lib/percpu_counter.c: enclose hotplug only variables in hotplug ifdef
[linux-2.6.git] / lib / percpu_counter.c
index 8504490..f8a3f1a 100644 (file)
  */
 
 #include <linux/percpu_counter.h>
+#include <linux/notifier.h>
+#include <linux/mutex.h>
+#include <linux/init.h>
+#include <linux/cpu.h>
 #include <linux/module.h>
+#include <linux/debugobjects.h>
 
-void percpu_counter_mod(struct percpu_counter *fbc, s32 amount)
+#ifdef CONFIG_HOTPLUG_CPU
+static LIST_HEAD(percpu_counters);
+static DEFINE_MUTEX(percpu_counters_lock);
+#endif
+
+#ifdef CONFIG_DEBUG_OBJECTS_PERCPU_COUNTER
+
+static struct debug_obj_descr percpu_counter_debug_descr;
+
+static int percpu_counter_fixup_free(void *addr, enum debug_obj_state state)
 {
-       long count;
-       s32 *pcount;
-       int cpu = get_cpu();
+       struct percpu_counter *fbc = addr;
 
-       pcount = per_cpu_ptr(fbc->counters, cpu);
-       count = *pcount + amount;
-       if (count >= FBC_BATCH || count <= -FBC_BATCH) {
-               spin_lock(&fbc->lock);
-               fbc->count += count;
+       switch (state) {
+       case ODEBUG_STATE_ACTIVE:
+               percpu_counter_destroy(fbc);
+               debug_object_free(fbc, &percpu_counter_debug_descr);
+               return 1;
+       default:
+               return 0;
+       }
+}
+
+static struct debug_obj_descr percpu_counter_debug_descr = {
+       .name           = "percpu_counter",
+       .fixup_free     = percpu_counter_fixup_free,
+};
+
+static inline void debug_percpu_counter_activate(struct percpu_counter *fbc)
+{
+       debug_object_init(fbc, &percpu_counter_debug_descr);
+       debug_object_activate(fbc, &percpu_counter_debug_descr);
+}
+
+static inline void debug_percpu_counter_deactivate(struct percpu_counter *fbc)
+{
+       debug_object_deactivate(fbc, &percpu_counter_debug_descr);
+       debug_object_free(fbc, &percpu_counter_debug_descr);
+}
+
+#else  /* CONFIG_DEBUG_OBJECTS_PERCPU_COUNTER */
+static inline void debug_percpu_counter_activate(struct percpu_counter *fbc)
+{ }
+static inline void debug_percpu_counter_deactivate(struct percpu_counter *fbc)
+{ }
+#endif /* CONFIG_DEBUG_OBJECTS_PERCPU_COUNTER */
+
+void percpu_counter_set(struct percpu_counter *fbc, s64 amount)
+{
+       int cpu;
+
+       raw_spin_lock(&fbc->lock);
+       for_each_possible_cpu(cpu) {
+               s32 *pcount = per_cpu_ptr(fbc->counters, cpu);
                *pcount = 0;
-               spin_unlock(&fbc->lock);
+       }
+       fbc->count = amount;
+       raw_spin_unlock(&fbc->lock);
+}
+EXPORT_SYMBOL(percpu_counter_set);
+
+void __percpu_counter_add(struct percpu_counter *fbc, s64 amount, s32 batch)
+{
+       s64 count;
+
+       preempt_disable();
+       count = __this_cpu_read(*fbc->counters) + amount;
+       if (count >= batch || count <= -batch) {
+               raw_spin_lock(&fbc->lock);
+               fbc->count += count;
+               __this_cpu_write(*fbc->counters, 0);
+               raw_spin_unlock(&fbc->lock);
        } else {
-               *pcount = count;
+               __this_cpu_write(*fbc->counters, count);
        }
-       put_cpu();
+       preempt_enable();
 }
-EXPORT_SYMBOL(percpu_counter_mod);
+EXPORT_SYMBOL(__percpu_counter_add);
 
 /*
  * Add up all the per-cpu counts, return the result.  This is a more accurate
  * but much slower version of percpu_counter_read_positive()
  */
-s64 percpu_counter_sum(struct percpu_counter *fbc)
+s64 __percpu_counter_sum(struct percpu_counter *fbc)
 {
        s64 ret;
        int cpu;
 
