[PATCH 14/18] x86: Replace setup_irq() by request_irq()

[afzal mohammed]

request_irq() is preferred over setup_irq(). Existing callers of
setup_irq() reached mostly via 'init_IRQ()' & 'time_init()', while
memory allocators are ready by 'mm_init()'.

Per tglx[1], setup_irq() existed in olden days when allocators were not
ready by the time early interrupts were initialized.

Hence replace setup_irq() by request_irq().

Seldom remove_irq() usage has been observed coupled with setup_irq(),
wherever that has been found, it too has been replaced by free_irq().

[1] https://lkml.kernel.org/r/alpine.DEB.2.20.1710191609480.1971@nanos

Signed-off-by: afzal mohammed <afzal.mohd.ma@xxxxxxxxx>
---

Since cc'ing cover letter to all maintainers/reviewers would be too
many, refer for cover letter,
 https://lkml.kernel.org/r/cover.1581478323.git.afzal.mohd.ma@xxxxxxxxx

 arch/x86/kernel/irqinit.c | 18 +++++++-----------
 arch/x86/kernel/time.c    | 10 +++-------
 2 files changed, 10 insertions(+), 18 deletions(-)

diff --git a/arch/x86/kernel/irqinit.c b/arch/x86/kernel/irqinit.c
index 16919a9671fa..8147075238bf 100644
--- a/arch/x86/kernel/irqinit.c
+++ b/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 +95,11 @@ 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("request_irq() on %s failed\n", "cascade");
+	}
 }
diff --git a/arch/x86/kernel/time.c b/arch/x86/kernel/time.c
index d8673d8a779b..0f9cb386d71f 100644
--- a/arch/x86/kernel/time.c
+++ b/arch/x86/kernel/time.c
@@ -62,19 +62,15 @@ 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)
 {
 	/*
 	 * Unconditionally register the legacy timer; 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,
+			IRQF_NOBALANCING | IRQF_IRQPOLL | IRQF_TIMER, "timer",
+			NULL))
 		pr_info("Failed to register legacy timer interrupt\n");
 }
 
-- 
2.24.1