[patch 30/55] genirq/cpuhotplug: Add support for conditional masking

[Thomas Gleixner]

Interrupts which cannot be migrated in process context, need to be masked
before the affinity is changed forcefully.

Add support for that. Will be compiled out for architectures which do not
have this x86 specific issue.

Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
---
 kernel/irq/cpuhotplug.c |   11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

--- a/kernel/irq/cpuhotplug.c
+++ b/kernel/irq/cpuhotplug.c
@@ -18,6 +18,7 @@ static bool migrate_one_irq(struct irq_d
 {
 	struct irq_data *d = irq_desc_get_irq_data(desc);
 	struct irq_chip *chip = irq_data_get_irq_chip(d);
+	bool maskchip = !irq_can_move_pcntxt(d) && !irqd_irq_masked(d);
 	const struct cpumask *affinity;
 	bool brokeaff = false;
 	int err;
@@ -69,6 +70,10 @@ static bool migrate_one_irq(struct irq_d
 	if (irq_fixup_move_pending(desc, true))
 		affinity = irq_desc_get_pending_mask(desc);
 
+	/* Mask the chip for interrupts which cannot move in process context */
+	if (maskchip && chip->irq_mask)
+		chip->irq_mask(d);
+
 	if (cpumask_any_and(affinity, cpu_online_mask) >= nr_cpu_ids) {
 		affinity = cpu_online_mask;
 		brokeaff = true;
@@ -78,8 +83,12 @@ static bool migrate_one_irq(struct irq_d
 	if (err) {
 		pr_warn_ratelimited("IRQ%u: set affinity failed(%d).\n",
 				    d->irq, err);
-		return false;
+		brokeaff = false;
 	}
+
+	if (maskchip && chip->irq_unmask)
+		chip->irq_unmask(d);
+
 	return brokeaff;
 }