-       spin_lock(&fbc->lock);
+       raw_spin_lock(&fbc->lock);
        ret = fbc->count;
-       for_each_possible_cpu(cpu) {
+       for_each_online_cpu(cpu) {
                s32 *pcount = per_cpu_ptr(fbc->counters, cpu);
                ret += *pcount;
        }
-       spin_unlock(&fbc->lock);
-       return ret < 0 ? 0 : ret;
+       raw_spin_unlock(&fbc->lock);
+       return ret;
+}
+EXPORT_SYMBOL(__percpu_counter_sum);
+
+int __percpu_counter_init(struct percpu_counter *fbc, s64 amount,
+                         struct lock_class_key *key)
+{
+       raw_spin_lock_init(&fbc->lock);
+       lockdep_set_class(&fbc->lock, key);
+       fbc->count = amount;
+       fbc->counters = alloc_percpu(s32);
+       if (!fbc->counters)
+               return -ENOMEM;
+
+       debug_percpu_counter_activate(fbc);
+
+#ifdef CONFIG_HOTPLUG_CPU
+       INIT_LIST_HEAD(&fbc->list);
+       mutex_lock(&percpu_counters_lock);
+       list_add(&fbc->list, &percpu_counters);
+       mutex_unlock(&percpu_counters_lock);
+#endif
+       return 0;
+}
+EXPORT_SYMBOL(__percpu_counter_init);
+
+void percpu_counter_destroy(struct percpu_counter *fbc)
+{
+       if (!fbc->counters)
+               return;
+
+       debug_percpu_counter_deactivate(fbc);
+
+#ifdef CONFIG_HOTPLUG_CPU
+       mutex_lock(&percpu_counters_lock);
+       list_del(&fbc->list);
+       mutex_unlock(&percpu_counters_lock);
+#endif
+       free_percpu(fbc->counters);
+       fbc->counters = NULL;
+}
+EXPORT_SYMBOL(percpu_counter_destroy);
+
+int percpu_counter_batch __read_mostly = 32;
+EXPORT_SYMBOL(percpu_counter_batch);
+
+static void compute_batch_value(void)
+{
+       int nr = num_online_cpus();
+
+       percpu_counter_batch = max(32, nr*2);
+}
+
+static int __cpuinit percpu_counter_hotcpu_callback(struct notifier_block *nb,
+                                       unsigned long action, void *hcpu)
+{
+#ifdef CONFIG_HOTPLUG_CPU
+       unsigned int cpu;
+       struct percpu_counter *fbc;
+
+       compute_batch_value();
+       if (action != CPU_DEAD)
+               return NOTIFY_OK;
+
+       cpu = (unsigned long)hcpu;
+       mutex_lock(&percpu_counters_lock);
+       list_for_each_entry(fbc, &percpu_counters, list) {
+               s32 *pcount;
+               unsigned long flags;
+
+               raw_spin_lock_irqsave(&fbc->lock, flags);
+               pcount = per_cpu_ptr(fbc->counters, cpu);
+               fbc->count += *pcount;
+               *pcount = 0;
+               raw_spin_unlock_irqrestore(&fbc->lock, flags);
+       }
+       mutex_unlock(&percpu_counters_lock);
+#endif
+       return NOTIFY_OK;
+}
+
+/*
+ * Compare counter against given value.
+ * Return 1 if greater, 0 if equal and -1 if less
+ */
+int percpu_counter_compare(struct percpu_counter *fbc, s64 rhs)
+{
+       s64     count;
+
+       count = percpu_counter_read(fbc);
+       /* Check to see if rough count will be sufficient for comparison */
+       if (abs(count - rhs) > (percpu_counter_batch*num_online_cpus())) {
+               if (count > rhs)
+                       return 1;
+               else
+                       return -1;
+       }
+       /* Need to use precise count */
+       count = percpu_counter_sum(fbc);
+       if (count > rhs)
+               return 1;
+       else if (count < rhs)
+               return -1;
+       else
+               return 0;
+}
+EXPORT_SYMBOL(percpu_counter_compare);
+
+static int __init percpu_counter_startup(void)
+{
+       compute_batch_value();
+       hotcpu_notifier(percpu_counter_hotcpu_callback, 0);
+       return 0;
 }
-EXPORT_SYMBOL(percpu_counter_sum);
+module_init(percpu_counter_startup);