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diff --git a/src/include/qemu/rfifolock.h b/src/include/qemu/rfifolock.h
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+/*
+ * Recursive FIFO lock
+ *
+ * Copyright Red Hat, Inc. 2013
+ *
+ * Authors:
+ * Stefan Hajnoczi <stefanha@redhat.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ *
+ */
+
+#ifndef QEMU_RFIFOLOCK_H
+#define QEMU_RFIFOLOCK_H
+
+#include "qemu/thread.h"
+
+/* Recursive FIFO lock
+ *
+ * This lock provides more features than a plain mutex:
+ *
+ * 1. Fairness - enforces FIFO order.
+ * 2. Nesting - can be taken recursively.
+ * 3. Contention callback - optional, called when thread must wait.
+ *
+ * The recursive FIFO lock is heavyweight so prefer other synchronization
+ * primitives if you do not need its features.
+ */
+typedef struct {
+ QemuMutex lock; /* protects all fields */
+
+ /* FIFO order */
+ unsigned int head; /* active ticket number */
+ unsigned int tail; /* waiting ticket number */
+ QemuCond cond; /* used to wait for our ticket number */
+
+ /* Nesting */
+ QemuThread owner_thread; /* thread that currently has ownership */
+ unsigned int nesting; /* amount of nesting levels */
+
+ /* Contention callback */
+ void (*cb)(void *); /* called when thread must wait, with ->lock
+ * held so it may not recursively lock/unlock
+ */
+ void *cb_opaque;
+} RFifoLock;
+
+void rfifolock_init(RFifoLock *r, void (*cb)(void *), void *opaque);
+void rfifolock_destroy(RFifoLock *r);
+void rfifolock_lock(RFifoLock *r);
+void rfifolock_unlock(RFifoLock *r);
+
+#endif /* QEMU_RFIFOLOCK_H */
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