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-rw-r--r--include/linux/percpu_counter.h177
1 files changed, 177 insertions, 0 deletions
diff --git a/include/linux/percpu_counter.h b/include/linux/percpu_counter.h
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+++ b/include/linux/percpu_counter.h
@@ -0,0 +1,177 @@
+#ifndef _LINUX_PERCPU_COUNTER_H
+#define _LINUX_PERCPU_COUNTER_H
+/*
+ * A simple "approximate counter" for use in ext2 and ext3 superblocks.
+ *
+ * WARNING: these things are HUGE. 4 kbytes per counter on 32-way P4.
+ */
+
+#include <linux/spinlock.h>
+#include <linux/smp.h>
+#include <linux/list.h>
+#include <linux/threads.h>
+#include <linux/percpu.h>
+#include <linux/types.h>
+
+#ifdef CONFIG_SMP
+
+struct percpu_counter {
+ raw_spinlock_t lock;
+ s64 count;
+#ifdef CONFIG_HOTPLUG_CPU
+ struct list_head list; /* All percpu_counters are on a list */
+#endif
+ s32 __percpu *counters;
+};
+
+extern int percpu_counter_batch;
+
+int __percpu_counter_init(struct percpu_counter *fbc, s64 amount,
+ struct lock_class_key *key);
+
+#define percpu_counter_init(fbc, value) \
+ ({ \
+ static struct lock_class_key __key; \
+ \
+ __percpu_counter_init(fbc, value, &__key); \
+ })
+
+void percpu_counter_destroy(struct percpu_counter *fbc);
+void percpu_counter_set(struct percpu_counter *fbc, s64 amount);
+void __percpu_counter_add(struct percpu_counter *fbc, s64 amount, s32 batch);
+s64 __percpu_counter_sum(struct percpu_counter *fbc);
+int percpu_counter_compare(struct percpu_counter *fbc, s64 rhs);
+
+static inline void percpu_counter_add(struct percpu_counter *fbc, s64 amount)
+{
+ __percpu_counter_add(fbc, amount, percpu_counter_batch);
+}
+
+static inline s64 percpu_counter_sum_positive(struct percpu_counter *fbc)
+{
+ s64 ret = __percpu_counter_sum(fbc);
+ return ret < 0 ? 0 : ret;
+}
+
+static inline s64 percpu_counter_sum(struct percpu_counter *fbc)
+{
+ return __percpu_counter_sum(fbc);
+}
+
+static inline s64 percpu_counter_read(struct percpu_counter *fbc)
+{
+ return fbc->count;
+}
+
+/*
+ * It is possible for the percpu_counter_read() to return a small negative
+ * number for some counter which should never be negative.
+ *
+ */
+static inline s64 percpu_counter_read_positive(struct percpu_counter *fbc)
+{
+ s64 ret = fbc->count;
+
+ barrier(); /* Prevent reloads of fbc->count */
+ if (ret >= 0)
+ return ret;
+ return 0;
+}
+
+static inline int percpu_counter_initialized(struct percpu_counter *fbc)
+{
+ return (fbc->counters != NULL);
+}
+
+#else
+
+struct percpu_counter {
+ s64 count;
+};
+
+static inline int percpu_counter_init(struct percpu_counter *fbc, s64 amount)
+{
+ fbc->count = amount;
+ return 0;
+}
+
+static inline void percpu_counter_destroy(struct percpu_counter *fbc)
+{
+}
+
+static inline void percpu_counter_set(struct percpu_counter *fbc, s64 amount)
+{
+ fbc->count = amount;
+}
+
+static inline int percpu_counter_compare(struct percpu_counter *fbc, s64 rhs)
+{
+ if (fbc->count > rhs)
+ return 1;
+ else if (fbc->count < rhs)
+ return -1;
+ else
+ return 0;
+}
+
+static inline void
+percpu_counter_add(struct percpu_counter *fbc, s64 amount)
+{
+ preempt_disable();
+ fbc->count += amount;
+ preempt_enable();
+}
+
+static inline void
+__percpu_counter_add(struct percpu_counter *fbc, s64 amount, s32 batch)
+{
+ percpu_counter_add(fbc, amount);
+}
+
+static inline s64 percpu_counter_read(struct percpu_counter *fbc)
+{
+ return fbc->count;
+}
+
+/*
+ * percpu_counter is intended to track positive numbers. In the UP case the
+ * number should never be negative.
+ */
+static inline s64 percpu_counter_read_positive(struct percpu_counter *fbc)
+{
+ return fbc->count;
+}
+
+static inline s64 percpu_counter_sum_positive(struct percpu_counter *fbc)
+{
+ return percpu_counter_read_positive(fbc);
+}
+
+static inline s64 percpu_counter_sum(struct percpu_counter *fbc)
+{
+ return percpu_counter_read(fbc);
+}
+
+static inline int percpu_counter_initialized(struct percpu_counter *fbc)
+{
+ return 1;
+}
+
+#endif /* CONFIG_SMP */
+
+static inline void percpu_counter_inc(struct percpu_counter *fbc)
+{
+ percpu_counter_add(fbc, 1);
+}
+
+static inline void percpu_counter_dec(struct percpu_counter *fbc)
+{
+ percpu_counter_add(fbc, -1);
+}
+
+static inline void percpu_counter_sub(struct percpu_counter *fbc, s64 amount)
+{
+ percpu_counter_add(fbc, -amount);
+}
+
+#endif /* _LINUX_PERCPU_COUNTER_H */