linux-kernel - [PATCH v3] x86: Replace setup_irq() by request

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Date:   Sat, 29 Feb 2020 18:25:07 +0530
From:   afzal mohammed <afzal.mohd.ma@...il.com>
To:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
        Juergen Gross <jgross@...e.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        linux-kernel@...r.kernel.org
Cc:     afzal mohammed <afzal.mohd.ma@...il.com>
Subject: [PATCH v3] x86: Replace setup_irq() by request_irq()

request_irq() is preferred over setup_irq(). Invocations of setup_irq()
occur after memory allocators are ready.

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().

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

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

v3:
 * Instead of tree wide series, arch specific patch
 * Strip irrelevant portions & more tweaking in commit message
 * Remove name indirection in pr_err string & modify to the form
	"Failed to request irq 2 (cascade)\n"
 * Use local variable for flags to improve readability
v2:
 * Replace pr_err("request_irq() on %s failed" by
           pr_err("%s: request_irq() failed"
 * Commit message massage

 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..d750178fc192 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("Failed to request irq 2 (cascade)\n");
+	}
 }
diff --git a/arch/x86/kernel/time.c b/arch/x86/kernel/time.c
index d8673d8a779b..6acc1baa4a52 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)
 {
+	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.
 	 */
-	if (setup_irq(0, &irq0))
+	if (request_irq(0, timer_interrupt, flags, "timer", NULL))
 		pr_info("Failed to register legacy timer interrupt\n");
 }
 
-- 
2.25.1