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-rw-r--r--include/linux/osq_lock.h19
1 files changed, 19 insertions, 0 deletions
diff --git a/include/linux/osq_lock.h b/include/linux/osq_lock.h
new file mode 100644
index 000000000000..b001682bf7cb
--- /dev/null
+++ b/include/linux/osq_lock.h
@@ -0,0 +1,19 @@
+#ifndef __LINUX_OSQ_LOCK_H
+#define __LINUX_OSQ_LOCK_H
+
+/*
+ * An MCS like lock especially tailored for optimistic spinning for sleeping
+ * lock implementations (mutex, rwsem, etc).
+ */
+
+#define OSQ_UNLOCKED_VAL (0)
+
+struct optimistic_spin_queue {
+ /*
+ * Stores an encoded value of the CPU # of the tail node in the queue.
+ * If the queue is empty, then it's set to OSQ_UNLOCKED_VAL.
+ */
+ atomic_t tail;
+};
+
+#endif