patch-2.1.31 linux/include/asm-alpha/spinlock.h

• Lines: 93
• Date: Fri Mar 28 11:13:21 1997
• Orig file: v2.1.30/linux/include/asm-alpha/spinlock.h
• Orig date: Wed Dec 31 16:00:00 1969

diff -u --recursive --new-file v2.1.30/linux/include/asm-alpha/spinlock.h linux/include/asm-alpha/spinlock.h
@@ -0,0 +1,92 @@
+#ifndef _ALPHA_SPINLOCK_H
+#define _ALPHA_SPINLOCK_H
+
+#ifndef __SMP__
+
+typedef struct { } spinlock_t;
+#define SPIN_LOCK_UNLOCKED { }
+
+#define spin_lock_init(lock)			do { } while(0)
+#define spin_lock(lock)				do { } while(0)
+#define spin_trylock(lock)			do { } while(0)
+#define spin_unlock(lock)			do { } while(0)
+#define spin_lock_irq(lock)			setipl(7)
+#define spin_unlock_irq(lock)			setipl(0)
+
+#define spin_lock_irqsave(lock, flags)		swpipl(flags,7)
+#define spin_unlock_irqrestore(lock, flags)	setipl(flags)
+
+#else
+
+/* Simple spin lock operations.  There are two variants, one clears IRQ's
+ * on the local processor, one does not.
+ *
+ * We make no fairness assumptions. They have a cost.
+ */
+
+typedef struct {
+	volatile unsigned long lock;
+	unsigned long previous;
+} spinlock_t;
+
+#define SPIN_LOCK_UNLOCKED { 0, 0 }
+
+typedef struct { unsigned long a[100]; } __dummy_lock_t;
+#define __dummy_lock(lock) (*(__dummy_lock_t *)(lock))
+
+#define spin_unlock(lock)				\
+	__asm__ __volatile__(				\
+	"mb; stq $31,%0"				\
+	:"=m" (__dummy_lock(lock)))
+
+static inline void spin_lock(spinlock_t * lock)
+{
+	__label__ l1;
+	long tmp;
+	long stuck = 0x100000000;
+l1:
+	/* Use sub-sections to put the actual loop at the end
+	   of this object file's text section so as to perfect
+	   branch prediction.  */
+	__asm__ __volatile__(
+	"1:	ldq_l	%0,%1\n"
+	"	subq	%2,1,%2\n"
+	"	blbs	%0,2f\n"
+	"	or	%0,1,%0\n"
+	"	stq_c	%0,%1\n"
+	"	beq	%0,3f\n"
+	"4:	mb\n"
+	".text 2\n"
+	"2:	ldq	%0,%1\n"
+	"	subq	%2,1,%2\n"
+	"3:	blt	%2,4b\n"
+	"	blbs	%0,2b\n"
+	"	br	1b\n"
+	".text"
+	: "=r" (tmp),
+	  "=m" (__dummy_lock(lock)),
+	  "=r" (stuck)
+	: "2" (stuck));
+
+	if (stuck < 0)
+		printk("spinlock stuck at %p (%lx)\n",&&l1,lock->previous);
+	else
+		lock->previous = (unsigned long) &&l1;
+}
+
+#define spin_trylock(lock) (!set_bit(0,(lock)))
+
+#define spin_lock_irq(lock) \
+	do { __cli(); spin_lock(lock); } while (0)
+
+#define spin_unlock_irq(lock) \
+	do { spin_unlock(lock); __sti(); } while (0)
+
+#define spin_lock_irqsave(lock, flags) \
+	do { swpipl(flags,7); spin_lock(lock); } while (0)
+
+#define spin_unlock_irqrestore(lock, flags) \
+	do { spin_unlock(lock); setipl(flags); } while (0)
+
+#endif /* SMP */
+#endif /* _ALPHA_SPINLOCK_H */