1 files changed, 115 insertions, 0 deletions

diff --git a/include/linux/rwsem.h b/include/linux/rwsem.h
new file mode 100644
index 000000000000..bfb988885002
--- /dev/null
+++ b/include/linux/rwsem.h
@@ -0,0 +1,115 @@
+/* rwsem.h: R/W semaphores, public interface
+ *
+ * Written by David Howells (dhowells@redhat.com).
+ * Derived from asm-i386/semaphore.h
+ */
+
+#ifndef _LINUX_RWSEM_H
+#define _LINUX_RWSEM_H
+
+#include <linux/linkage.h>
+
+#define RWSEM_DEBUG 0
+
+#ifdef __KERNEL__
+
+#include <linux/config.h>
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <asm/system.h>
+#include <asm/atomic.h>
+
+struct rw_semaphore;
+
+#ifdef CONFIG_RWSEM_GENERIC_SPINLOCK
+#include <linux/rwsem-spinlock.h> /* use a generic implementation */
+#else
+#include <asm/rwsem.h> /* use an arch-specific implementation */
+#endif
+
+#ifndef rwsemtrace
+#if RWSEM_DEBUG
+extern void FASTCALL(rwsemtrace(struct rw_semaphore *sem, const char *str));
+#else
+#define rwsemtrace(SEM,FMT)
+#endif
+#endif
+
+/*
+ * lock for reading
+ */
+static inline void down_read(struct rw_semaphore *sem)
+{
+        might_sleep();
+        rwsemtrace(sem,"Entering down_read");
+        __down_read(sem);
+        rwsemtrace(sem,"Leaving down_read");
+}
+
+/*
+ * trylock for reading -- returns 1 if successful, 0 if contention
+ */
+static inline int down_read_trylock(struct rw_semaphore *sem)
+{
+        int ret;
+        rwsemtrace(sem,"Entering down_read_trylock");
+        ret = __down_read_trylock(sem);
+        rwsemtrace(sem,"Leaving down_read_trylock");
+        return ret;
+}
+
+/*
+ * lock for writing
+ */
+static inline void down_write(struct rw_semaphore *sem)
+{
+        might_sleep();
+        rwsemtrace(sem,"Entering down_write");
+        __down_write(sem);
+        rwsemtrace(sem,"Leaving down_write");
+}
+
+/*
+ * trylock for writing -- returns 1 if successful, 0 if contention
+ */
+static inline int down_write_trylock(struct rw_semaphore *sem)
+{
+        int ret;
+        rwsemtrace(sem,"Entering down_write_trylock");
+        ret = __down_write_trylock(sem);
+        rwsemtrace(sem,"Leaving down_write_trylock");
+        return ret;
+}
+
+/*
+ * release a read lock
+ */
+static inline void up_read(struct rw_semaphore *sem)
+{
+        rwsemtrace(sem,"Entering up_read");
+        __up_read(sem);
+        rwsemtrace(sem,"Leaving up_read");
+}
+
+/*
+ * release a write lock
+ */
+static inline void up_write(struct rw_semaphore *sem)
+{
+        rwsemtrace(sem,"Entering up_write");
+        __up_write(sem);
+        rwsemtrace(sem,"Leaving up_write");
+}
+
+/*
+ * downgrade write lock to read lock
+ */
+static inline void downgrade_write(struct rw_semaphore *sem)
+{
+        rwsemtrace(sem,"Entering downgrade_write");
+        __downgrade_write(sem);
+        rwsemtrace(sem,"Leaving downgrade_write");
+}
+
+#endif /* __KERNEL__ */
+#endif /* _LINUX_RWSEM_H */