genirq/chip: Rework handle_fasteoi_mask_irq()

Use the new helpers to decide whether the interrupt should be handled and
switch the descriptor locking to guard().

Note: The mask_irq() operation in the second condition was redundant as the
interrupt is already masked right at the beginning of the function.

Fixup the kernel doc comment while at it.

No functional change.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/all/20250429065421.175652864@linutronix.de

Author: KAGA-KOKO

kernel/irq/chip.c

@@ -1144,51 +1144,31 @@ void handle_fasteoi_ack_irq(struct irq_desc *desc)
 EXPORT_SYMBOL_GPL(handle_fasteoi_ack_irq);
 
 /**
- *	handle_fasteoi_mask_irq - irq handler for level hierarchy
- *	stacked on transparent controllers
+ * handle_fasteoi_mask_irq - irq handler for level hierarchy stacked on
+ *			     transparent controllers
  *
- *	@desc:	the interrupt description structure for this irq
+ * @desc:	the interrupt description structure for this irq
  *
- *	Like handle_fasteoi_irq(), but for use with hierarchy where
- *	the irq_chip also needs to have its ->irq_mask_ack() function
- *	called.
+ * Like handle_fasteoi_irq(), but for use with hierarchy where the irq_chip
+ * also needs to have its ->irq_mask_ack() function called.
  */
 void handle_fasteoi_mask_irq(struct irq_desc *desc)
 {
 	struct irq_chip *chip = desc->irq_data.chip;
 
-	raw_spin_lock(&desc->lock);
+	guard(raw_spinlock)(&desc->lock);
 	mask_ack_irq(desc);
 
-	if (!irq_can_handle_pm(desc))
-		goto out;
-
-	desc->istate &= ~(IRQS_REPLAY | IRQS_WAITING);
-
-	/*
-	 * If its disabled or no action available
-	 * then mask it and get out of here:
-	 */
-	if (unlikely(!desc->action || irqd_irq_disabled(&desc->irq_data))) {
-		desc->istate |= IRQS_PENDING;
-		mask_irq(desc);
-		goto out;
+	if (!irq_can_handle(desc)) {
+		cond_eoi_irq(chip, &desc->irq_data);
+		return;
 	}
 
 	kstat_incr_irqs_this_cpu(desc);
-	if (desc->istate & IRQS_ONESHOT)
-		mask_irq(desc);
 
 	handle_irq_event(desc);
 
 	cond_unmask_eoi_irq(desc, chip);
-
-	raw_spin_unlock(&desc->lock);
-	return;
-out:
-	if (!(chip->flags & IRQCHIP_EOI_IF_HANDLED))
-		chip->irq_eoi(&desc->irq_data);
-	raw_spin_unlock(&desc->lock);
 }
 EXPORT_SYMBOL_GPL(handle_fasteoi_mask_irq);