sparseirq: fix Alpha build failure

Impact: build fix on Alpha

-tip testing found this build failure on the Alpha defconfig:

/home/mingo/tip/fs/proc/stat.c: In function 'show_stat':
/home/mingo/tip/fs/proc/stat.c:48: error: implicit declaration of function 'for_each_irq_desc'
/home/mingo/tip/fs/proc/stat.c:48: error: expected ';' before '{' token

can not use irq_desc() in stat.c on older architectures.
Signed-off-by: Yinghai Lu <yinghai@kernel.orgg>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

fs/proc/stat.c

@@ -45,9 +45,12 @@ static int show_stat(struct seq_file *p, void *v)
 		softirq = cputime64_add(softirq, kstat_cpu(i).cpustat.softirq);
 		steal = cputime64_add(steal, kstat_cpu(i).cpustat.steal);
 		guest = cputime64_add(guest, kstat_cpu(i).cpustat.guest);
-		for_each_irq_desc(j, desc) {
+		for_each_irq_nr(j) {
+#ifdef CONFIG_SPARSE_IRQ
+			desc = irq_to_desc(j);
 			if (!desc)
 				continue;
+#endif
 			sum += kstat_irqs_cpu(j, i);
 		}
 		sum += arch_irq_stat_cpu(i);
@@ -92,14 +95,17 @@ static int show_stat(struct seq_file *p, void *v)
 	seq_printf(p, "intr %llu", (unsigned long long)sum);
 
 	/* sum again ? it could be updated? */
-	for (j = 0; j < NR_IRQS; j++) {
-		desc = irq_to_desc(j);
+	for_each_irq_nr(j) {
 		per_irq_sum = 0;
-
-		if (desc) {
-			for_each_possible_cpu(i)
-				per_irq_sum += kstat_irqs_cpu(j, i);
+#ifdef CONFIG_SPARSE_IRQ
+		desc = irq_to_desc(j);
+		if (!desc) {
+			seq_printf(p, " %u", per_irq_sum);
+			continue;
 		}
+#endif
+		for_each_possible_cpu(i)
+			per_irq_sum += kstat_irqs_cpu(j, i);
 
 		seq_printf(p, " %u", per_irq_sum);
 	}

include/linux/irq.h

@@ -198,7 +198,6 @@ extern void arch_init_copy_chip_data(struct irq_desc *old_desc,
 extern void arch_free_chip_data(struct irq_desc *old_desc, struct irq_desc *desc);
 
 #ifndef CONFIG_SPARSE_IRQ
-
 extern struct irq_desc irq_desc[NR_IRQS];
 
 static inline struct irq_desc *irq_to_desc(unsigned int irq)
@@ -210,14 +209,6 @@ static inline struct irq_desc *irq_to_desc_alloc_cpu(unsigned int irq, int cpu)
 	return irq_to_desc(irq);
 }
 
-#ifdef CONFIG_GENERIC_HARDIRQS
-# define for_each_irq_desc(irq, desc)		\
-	for (irq = 0, desc = irq_desc; irq < nr_irqs; irq++, desc++)
-# define for_each_irq_desc_reverse(irq, desc)                          \
-	for (irq = nr_irqs - 1, desc = irq_desc + (nr_irqs - 1);        \
-	    irq >= 0; irq--, desc--)
-#endif
-
 #else
 
 extern struct irq_desc *irq_to_desc(unsigned int irq);

include/linux/irqnr.h

@@ -8,9 +8,22 @@
 # define for_each_irq_desc(irq, desc)		\
 	for (irq = 0; irq < nr_irqs; irq++)
 
-static inline early_sparse_irq_init(void)
-{
-}
+# define for_each_irq_desc_reverse(irq, desc)                          \
+	for (irq = nr_irqs - 1; irq >= 0; irq--)
+#else
+#ifndef CONFIG_SPARSE_IRQ
+
+struct irq_desc;
+extern int nr_irqs;
+# define for_each_irq_desc(irq, desc)		\
+	for (irq = 0, desc = irq_desc; irq < nr_irqs; irq++, desc++)
+# define for_each_irq_desc_reverse(irq, desc)                          \
+	for (irq = nr_irqs - 1, desc = irq_desc + (nr_irqs - 1);        \
+	    irq >= 0; irq--, desc--)
 #endif
+#endif
+
+#define for_each_irq_nr(irq)                   \
+       for (irq = 0; irq < nr_irqs; irq++)
 
 #endif