[tip:irq/core] genirq/cpuhotplug: Add support for conditional masking

[tip-bot for Thomas Gleixner]

Commit-ID:  47a06d3a783217acae02976f15ca07ddc1ac024f
Gitweb:     http://git.kernel.org/tip/47a06d3a783217acae02976f15ca07ddc1ac024f
Author:     Thomas Gleixner <tglx@xxxxxxxxxxxxx>
AuthorDate: Tue, 20 Jun 2017 01:37:30 +0200
Committer:  Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitDate: Thu, 22 Jun 2017 18:21:17 +0200

genirq/cpuhotplug: Add support for conditional masking

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>
Cc: Jens Axboe <axboe@xxxxxxxxx>
Cc: Marc Zyngier <marc.zyngier@xxxxxxx>
Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Cc: Keith Busch <keith.busch@xxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Link: http://lkml.kernel.org/r/20170619235445.604565591@xxxxxxxxxxxxx

---
 kernel/irq/cpuhotplug.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/kernel/irq/cpuhotplug.c b/kernel/irq/cpuhotplug.c
index 4be4bd6..6f46587 100644
--- a/kernel/irq/cpuhotplug.c
+++ b/kernel/irq/cpuhotplug.c
@@ -18,6 +18,7 @@ static bool migrate_one_irq(struct irq_desc *desc)
 {
 	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_desc *desc)
 	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_desc *desc)
 	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;
 }