cpu masks: optimize and clean up cpumask_of_cpu()

[linux-2.6] / kernel / cpu.c

diff --git a/kernel/cpu.c b/kernel/cpu.c
index b11f06dc149add3a29c072e2ec9356499dd9dbc1..06a8358bb4186018324e2c6b8d995140a2066992 100644 (file)
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -64,6 +64,8 @@ void __init cpu_hotplug_init(void)
        cpu_hotplug.refcount = 0;
 }
 
+cpumask_t cpu_active_map;
+
 #ifdef CONFIG_HOTPLUG_CPU
 
 void get_online_cpus(void)
@@ -283,6 +285,11 @@ out_allowed:
        set_cpus_allowed_ptr(current, &old_allowed);
 out_release:
        cpu_hotplug_done();
+       if (!err) {
+               if (raw_notifier_call_chain(&cpu_chain, CPU_POST_DEAD | mod,
+                                           hcpu) == NOTIFY_BAD)
+                       BUG();
+       }
        return err;
 }
 
@@ -291,14 +298,34 @@ int __ref cpu_down(unsigned int cpu)
        int err = 0;
 
        cpu_maps_update_begin();
-       if (cpu_hotplug_disabled)
+
+       if (cpu_hotplug_disabled) {
                err = -EBUSY;
-       else
-               err = _cpu_down(cpu, 0);
+               goto out;
+       }
+
+       cpu_clear(cpu, cpu_active_map);
 
+       /*
+        * Make sure the all cpus did the reschedule and are not
+        * using stale version of the cpu_active_map.
+        * This is not strictly necessary becuase stop_machine()
+        * that we run down the line already provides the required
+        * synchronization. But it's really a side effect and we do not
+        * want to depend on the innards of the stop_machine here.
+        */
+       synchronize_sched();
+
+       err = _cpu_down(cpu, 0);
+
+       if (cpu_online(cpu))
+               cpu_set(cpu, cpu_active_map);
+
+out:
        cpu_maps_update_done();
        return err;
 }
+EXPORT_SYMBOL(cpu_down);
 #endif /*CONFIG_HOTPLUG_CPU*/
 
 /* Requires cpu_add_remove_lock to be held */
@@ -354,11 +381,18 @@ int __cpuinit cpu_up(unsigned int cpu)
        }
 
        cpu_maps_update_begin();
-       if (cpu_hotplug_disabled)
+
+       if (cpu_hotplug_disabled) {
                err = -EBUSY;
-       else
-               err = _cpu_up(cpu, 0);
+               goto out;
+       }
+
+       err = _cpu_up(cpu, 0);
+
+       if (cpu_online(cpu))
+               cpu_set(cpu, cpu_active_map);
 
+out:
        cpu_maps_update_done();
        return err;
 }
@@ -412,7 +446,7 @@ void __ref enable_nonboot_cpus(void)
                goto out;
 
        printk("Enabling non-boot CPUs ...\n");
-       for_each_cpu_mask(cpu, frozen_cpus) {
+       for_each_cpu_mask_nr(cpu, frozen_cpus) {
                error = _cpu_up(cpu, 1);
                if (!error) {
                        printk("CPU%d is up\n", cpu);
@@ -427,3 +461,28 @@ out:
 #endif /* CONFIG_PM_SLEEP_SMP */
 
 #endif /* CONFIG_SMP */
+
+/*
+ * cpu_bit_bitmap[] is a special, "compressed" data structure that
+ * represents all NR_CPUS bits binary values of 1<<nr.
+ *
+ * It is used by cpumask_of_cpu() to get a constant address to a CPU
+ * mask value that has a single bit set only.
+ */
+
+/* cpu_bit_bitmap[0] is empty - so we can back into it */
+#define MASK_DECLARE_1(x)      [x+1][0] = 1UL << (x)
+#define MASK_DECLARE_2(x)      MASK_DECLARE_1(x), MASK_DECLARE_1(x+1)
+#define MASK_DECLARE_4(x)      MASK_DECLARE_2(x), MASK_DECLARE_2(x+2)
+#define MASK_DECLARE_8(x)      MASK_DECLARE_4(x), MASK_DECLARE_4(x+4)
+
+const unsigned long cpu_bit_bitmap[BITS_PER_LONG+1][BITS_TO_LONGS(NR_CPUS)] = {
+
+       MASK_DECLARE_8(0),      MASK_DECLARE_8(8),
+       MASK_DECLARE_8(16),     MASK_DECLARE_8(24),
+#if BITS_PER_LONG > 32
+       MASK_DECLARE_8(32),     MASK_DECLARE_8(40),
+       MASK_DECLARE_8(48),     MASK_DECLARE_8(56),
+#endif
+};
+EXPORT_SYMBOL_GPL(cpu_bit_bitmap);