genirq: Prepare proc for real sparse irq support

/proc/irq never removes any entries, but when irq descriptors can be
freed for real this is necessary. Otherwise we'd reference a freed
descriptor in /proc/irq/N

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Ingo Molnar <mingo@elte.hu>

kernel/irq/internals.h

@@ -32,10 +32,12 @@ void replace_irq_desc(unsigned int irq, struct irq_desc *desc);
 
 #ifdef CONFIG_PROC_FS
 extern void register_irq_proc(unsigned int irq, struct irq_desc *desc);
+extern void unregister_irq_proc(unsigned int irq, struct irq_desc *desc);
 extern void register_handler_proc(unsigned int irq, struct irqaction *action);
 extern void unregister_handler_proc(unsigned int irq, struct irqaction *action);
 #else
 static inline void register_irq_proc(unsigned int irq, struct irq_desc *desc) { }
+static inline void unregister_irq_proc(unsigned int irq, struct irq_desc *desc) { }
 static inline void register_handler_proc(unsigned int irq,
 					 struct irqaction *action) { }
 static inline void unregister_handler_proc(unsigned int irq,

kernel/irq/irqdesc.c

@@ -205,6 +205,8 @@ static void free_desc(unsigned int irq)
 	struct irq_desc *desc = irq_to_desc(irq);
 	unsigned long flags;
 
+	unregister_irq_proc(irq, desc);
+
 	raw_spin_lock_irqsave(&sparse_irq_lock, flags);
 	delete_irq_desc(irq);
 	raw_spin_unlock_irqrestore(&sparse_irq_lock, flags);

kernel/irq/proc.c

@@ -297,6 +297,24 @@ void register_irq_proc(unsigned int irq, struct irq_desc *desc)
 			 &irq_spurious_proc_fops, (void *)(long)irq);
 }
 
+void unregister_irq_proc(unsigned int irq, struct irq_desc *desc)
+{
+	char name [MAX_NAMELEN];
+
+	if (!root_irq_dir || !desc->dir)
+		return;
+#ifdef CONFIG_SMP
+	remove_proc_entry("smp_affinity", desc->dir);
+	remove_proc_entry("affinity_hint", desc->dir);
+	remove_proc_entry("node", desc->dir);
+#endif
+	remove_proc_entry("spurious", desc->dir);
+
+	memset(name, 0, MAX_NAMELEN);
+	sprintf(name, "%u", irq);
+	remove_proc_entry(name, root_irq_dir);
+}
+
 #undef MAX_NAMELEN
 
 void unregister_handler_proc(unsigned int irq, struct irqaction *action)