondary()
+                         * 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()));
-                rtas_stop_self();
-        }
+        set_cpu_current_state(cpu, CPU_STATE_OFFLINE);
+        unregister_slb_shadow(hwcpu, __pa(get_slb_shadow()));
+        rtas_stop_self();
 
         /* Should never get here... */
         BUG();