x86/irq: Remove vector_used_by_percpu_irq()

Last user (lguest) is gone. Remove it.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/20170828064956.201432430@linutronix.deSigned-off-by: Ingo Molnar <mingo@kernel.org>

arch/x86/include/asm/irq.h

@@ -44,7 +44,6 @@ extern __visible unsigned int do_IRQ(struct pt_regs *regs);
 
 /* Interrupt vector management */
 extern DECLARE_BITMAP(used_vectors, NR_VECTORS);
-extern int vector_used_by_percpu_irq(unsigned int vector);
 
 extern void init_ISA_irqs(void);
 

arch/x86/kernel/irq.c

@@ -346,8 +346,6 @@ __visible void __irq_entry smp_trace_x86_platform_ipi(struct pt_regs *regs)
 	set_irq_regs(old_regs);
 }
 
-EXPORT_SYMBOL_GPL(vector_used_by_percpu_irq);
-
 #ifdef CONFIG_HOTPLUG_CPU
 
 /* These two declarations are only used in check_irq_vectors_for_cpu_disable()

arch/x86/kernel/irqinit.c

@@ -55,18 +55,6 @@ DEFINE_PER_CPU(vector_irq_t, vector_irq) = {
 	[0 ... NR_VECTORS - 1] = VECTOR_UNUSED,
 };
 
-int vector_used_by_percpu_irq(unsigned int vector)
-{
-	int cpu;
-
-	for_each_online_cpu(cpu) {
-		if (!IS_ERR_OR_NULL(per_cpu(vector_irq, cpu)[vector]))
-			return 1;
-	}
-
-	return 0;
-}
-
 void __init init_ISA_irqs(void)
 {
 	struct irq_chip *chip = legacy_pic->chip;