patch-2.2.4 linux/include/asm-ppc/semaphore-helper.h

• Lines: 108
• Date: Wed Mar 10 21:30:32 1999
• Orig file: v2.2.3/linux/include/asm-ppc/semaphore-helper.h
• Orig date: Wed Dec 31 16:00:00 1969

diff -u --recursive --new-file v2.2.3/linux/include/asm-ppc/semaphore-helper.h linux/include/asm-ppc/semaphore-helper.h
@@ -0,0 +1,107 @@
+#ifndef _PPC_SEMAPHORE_HELPER_H
+#define _PPC_SEMAPHORE_HELPER_H
+
+/*
+ * SMP- and interrupt-safe semaphores..
+ *
+ * (C) Copyright 1996 Linus Torvalds
+ * Adapted for PowerPC by Gary Thomas and Paul Mackerras
+ */
+
+#include <asm/atomic.h>
+
+/*
+ * These two (wake_one_more and waking_non_zero) _must_ execute
+ * atomically wrt each other.
+ *
+ * This is trivially done with load with reservation and
+ * store conditional on the ppc.
+ */
+
+static inline void wake_one_more(struct semaphore * sem)
+{
+	atomic_inc(&sem->waking);
+}
+
+static inline int waking_non_zero(struct semaphore *sem)
+{
+	int ret, tmp;
+
+	/* Atomic decrement sem->waking iff it is > 0 */
+	__asm__ __volatile__(
+		"1:	lwarx %1,0,%2\n"	/* tmp = sem->waking */
+		"	cmpwi 0,%1,0\n"		/* test tmp */
+		"	addic %1,%1,-1\n"	/* --tmp */
+		"	ble- 2f\n"		/* exit if tmp was <= 0 */
+		"	stwcx. %1,0,%2\n"	/* update sem->waking */
+		"	bne- 1b\n"		/* try again if update failed*/
+		"	li %0,1\n"		/* ret = 1 */
+		"2:"
+		: "=r" (ret), "=&r" (tmp)
+		: "r" (&sem->waking), "0" (0)
+		: "cr0", "memory");
+
+	return ret;
+}
+/*
+ * waking_non_zero_interruptible:
+ *	1	got the lock
+ *	0	go to sleep
+ *	-EINTR	interrupted
+ */
+static inline int waking_non_zero_interruptible(struct semaphore *sem,
+						struct task_struct *tsk)
+{
+	int ret, tmp;
+
+	/* Atomic decrement sem->waking iff it is > 0 */
+	__asm__ __volatile__(
+		"1:	lwarx %1,0,%2\n"	/* tmp = sem->waking */
+		"	cmpwi 0,%1,0\n"		/* test tmp */
+		"	addic %1,%1,-1\n"	/* --tmp */
+		"	ble- 2f\n"		/* exit if tmp was <= 0 */
+		"	stwcx. %1,0,%2\n"	/* update sem->waking */
+		"	bne- 1b\n"		/* try again if update failed*/
+		"	li %0,1\n"		/* ret = 1 */
+		"2:"
+		: "=r" (ret), "=&r" (tmp)
+		: "r" (&sem->waking), "0" (0)
+		: "cr0", "memory");
+
+	if (ret == 0 && signal_pending(tsk)) {
+		atomic_inc(&sem->count);
+		ret = -EINTR;
+	}
+	return ret;
+}
+
+/*
+ * waking_non_zero_trylock:
+ *	1	failed to lock
+ *	0	got the lock
+ */
+static inline int waking_non_zero_trylock(struct semaphore *sem)
+{
+	int ret, tmp;
+
+	/* Atomic decrement sem->waking iff it is > 0 */
+	__asm__ __volatile__(
+		"1:	lwarx %1,0,%2\n"	/* tmp = sem->waking */
+		"	cmpwi 0,%1,0\n"		/* test tmp */
+		"	addic %1,%1,-1\n"	/* --tmp */
+		"	ble- 2f\n"		/* exit if tmp was <= 0 */
+		"	stwcx. %1,0,%2\n"	/* update sem->waking */
+		"	bne- 1b\n"		/* try again if update failed*/
+		"	li %0,0\n"		/* ret = 0 */
+		"2:"
+		: "=r" (ret), "=&r" (tmp)
+		: "r" (&sem->waking), "0" (1)
+		: "cr0", "memory");
+
+	if (ret)
+		atomic_inc(&sem->count);
+
+	return ret;
+}
+
+#endif /* _PPC_SEMAPHORE_HELPER_H */