MIPS: Add arch generic CPU hotplug
Each platform has to add support for CPU hotplugging itself by providing
suitable definitions for the cpu_disable and cpu_die of the smp_ops
methods and setting SYS_SUPPORTS_HOTPLUG_CPU. A platform should only set
SYS_SUPPORTS_HOTPLUG_CPU once all it's smp_ops definitions have the
necessary changes. This patch contains the changes to the dummy smp_ops
definition for uni-processor systems.
Parts of the code contributed by Cavium Inc.
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/arch/mips/kernel/process.c b/arch/mips/kernel/process.c
index 1eaaa45..c09d681 100644
--- a/arch/mips/kernel/process.c
+++ b/arch/mips/kernel/process.c
@@ -50,10 +50,15 @@
*/
void __noreturn cpu_idle(void)
{
+ int cpu;
+
+ /* CPU is going idle. */
+ cpu = smp_processor_id();
+
/* endless idle loop with no priority at all */
while (1) {
tick_nohz_stop_sched_tick(1);
- while (!need_resched()) {
+ while (!need_resched() && cpu_online(cpu)) {
#ifdef CONFIG_MIPS_MT_SMTC
extern void smtc_idle_loop_hook(void);
@@ -62,6 +67,12 @@
if (cpu_wait)
(*cpu_wait)();
}
+#ifdef CONFIG_HOTPLUG_CPU
+ if (!cpu_online(cpu) && !cpu_isset(cpu, cpu_callin_map) &&
+ (system_state == SYSTEM_RUNNING ||
+ system_state == SYSTEM_BOOTING))
+ play_dead();
+#endif
tick_nohz_restart_sched_tick();
preempt_enable_no_resched();
schedule();