2 files changed, 47 insertions, 0 deletions

diff --git a/drivers/base/cpu.c b/drivers/base/cpu.c
index 4259072f5bd0..2aef96f20b30 100644
--- a/drivers/base/cpu.c
+++ b/drivers/base/cpu.c
@@ -128,10 +128,54 @@ print_cpus_func(online);
 print_cpus_func(possible);
 print_cpus_func(present);
 
+/*
+ * Print values for NR_CPUS and offlined cpus
+ */
+static ssize_t print_cpus_kernel_max(struct sysdev_class *class, char *buf)
+{
+        int n = snprintf(buf, PAGE_SIZE-2, "%d\n", CONFIG_NR_CPUS - 1);
+        return n;
+}
+static SYSDEV_CLASS_ATTR(kernel_max, 0444, print_cpus_kernel_max, NULL);
+
+/* arch-optional setting to enable display of offline cpus >= nr_cpu_ids */
+unsigned int total_cpus;
+
+static ssize_t print_cpus_offline(struct sysdev_class *class, char *buf)
+{
+        int n = 0, len = PAGE_SIZE-2;
+        cpumask_var_t offline;
+
+        /* display offline cpus < nr_cpu_ids */
+        if (!alloc_cpumask_var(&offline, GFP_KERNEL))
+                return -ENOMEM;
+        cpumask_complement(offline, cpu_online_mask);
+        n = cpulist_scnprintf(buf, len, offline);
+        free_cpumask_var(offline);
+
+        /* display offline cpus >= nr_cpu_ids */
+        if (total_cpus && nr_cpu_ids < total_cpus) {
+                if (n && n < len)
+                        buf[n++] = ',';
+
+                if (nr_cpu_ids == total_cpus-1)
+                        n += snprintf(&buf[n], len - n, "%d", nr_cpu_ids);
+                else
+                        n += snprintf(&buf[n], len - n, "%d-%d",
+                                                      nr_cpu_ids, total_cpus-1);
+        }
+
+        n += snprintf(&buf[n], len - n, "\n");
+        return n;
+}
+static SYSDEV_CLASS_ATTR(offline, 0444, print_cpus_offline, NULL);
+
 static struct sysdev_class_attribute *cpu_state_attr[] = {
         &attr_online_map,
         &attr_possible_map,
         &attr_present_map,
+        &attr_kernel_max,
+        &attr_offline,
 };
 
 static int cpu_states_init(void)
diff --git a/include/linux/smp.h b/include/linux/smp.h
index 3f9a60043a97..0d5770c2e43a 100644
--- a/include/linux/smp.h
+++ b/include/linux/smp.h
@@ -21,6 +21,9 @@ struct call_single_data {
         u16 priv;
 };
 
+/* total number of cpus in this system (may exceed NR_CPUS) */
+extern unsigned int total_cpus;
+
 #ifdef CONFIG_SMP
 
 #include <linux/preempt.h>