patch-2.3.48 linux/include/asm-mips64/semaphore-helper.h

• Lines: 150
• Date: Thu Feb 24 22:53:35 2000
• Orig file: v2.3.47/linux/include/asm-mips64/semaphore-helper.h
• Orig date: Wed Dec 31 16:00:00 1969

diff -u --recursive --new-file v2.3.47/linux/include/asm-mips64/semaphore-helper.h linux/include/asm-mips64/semaphore-helper.h
@@ -0,0 +1,149 @@
+/* $Id: semaphore-helper.h,v 1.3 1999/12/04 03:59:12 ralf Exp $
+ *
+ * SMP- and interrupt-safe semaphores helper functions.
+ *
+ * (C) Copyright 1996 Linus Torvalds
+ * (C) Copyright 1999 Andrea Arcangeli
+ * (C) Copyright 1999 Ralf Baechle
+ * (C) Copyright 1999 Silicon Graphics, Inc.
+ */
+#ifndef _ASM_SEMAPHORE_HELPER_H
+#define _ASM_SEMAPHORE_HELPER_H
+
+/*
+ * These two _must_ execute atomically wrt each other.
+ */
+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;
+
+	__asm__ __volatile__(
+	"1:\tll\t%1, %2\n\t"
+	"blez\t%1, 2f\n\t"
+	"subu\t%0, %1, 1\n\t"
+	"sc\t%0, %2\n\t"
+	"beqz\t%0, 1b\n\t"
+	"2:"
+	".text"
+	: "=r"(ret), "=r"(tmp), "=m"(__atomic_fool_gcc(&sem->waking))
+	: "0"(0));
+
+	return ret;
+}
+
+/*
+ * waking_non_zero_interruptible:
+ *	1	got the lock
+ *	0	go to sleep
+ *	-EINTR	interrupted
+ *
+ * We must undo the sem->count down_interruptible decrement
+ * simultaneously and atomicly with the sem->waking adjustment,
+ * otherwise we can race with wake_one_more.
+ *
+ * This is accomplished by doing a 64-bit ll/sc on the 2 32-bit words.
+ *
+ * Pseudocode:
+ *
+ * If(sem->waking > 0) {
+ *	Decrement(sem->waking)
+ *	Return(SUCCESS)
+ * } else If(segnal_pending(tsk)) {
+ *	Increment(sem->count)
+ *	Return(-EINTR)
+ * } else {
+ *	Return(SLEEP)
+ * }
+ */
+
+static inline int
+waking_non_zero_interruptible(struct semaphore *sem, struct task_struct *tsk)
+{
+	long ret, tmp;
+
+#ifdef __MIPSEB__
+
+        __asm__ __volatile__("
+	.set	push
+	.set	noat
+0:	lld	%1, %2
+	li	%0, 0
+	sll	$1, %1, 0
+	blez	$1, 1f
+	daddiu	%1, %1, -1
+	li	%0, 1
+	b 	2f
+1:
+	beqz	%3, 2f
+	li	%0, %4
+	dli	$1, 0x0000000100000000
+	daddu	%1, %1, $1
+2:
+	scd	%1, %2
+	beqz	%1, 0b
+	.set	pop"
+	: "=&r"(ret), "=&r"(tmp), "=m"(*sem)
+	: "r"(signal_pending(tsk)), "i"(-EINTR));
+
+#elif defined(__MIPSEL__)
+
+	__asm__ __volatile__("
+	.set	push
+	.set	noat
+0:
+	lld	%1, %2
+	li	%0, 0
+	blez	%1, 1f
+	dli	$1, 0x0000000100000000
+	dsubu	%1, %1, $1
+	li	%0, 1
+	b	2f
+1:
+	beqz	%3, 2f
+	li	%0, %4
+	/* 
+	 * It would be nice to assume that sem->count
+	 * is != -1, but we will guard against that case
+	 */
+	daddiu	$1, %1, 1
+	dsll32	$1, $1, 0
+	dsrl32	$1, $1, 0
+	dsrl32	%1, %1, 0
+	dsll32	%1, %1, 0
+	or	%1, %1, $1
+2:
+	scd	%1, %2
+	beqz	%1, 0b
+	.set	pop"
+	: "=&r"(ret), "=&r"(tmp), "=m"(*sem)
+	: "r"(signal_pending(tsk)), "i"(-EINTR));
+
+#else
+#error "MIPS but neither __MIPSEL__ nor __MIPSEB__?"
+#endif
+
+	return ret;
+}
+
+/*
+ * waking_non_zero_trylock is unused.  we do everything in 
+ * down_trylock and let non-ll/sc hosts bounce around.
+ */
+
+static inline int
+waking_non_zero_trylock(struct semaphore *sem)
+{
+#if WAITQUEUE_DEBUG
+	CHECK_MAGIC(sem->__magic);
+#endif
+
+	return 0;
+}
+
+#endif /* _ASM_SEMAPHORE_HELPER_H */