MIPS: SMP: Move the AP sync point before the non-parallel aware functions

When CONFIG_HOTPLUG_PARALLEL is enabled, the code executing before
cpuhp_ap_sync_alive() is executed in parallel, while after it is
serialized. The functions set_cpu_sibling_map() and set_cpu_core_map()
were not designed to be executed in parallel, so by moving the
cpuhp_ap_sync_alive() before cpuhp_ap_sync_alive(), we then ensure
they will be called serialized.

The measurement done on EyeQ5 did not show any relevant boot time
increase after applying this patch.

Fixes: 76c43eb ("MIPS: SMP: Implement parallel CPU bring up for EyeQ")
Reported-by: Huacai Chen <[email protected]>
Signed-off-by: Gregory CLEMENT <[email protected]>
Signed-off-by: Thomas Bogendoerfer <[email protected]>

Author: gclement

arch/mips/kernel/smp.c

@@ -374,13 +374,13 @@ asmlinkage void start_secondary(void)
 	calibrate_delay();
 	cpu_data[cpu].udelay_val = loops_per_jiffy;
 
+#ifdef CONFIG_HOTPLUG_PARALLEL
+	cpuhp_ap_sync_alive();
+#endif
 	set_cpu_sibling_map(cpu);
 	set_cpu_core_map(cpu);
 
 	cpumask_set_cpu(cpu, &cpu_coherent_mask);
-#ifdef CONFIG_HOTPLUG_PARALLEL
-	cpuhp_ap_sync_alive();
-#endif
 	notify_cpu_starting(cpu);
 
 #ifndef CONFIG_HOTPLUG_PARALLEL