x86: move kstat_irqs from kstat to irq_desc

based on Eric's patch ...

together mold it with dyn_array for irq_desc, will allcate kstat_irqs for
nr_irq_desc alltogether if needed. -- at that point nr_cpus is known already.

v2: make sure system without generic_hardirqs works they don't have irq_desc
v3: fix merging
v4: [mingo@elte.hu] fix typo

[ mingo@elte.hu ] irq: build fix

fix:

 arch/x86/xen/spinlock.c: In function 'xen_spin_lock_slow':
 arch/x86/xen/spinlock.c:90: error: 'struct kernel_stat' has no member named 'irqs'

Signed-off-by: Yinghai Lu <yhlu.kernel@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/include/linux/kernel_stat.h b/include/linux/kernel_stat.h
index fe1f7fe..f106167 100644
--- a/include/linux/kernel_stat.h
+++ b/include/linux/kernel_stat.h
@@ -28,10 +28,8 @@
 
 struct kernel_stat {
 	struct cpu_usage_stat	cpustat;
-#ifdef CONFIG_HAVE_DYN_ARRAY
-	unsigned int *irqs;
-#else
-	unsigned int irqs[NR_IRQS];
+#ifndef CONFIG_GENERIC_HARDIRQS
+       unsigned int irqs[NR_IRQS];
 #endif
 };
 
@@ -43,15 +41,25 @@
 
 extern unsigned long long nr_context_switches(void);
 
+#ifndef CONFIG_GENERIC_HARDIRQS
+static inline unsigned int kstat_irqs_cpu(unsigned int irq, int cpu)
+{
+       return kstat_cpu(cpu).irqs[irq];
+}
+#else
+extern unsigned int kstat_irqs_cpu(unsigned int irq, int cpu);
+#endif
+
 /*
  * Number of interrupts per specific IRQ source, since bootup
  */
-static inline int kstat_irqs(int irq)
+static inline unsigned int kstat_irqs(unsigned int irq)
 {
-	int cpu, sum = 0;
+	unsigned int sum = 0;
+	int cpu;
 
 	for_each_possible_cpu(cpu)
-		sum += kstat_cpu(cpu).irqs[irq];
+		sum += kstat_irqs_cpu(irq, cpu);
 
 	return sum;
 }