From ee6459d60f24d91052f0288155f44e6a7f991050 Mon Sep 17 00:00:00 2001
From: Samuel Holland <samuel@sholland.org>
Date: Sat, 7 May 2022 18:34:25 -0500
Subject: [PATCH 011/117] genirq: Add support for oneshot-safe threaded EOIs

irqchips can use the combination of flags IRQCHIP_ONESHOT_SAFE |
IRQCHIP_EOI_THREADED to elide mask operations.

Signed-off-by: Samuel Holland <samuel@sholland.org>
---
 kernel/irq/chip.c      | 36 +++++++++++++++++-------------------
 kernel/irq/internals.h |  2 +-
 kernel/irq/manage.c    | 12 ++++++------
 3 files changed, 24 insertions(+), 26 deletions(-)

--- a/kernel/irq/chip.c
+++ b/kernel/irq/chip.c
@@ -439,16 +439,6 @@ void unmask_irq(struct irq_desc *desc)
 	}
 }
 
-void unmask_threaded_irq(struct irq_desc *desc)
-{
-	struct irq_chip *chip = desc->irq_data.chip;
-
-	if (chip->flags & IRQCHIP_EOI_THREADED)
-		chip->irq_eoi(&desc->irq_data);
-
-	unmask_irq(desc);
-}
-
 /*
  *	handle_nested_irq - Handle a nested irq from a irq thread
  *	@irq:	the interrupt number
@@ -656,25 +646,33 @@ out_unlock:
 }
 EXPORT_SYMBOL_GPL(handle_level_irq);
 
-static void cond_unmask_eoi_irq(struct irq_desc *desc, struct irq_chip *chip)
+void unmask_eoi_threaded_irq(struct irq_desc *desc)
 {
-	if (!(desc->istate & IRQS_ONESHOT)) {
+	struct irq_chip *chip = desc->irq_data.chip;
+
+	if (desc->istate & IRQS_ONESHOT)
+		unmask_irq(desc);
+
+	if (chip->flags & IRQCHIP_EOI_THREADED)
 		chip->irq_eoi(&desc->irq_data);
+}
+
+static void cond_unmask_eoi_irq(struct irq_desc *desc, struct irq_chip *chip)
+{
+	/* Do not send EOI if the thread will do it for us. */
+	if ((chip->flags & IRQCHIP_EOI_THREADED) && desc->threads_oneshot)
 		return;
-	}
+
 	/*
 	 * We need to unmask in the following cases:
 	 * - Oneshot irq which did not wake the thread (caused by a
 	 *   spurious interrupt or a primary handler handling it
 	 *   completely).
 	 */
-	if (!irqd_irq_disabled(&desc->irq_data) &&
-	    irqd_irq_masked(&desc->irq_data) && !desc->threads_oneshot) {
-		chip->irq_eoi(&desc->irq_data);
+	if ((desc->istate & IRQS_ONESHOT) && !desc->threads_oneshot)
 		unmask_irq(desc);
-	} else if (!(chip->flags & IRQCHIP_EOI_THREADED)) {
-		chip->irq_eoi(&desc->irq_data);
-	}
+
+	chip->irq_eoi(&desc->irq_data);
 }
 
 /**
--- a/kernel/irq/internals.h
+++ b/kernel/irq/internals.h
@@ -93,7 +93,7 @@ extern void irq_percpu_enable(struct irq
 extern void irq_percpu_disable(struct irq_desc *desc, unsigned int cpu);
 extern void mask_irq(struct irq_desc *desc);
 extern void unmask_irq(struct irq_desc *desc);
-extern void unmask_threaded_irq(struct irq_desc *desc);
+extern void unmask_eoi_threaded_irq(struct irq_desc *desc);
 
 #ifdef CONFIG_SPARSE_IRQ
 static inline void irq_mark_irq(unsigned int irq) { }
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -1074,9 +1074,9 @@ static int irq_wait_for_interrupt(struct
 static void irq_finalize_oneshot(struct irq_desc *desc,
 				 struct irqaction *action)
 {
-	if (!(desc->istate & IRQS_ONESHOT) ||
-	    action->handler == irq_forced_secondary_handler)
+	if (action->handler == irq_forced_secondary_handler)
 		return;
+
 again:
 	chip_bus_lock(desc);
 	raw_spin_lock_irq(&desc->lock);
@@ -1112,9 +1112,8 @@ again:
 
 	desc->threads_oneshot &= ~action->thread_mask;
 
-	if (!desc->threads_oneshot && !irqd_irq_disabled(&desc->irq_data) &&
-	    irqd_irq_masked(&desc->irq_data))
-		unmask_threaded_irq(desc);
+	if (!desc->threads_oneshot)
+		unmask_eoi_threaded_irq(desc);
 
 out_unlock:
 	raw_spin_unlock_irq(&desc->lock);
@@ -1662,7 +1661,8 @@ __setup_irq(unsigned int irq, struct irq
 	 * !ONESHOT irqs the thread mask is 0 so we can avoid a
 	 * conditional in irq_wake_thread().
 	 */
-	if (new->flags & IRQF_ONESHOT) {
+	if ((new->flags & IRQF_ONESHOT) ||
+	    (desc->irq_data.chip->flags & (IRQCHIP_ONESHOT_SAFE | IRQCHIP_EOI_THREADED)) == (IRQCHIP_ONESHOT_SAFE | IRQCHIP_EOI_THREADED)) {
 		/*
 		 * Unlikely to have 32 resp 64 irqs sharing one line,
 		 * but who knows.