[S390] vdso: fix per cpu area allocation

[pandora-kernel.git] / arch / s390 / kernel / smp.c

diff --git a/arch/s390/kernel/smp.c b/arch/s390/kernel/smp.c
index fd8e311..be2cae0 100644 (file)
--- a/arch/s390/kernel/smp.c
+++ b/arch/s390/kernel/smp.c
@@ -687,13 +687,14 @@ void __init smp_prepare_cpus(unsigned int max_cpus)
 #ifndef CONFIG_64BIT
        if (MACHINE_HAS_IEEE)
                lowcore->extended_save_area_addr = (u32) save_area;
-#else
-       if (vdso_alloc_per_cpu(smp_processor_id(), lowcore))
-               BUG();
 #endif
        set_prefix((u32)(unsigned long) lowcore);
        local_mcck_enable();
        local_irq_enable();
+#ifdef CONFIG_64BIT
+       if (vdso_alloc_per_cpu(smp_processor_id(), &S390_lowcore))
+               BUG();
+#endif
        for_each_possible_cpu(cpu)
                if (cpu != smp_processor_id())
                        smp_create_idle(cpu);
@@ -856,13 +857,20 @@ static ssize_t show_idle_count(struct sys_device *dev,
 {
        struct s390_idle_data *idle;
        unsigned long long idle_count;
+       unsigned int sequence;
 
        idle = &per_cpu(s390_idle, dev->id);
-       spin_lock(&idle->lock);
+repeat:
+       sequence = idle->sequence;
+       smp_rmb();
+       if (sequence & 1)
+               goto repeat;
        idle_count = idle->idle_count;
        if (idle->idle_enter)
                idle_count++;
-       spin_unlock(&idle->lock);
+       smp_rmb();
+       if (idle->sequence != sequence)
+               goto repeat;
        return sprintf(buf, "%llu\n", idle_count);
 }
 static SYSDEV_ATTR(idle_count, 0444, show_idle_count, NULL);
@@ -872,15 +880,22 @@ static ssize_t show_idle_time(struct sys_device *dev,
 {
        struct s390_idle_data *idle;
        unsigned long long now, idle_time, idle_enter;
+       unsigned int sequence;
 
        idle = &per_cpu(s390_idle, dev->id);
-       spin_lock(&idle->lock);
        now = get_clock();
+repeat:
+       sequence = idle->sequence;
+       smp_rmb();
+       if (sequence & 1)
+               goto repeat;
        idle_time = idle->idle_time;
        idle_enter = idle->idle_enter;
        if (idle_enter != 0ULL && idle_enter < now)
                idle_time += now - idle_enter;
-       spin_unlock(&idle->lock);
+       smp_rmb();
+       if (idle->sequence != sequence)
+               goto repeat;
        return sprintf(buf, "%llu\n", idle_time >> 12);
 }
 static SYSDEV_ATTR(idle_time_us, 0444, show_idle_time, NULL);
@@ -908,11 +923,7 @@ static int __cpuinit smp_cpu_notify(struct notifier_block *self,
        case CPU_ONLINE:
        case CPU_ONLINE_FROZEN:
                idle = &per_cpu(s390_idle, cpu);
-               spin_lock_irq(&idle->lock);
-               idle->idle_enter = 0;
-               idle->idle_time = 0;
-               idle->idle_count = 0;
-               spin_unlock_irq(&idle->lock);
+               memset(idle, 0, sizeof(struct s390_idle_data));
                if (sysfs_create_group(&s->kobj, &cpu_online_attr_group))
                        return NOTIFY_BAD;
                break;