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authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
commit1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch)
tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /include/asm-s390/semaphore.h
Linux-2.6.12-rc2v2.6.12-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!
Diffstat (limited to 'include/asm-s390/semaphore.h')
-rw-r--r--include/asm-s390/semaphore.h110
1 files changed, 110 insertions, 0 deletions
diff --git a/include/asm-s390/semaphore.h b/include/asm-s390/semaphore.h
new file mode 100644
index 000000000000..873def6f363a
--- /dev/null
+++ b/include/asm-s390/semaphore.h
@@ -0,0 +1,110 @@
+/*
+ * include/asm-s390/semaphore.h
+ *
+ * S390 version
+ * Copyright (C) 1999 IBM Deutschland Entwicklung GmbH, IBM Corporation
+ *
+ * Derived from "include/asm-i386/semaphore.h"
+ * (C) Copyright 1996 Linus Torvalds
+ */
+
+#ifndef _S390_SEMAPHORE_H
+#define _S390_SEMAPHORE_H
+
+#include <asm/system.h>
+#include <asm/atomic.h>
+#include <linux/wait.h>
+#include <linux/rwsem.h>
+
+struct semaphore {
+ /*
+ * Note that any negative value of count is equivalent to 0,
+ * but additionally indicates that some process(es) might be
+ * sleeping on `wait'.
+ */
+ atomic_t count;
+ wait_queue_head_t wait;
+};
+
+#define __SEMAPHORE_INITIALIZER(name,count) \
+ { ATOMIC_INIT(count), __WAIT_QUEUE_HEAD_INITIALIZER((name).wait) }
+
+#define __MUTEX_INITIALIZER(name) \
+ __SEMAPHORE_INITIALIZER(name,1)
+
+#define __DECLARE_SEMAPHORE_GENERIC(name,count) \
+ struct semaphore name = __SEMAPHORE_INITIALIZER(name,count)
+
+#define DECLARE_MUTEX(name) __DECLARE_SEMAPHORE_GENERIC(name,1)
+#define DECLARE_MUTEX_LOCKED(name) __DECLARE_SEMAPHORE_GENERIC(name,0)
+
+static inline void sema_init (struct semaphore *sem, int val)
+{
+ *sem = (struct semaphore) __SEMAPHORE_INITIALIZER((*sem),val);
+}
+
+static inline void init_MUTEX (struct semaphore *sem)
+{
+ sema_init(sem, 1);
+}
+
+static inline void init_MUTEX_LOCKED (struct semaphore *sem)
+{
+ sema_init(sem, 0);
+}
+
+asmlinkage void __down(struct semaphore * sem);
+asmlinkage int __down_interruptible(struct semaphore * sem);
+asmlinkage int __down_trylock(struct semaphore * sem);
+asmlinkage void __up(struct semaphore * sem);
+
+static inline void down(struct semaphore * sem)
+{
+ might_sleep();
+ if (atomic_dec_return(&sem->count) < 0)
+ __down(sem);
+}
+
+static inline int down_interruptible(struct semaphore * sem)
+{
+ int ret = 0;
+
+ might_sleep();
+ if (atomic_dec_return(&sem->count) < 0)
+ ret = __down_interruptible(sem);
+ return ret;
+}
+
+static inline int down_trylock(struct semaphore * sem)
+{
+ int old_val, new_val;
+
+ /*
+ * This inline assembly atomically implements the equivalent
+ * to the following C code:
+ * old_val = sem->count.counter;
+ * if ((new_val = old_val) > 0)
+ * sem->count.counter = --new_val;
+ * In the ppc code this is called atomic_dec_if_positive.
+ */
+ __asm__ __volatile__ (
+ " l %0,0(%3)\n"
+ "0: ltr %1,%0\n"
+ " jle 1f\n"
+ " ahi %1,-1\n"
+ " cs %0,%1,0(%3)\n"
+ " jl 0b\n"
+ "1:"
+ : "=&d" (old_val), "=&d" (new_val), "=m" (sem->count.counter)
+ : "a" (&sem->count.counter), "m" (sem->count.counter)
+ : "cc", "memory" );
+ return old_val <= 0;
+}
+
+static inline void up(struct semaphore * sem)
+{
+ if (atomic_inc_return(&sem->count) <= 0)
+ __up(sem);
+}
+
+#endif