Linux-2.6.12-rc2
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.
Let it rip!
diff --git a/include/linux/percpu_counter.h b/include/linux/percpu_counter.h
new file mode 100644
index 0000000..bd6708e
--- /dev/null
+++ b/include/linux/percpu_counter.h
@@ -0,0 +1,107 @@
+#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/config.h>
+#include <linux/spinlock.h>
+#include <linux/smp.h>
+#include <linux/threads.h>
+#include <linux/percpu.h>
+
+#ifdef CONFIG_SMP
+
+struct percpu_counter {
+ spinlock_t lock;
+ long count;
+ long *counters;
+};
+
+#if NR_CPUS >= 16
+#define FBC_BATCH (NR_CPUS*2)
+#else
+#define FBC_BATCH (NR_CPUS*4)
+#endif
+
+static inline void percpu_counter_init(struct percpu_counter *fbc)
+{
+ spin_lock_init(&fbc->lock);
+ fbc->count = 0;
+ fbc->counters = alloc_percpu(long);
+}
+
+static inline void percpu_counter_destroy(struct percpu_counter *fbc)
+{
+ free_percpu(fbc->counters);
+}
+
+void percpu_counter_mod(struct percpu_counter *fbc, long amount);
+
+static inline long 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 long percpu_counter_read_positive(struct percpu_counter *fbc)
+{
+ long ret = fbc->count;
+
+ barrier(); /* Prevent reloads of fbc->count */
+ if (ret > 0)
+ return ret;
+ return 1;
+}
+
+#else
+
+struct percpu_counter {
+ long count;
+};
+
+static inline void percpu_counter_init(struct percpu_counter *fbc)
+{
+ fbc->count = 0;
+}
+
+static inline void percpu_counter_destroy(struct percpu_counter *fbc)
+{
+}
+
+static inline void
+percpu_counter_mod(struct percpu_counter *fbc, long amount)
+{
+ preempt_disable();
+ fbc->count += amount;
+ preempt_enable();
+}
+
+static inline long percpu_counter_read(struct percpu_counter *fbc)
+{
+ return fbc->count;
+}
+
+static inline long percpu_counter_read_positive(struct percpu_counter *fbc)
+{
+ return fbc->count;
+}
+
+#endif /* CONFIG_SMP */
+
+static inline void percpu_counter_inc(struct percpu_counter *fbc)
+{
+ percpu_counter_mod(fbc, 1);
+}
+
+static inline void percpu_counter_dec(struct percpu_counter *fbc)
+{
+ percpu_counter_mod(fbc, -1);
+}
+
+#endif /* _LINUX_PERCPU_COUNTER_H */