x86: Replace setup_irq() by request_irq()

request_irq() is preferred over setup_irq(). The early boot setup_irq()
invocations happen either via 'init_IRQ()' or 'time_init()', while
memory allocators are ready by 'mm_init()'.

setup_irq() was required in old kernels when allocators were not ready by
the time early interrupts were initialized.

Hence replace setup_irq() by request_irq().

[ tglx: Use a local variable and get rid of the line break. Tweak the
  	comment a bit ]
Signed-off-by: afzal mohammed <afzal.mohd.ma@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/17f85021f6877650a5b09e0212d88323e6a30fd0.1582471508.git.afzal.mohd.ma@gmail.com

arch/x86/kernel/irqinit.c

@@ -44,15 +44,6 @@
  * (these are usually mapped into the 0x30-0xff vector range)
  */
 
-/*
- * IRQ2 is cascade interrupt to second interrupt controller
- */
-static struct irqaction irq2 = {
-	.handler = no_action,
-	.name = "cascade",
-	.flags = IRQF_NO_THREAD,
-};
-
 DEFINE_PER_CPU(vector_irq_t, vector_irq) = {
 	[0 ... NR_VECTORS - 1] = VECTOR_UNUSED,
 };
@@ -104,6 +95,9 @@ void __init native_init_IRQ(void)
 	idt_setup_apic_and_irq_gates();
 	lapic_assign_system_vectors();
 
-	if (!acpi_ioapic && !of_ioapic && nr_legacy_irqs())
-		setup_irq(2, &irq2);
+	if (!acpi_ioapic && !of_ioapic && nr_legacy_irqs()) {
+		/* IRQ2 is cascade interrupt to second interrupt controller */
+		if (request_irq(2, no_action, IRQF_NO_THREAD, "cascade", NULL))
+			pr_err("%s: request_irq() failed\n", "cascade");
+	}
 }

arch/x86/kernel/time.c

@@ -62,19 +62,16 @@ static irqreturn_t timer_interrupt(int irq, void *dev_id)
 	return IRQ_HANDLED;
 }
 
-static struct irqaction irq0  = {
-	.handler = timer_interrupt,
-	.flags = IRQF_NOBALANCING | IRQF_IRQPOLL | IRQF_TIMER,
-	.name = "timer"
-};
-
 static void __init setup_default_timer_irq(void)
 {
+	unsigned long flags = IRQF_NOBALANCING | IRQF_IRQPOLL | IRQF_TIMER;
+
 	/*
-	 * Unconditionally register the legacy timer; even without legacy
-	 * PIC/PIT we need this for the HPET0 in legacy replacement mode.
+	 * Unconditionally register the legacy timer interrupt; even
+	 * without legacy PIC/PIT we need this for the HPET0 in legacy
+	 * replacement mode.
 	 */
-	if (setup_irq(0, &irq0))
+	if (request_irq(0, timer_interrupt, flags, "timer", NULL))
 		pr_info("Failed to register legacy timer interrupt\n");
 }