patch-2.3.9 linux/include/asm-mips/semaphore-helper.h

• Lines: 126
• Date: Fri Jun 25 17:37:53 1999
• Orig file: v2.3.8/linux/include/asm-mips/semaphore-helper.h
• Orig date: Wed Dec 31 16:00:00 1969

diff -u --recursive --new-file v2.3.8/linux/include/asm-mips/semaphore-helper.h linux/include/asm-mips/semaphore-helper.h
@@ -0,0 +1,125 @@
+/* $Id: semaphore-helper.h,v 1.3 1999/06/11 14:30:15 ralf Exp $
+ *
+ * SMP- and interrupt-safe semaphores helper functions.
+ *
+ * (C) Copyright 1996 Linus Torvalds
+ * (C) Copyright 1999 Andrea Arcangeli
+ * (C) Copyright 1999 Ralf Baechle
+ */
+#ifndef __ASM_MIPS_SEMAPHORE_HELPER_H
+#define __ASM_MIPS_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.
+ *
+ * This is crazy.  Normally it stricly forbidden to use 64-bit operation
+ * in the 32-bit MIPS kernel.  In this case it's however ok because if an
+ * interrupt has destroyed the upper half of registers sc will fail.
+ */
+static inline int
+waking_non_zero_interruptible(struct semaphore *sem, struct task_struct *tsk)
+{
+	long ret, tmp;
+
+#ifdef __MIPSEB__
+        __asm__ __volatile__("
+	.set	mips3
+	.set	push
+	.set	noat
+0:	lld	%1,%2
+	li	%0,0
+
+	bltz	%1, 1f
+	dli	$1, 0xffffffff00000000
+	daddu	%1, $1
+	li	%0, 1
+	b	2f
+1:
+
+	beqz	%3, 1f
+	addiu	$1, %1, 1
+	dsll32	$1, $1, 0
+	dsrl32	$1, $1, 0
+	dsrl32	%1, %1, 0
+	dsll32	%1, %1, 0
+	or	%1, $1
+	li	%0, %4
+	b	2f
+1:
+	scd	%1, %2
+2:
+	beqz	%1,0b
+	.set	pop
+	.set	mips0"
+	: "=&r"(ret), "=&r"(tmp), "=m"(*sem)
+	: "r"(signal_pending(tsk)), "i"(-EINTR));
+#endif
+
+#ifdef __MIPSEL__
+#error "FIXME: waking_non_zero_interruptible doesn't support little endian machines yet."
+#endif
+
+	return ret;
+}
+
+/*
+ * waking_non_zero_trylock:
+ *	1	failed to lock
+ *	0	got the lock
+ *
+ * XXX SMP ALERT
+ */
+#ifdef __SMP__
+#error FIXME, waking_non_zero_trylock is broken for SMP.
+#endif
+static inline int waking_non_zero_trylock(struct semaphore *sem)
+{
+        int ret = 1;
+
+	if (atomic_read(&sem->waking) <= 0)
+		atomic_inc(&sem->count);
+	else {
+		atomic_dec(&sem->waking);
+		ret = 0;
+	}
+
+	return ret;
+}
+
+#endif /* __ASM_MIPS_SEMAPHORE_HELPER_H */