irq: add irq_desc_without_new

add an irq_desc accessor that will not allocate any sparse entry
but returns failure if there's no entry present.

Signed-off-by: Yinghai Lu <yhlu.kernel@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

2 files changed, 37 insertions, 4 deletions

diff --git a/include/linux/irq.h b/include/linux/irq.h
index cbf471aee1ce..c9ffef7c3b44 100644
--- a/include/linux/irq.h
+++ b/include/linux/irq.h
@@ -191,10 +191,23 @@ struct irq_desc {
 } ____cacheline_internodealigned_in_smp;
 
 extern struct irq_desc *irq_to_desc(unsigned int irq);
+extern struct irq_desc *__irq_to_desc(unsigned int irq);
+
+#ifndef CONFIG_HAVE_SPARSE_IRQ
+
 #ifndef CONFIG_HAVE_DYN_ARRAY
 /* could be removed if we get rid of all irq_desc reference */
 extern struct irq_desc irq_desc[NR_IRQS];
+#else
+extern struct irq_desc *irq_desc;
 #endif
+
+#else
+
+extern struct irq_desc *sparse_irqs;
+
+#endif
+
 #define kstat_irqs_this_cpu(DESC) \
         ((DESC)->kstat_irqs[smp_processor_id()])
 
diff --git a/kernel/irq/handle.c b/kernel/irq/handle.c
index 1f346990f3f8..8e55dbe50afc 100644
--- a/kernel/irq/handle.c
+++ b/kernel/irq/handle.c
@@ -112,7 +112,6 @@ static void init_kstat_irqs(struct irq_desc *desc, int nr_desc, int nr)
         }
 }
 
-
 static void __init init_work(void *data)
 {
         struct dyn_array *da = data;
@@ -149,9 +148,27 @@ static int __init parse_nr_irq_desc(char *arg)
 
 early_param("nr_irq_desc", parse_nr_irq_desc);
 
-static struct irq_desc *sparse_irqs;
+struct irq_desc *sparse_irqs;
 DEFINE_DYN_ARRAY(sparse_irqs, sizeof(struct irq_desc), nr_irq_desc, PAGE_SIZE, init_work);
 
+struct irq_desc *__irq_to_desc(unsigned int irq)
+{
+        struct irq_desc *desc;
+
+        BUG_ON(irq == -1U);
+
+        desc = &sparse_irqs[0];
+        while (desc) {
+                if (desc->irq == irq)
+                        return desc;
+
+                if (desc->irq == -1U)
+                        return NULL;
+
+                desc = desc->next;
+        }
+        return NULL;
+}
 struct irq_desc *irq_to_desc(unsigned int irq)
 {
         struct irq_desc *desc, *desc_pri;
@@ -208,8 +225,7 @@ struct irq_desc *irq_to_desc(unsigned int irq)
         return desc;
 }
 #else
-
-static struct irq_desc *irq_desc;
+struct irq_desc *irq_desc;
 DEFINE_DYN_ARRAY(irq_desc, sizeof(struct irq_desc), nr_irqs, PAGE_SIZE, init_work);
 
 #endif
@@ -239,6 +255,10 @@ struct irq_desc *irq_to_desc(unsigned int irq)
 
         return NULL;
 }
+struct irq_desc *__irq_to_desc(unsigned int irq)
+{
+        return irq_to_desc(irq);
+}
 #endif
 
 /*