parisc: Improve interrupt handling in arch_spin_lock_flags()

Rewrite arch_spin_lock() and arch_spin_lock_flags() to not re-enable and
disable the PSW_SM_I interrupt flag too often.
Signed-off-by: Helge Deller <deller@gmx.de>

arch/parisc/include/asm/spinlock.h

@@ -10,25 +10,34 @@
 static inline int arch_spin_is_locked(arch_spinlock_t *x)
 {
 	volatile unsigned int *a = __ldcw_align(x);
+	smp_mb();
 	return *a == 0;
 }
 
-#define arch_spin_lock(lock) arch_spin_lock_flags(lock, 0)
+static inline void arch_spin_lock(arch_spinlock_t *x)
+{
+	volatile unsigned int *a;
+
+	a = __ldcw_align(x);
+	while (__ldcw(a) == 0)
+		while (*a == 0)
+			cpu_relax();
+}
 
 static inline void arch_spin_lock_flags(arch_spinlock_t *x,
 					 unsigned long flags)
 {
 	volatile unsigned int *a;
+	unsigned long flags_dis;
 
 	a = __ldcw_align(x);
-	while (__ldcw(a) == 0)
+	while (__ldcw(a) == 0) {
+		local_save_flags(flags_dis);
+		local_irq_restore(flags);
 		while (*a == 0)
-			if (flags & PSW_SM_I) {
-				local_irq_enable();
-				cpu_relax();
-				local_irq_disable();
-			} else
-				cpu_relax();
+			cpu_relax();
+		local_irq_restore(flags_dis);
+	}
 }
 #define arch_spin_lock_flags arch_spin_lock_flags