1 files changed, 65 insertions, 0 deletions
diff --git a/lib/brlock.c b/lib/brlock.c
new file mode 100644
index 000000000..3c3577309
--- /dev/null
+++ b/lib/brlock.c
@@ -0,0 +1,65 @@
+/*
+ *
+ * linux/lib/brlock.c
+ *
+ * 'Big Reader' read-write spinlocks.  See linux/brlock.h for details.
+ *
+ * Copyright 2000, Ingo Molnar <mingo@redhat.com>
+ * Copyright 2000, David S. Miller <davem@redhat.com>
+ */
+
+#include <linux/config.h>
+
+#ifdef CONFIG_SMP
+
+#include <linux/sched.h>
+#include <linux/brlock.h>
+
+#ifdef __BRLOCK_USE_ATOMICS
+
+brlock_read_lock_t __brlock_array[NR_CPUS][__BR_IDX_MAX] =
+   { [0 ... NR_CPUS-1] = { [0 ... __BR_IDX_MAX-1] = RW_LOCK_UNLOCKED } };
+
+void __br_write_lock (enum brlock_indices idx)
+{
+	int i;
+
+	for (i = 0; i < smp_num_cpus; i++)
+		write_lock(__brlock_array[idx] + i);
+}
+
+void __br_write_unlock (enum brlock_indices idx)
+{
+	int i;
+
+	for (i = 0; i < smp_num_cpus; i++)
+		write_unlock(__brlock_array[idx] + i);
+}
+
+#else /* ! __BRLOCK_USE_ATOMICS */
+
+brlock_read_lock_t __brlock_array[NR_CPUS][__BR_IDX_MAX] =
+   { [0 ... NR_CPUS-1] = { [0 ... __BR_IDX_MAX-1] = 0 } };
+
+struct br_wrlock __br_write_locks[__BR_IDX_MAX] =
+   { [0 ... __BR_IDX_MAX-1] = { SPIN_LOCK_UNLOCKED } };
+
+void __br_write_lock (enum brlock_indices idx)
+{
+	int i;
+
+	spin_lock(&__br_write_locks[idx].lock);
+again:
+	for (i = 0; i < smp_num_cpus; i++)
+		if (__brlock_array[i][idx] != 0)
+			goto again;
+}
+
+void __br_write_unlock (enum brlock_indices idx)
+{
+	spin_unlock(&__br_write_locks[idx].lock);
+}
+
+#endif /* __BRLOCK_USE_ATOMICS */
+
+#endif /* CONFIG_SMP */