powerpc/kdump: Stop all other CPUs before running crash handlers

During kdump we run the crash handlers first then stop all other CPUs.
We really want to stop all CPUs as close to the fail as possible and also
have a very controlled environment for running the crash handlers, so it
makes sense to reverse the order.
Signed-off-by: Anton Blanchard <anton@samba.org>
Acked-by: Matt Evans <matt@ozlabs.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

arch/powerpc/kernel/crash.c

@@ -402,6 +402,18 @@ void default_machine_crash_shutdown(struct pt_regs *regs)
 	 */
 	hard_irq_disable();
 
+	/*
+	 * Make a note of crashing cpu. Will be used in machine_kexec
+	 * such that another IPI will not be sent.
+	 */
+	crashing_cpu = smp_processor_id();
+	crash_save_cpu(regs, crashing_cpu);
+	crash_kexec_prepare_cpus(crashing_cpu);
+	cpu_set(crashing_cpu, cpus_in_crash);
+#if defined(CONFIG_PPC_STD_MMU_64) && defined(CONFIG_SMP)
+	crash_kexec_wait_realmode(crashing_cpu);
+#endif
+
 	for_each_irq(i) {
 		struct irq_desc *desc = irq_to_desc(i);
 
@@ -438,18 +450,8 @@ void default_machine_crash_shutdown(struct pt_regs *regs)
 	crash_shutdown_cpu = -1;
 	__debugger_fault_handler = old_handler;
 
-	/*
-	 * Make a note of crashing cpu. Will be used in machine_kexec
-	 * such that another IPI will not be sent.
-	 */
-	crashing_cpu = smp_processor_id();
-	crash_save_cpu(regs, crashing_cpu);
-	crash_kexec_prepare_cpus(crashing_cpu);
-	cpu_set(crashing_cpu, cpus_in_crash);
 	crash_kexec_stop_spus();
-#if defined(CONFIG_PPC_STD_MMU_64) && defined(CONFIG_SMP)
-	crash_kexec_wait_realmode(crashing_cpu);
-#endif
+
 	if (ppc_md.kexec_cpu_down)
 		ppc_md.kexec_cpu_down(1, 0);
 }