Merge branch 'x86-cpu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 cpu offlining patch from Ingo Molnar:
 "This tree includes a single commit that speeds up x86 suspend/resume
  by replacing a naive 100msec sleep based polling loop with proper
  completion notification.

  This gives some real suspend/resume benefit on servers with larger
  core counts"

* 'x86-cpu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/smpboot: Speed up suspend/resume by avoiding 100ms sleep for CPU offline during S3

1 files changed, 12 insertions, 11 deletions

diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 1c3443d98105..2d5200e56357 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -102,6 +102,8 @@ DEFINE_PER_CPU_READ_MOSTLY(cpumask_var_t, cpu_llc_shared_map);
 DEFINE_PER_CPU_SHARED_ALIGNED(struct cpuinfo_x86, cpu_info);
 EXPORT_PER_CPU_SYMBOL(cpu_info);
 
+static DEFINE_PER_CPU(struct completion, die_complete);
+
 atomic_t init_deasserted;
 
 /*
@@ -1325,26 +1327,24 @@ int native_cpu_disable(void)
                 return ret;
 
         clear_local_APIC();
-
+        init_completion(&per_cpu(die_complete, smp_processor_id()));
         cpu_disable_common();
+
         return 0;
 }
 
 void native_cpu_die(unsigned int cpu)
 {
         /* We don't do anything here: idle task is faking death itself. */
-        unsigned int i;
+        wait_for_completion_timeout(&per_cpu(die_complete, cpu), HZ);
 
-        for (i = 0; i < 10; i++) {
-                /* They ack this in play_dead by setting CPU_DEAD */
-                if (per_cpu(cpu_state, cpu) == CPU_DEAD) {
-                        if (system_state == SYSTEM_RUNNING)
-                                pr_info("CPU %u is now offline\n", cpu);
-                        return;
-                }
-                msleep(100);
+        /* They ack this in play_dead() by setting CPU_DEAD */
+        if (per_cpu(cpu_state, cpu) == CPU_DEAD) {
+                if (system_state == SYSTEM_RUNNING)
+                        pr_info("CPU %u is now offline\n", cpu);
+        } else {
+                pr_err("CPU %u didn't die...\n", cpu);
         }
-        pr_err("CPU %u didn't die...\n", cpu);
 }
 
 void play_dead_common(void)
@@ -1356,6 +1356,7 @@ void play_dead_common(void)
         mb();
         /* Ack it */
         __this_cpu_write(cpu_state, CPU_DEAD);
+        complete(&per_cpu(die_complete, smp_processor_id()));
 
         /*
          * With physical CPU hotplug, we should halt the cpu