Patch "genirq: Restore trigger settings in irq_modify_status()" has been added to the 4.9-stable tree

This is a note to let you know that I've just added the patch titled

genirq: Restore trigger settings in irq_modify_status()

to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
genirq-restore-trigger-settings-in-irq_modify_status.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Marc Zyngier <[email protected]>
Date: Fri, 18 Aug 2017 10:53:45 +0100
Subject: genirq: Restore trigger settings in irq_modify_status()

From: Marc Zyngier <[email protected]>

commit e8f241893dfbbebe2813c01eac54f263e6a5e59c upstream.

irq_modify_status starts by clearing the trigger settings from irq_data before applying the new settings, but doesn't restore them, leaving them to IRQ_TYPE_NONE.

That's pretty confusing to the potential request_irq() that could follow. Instead, snapshot the settings before clearing them, and restore them if the irq_modify_status() invocation was not changing the trigger.

---
 kernel/irq/chip.c |   10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

@@ -895,13 +895,15 @@ EXPORT_SYMBOL_GPL(irq_set_chip_and_handl
 
 void irq_modify_status(unsigned int irq, unsigned long clr, unsigned long set)
 {
-	unsigned long flags;
+	unsigned long flags, trigger, tmp;
 	struct irq_desc *desc = irq_get_desc_lock(irq, &flags, 0);
 
 	if (!desc)
 		return;
 	irq_settings_clr_and_set(desc, clr, set);
 
+	trigger = irqd_get_trigger_type(&desc->irq_data);
+
 	irqd_clear(&desc->irq_data, IRQD_NO_BALANCING | IRQD_PER_CPU |
 		   IRQD_TRIGGER_MASK | IRQD_LEVEL | IRQD_MOVE_PCNTXT);
 	if (irq_settings_has_no_balance_set(desc))

@@ -913,7 +915,11 @@ void irq_modify_status(unsigned int irq,
 	if (irq_settings_is_level(desc))
 		irqd_set(&desc->irq_data, IRQD_LEVEL);
 
-	irqd_set(&desc->irq_data, irq_settings_get_trigger_mask(desc));
+	tmp = irq_settings_get_trigger_mask(desc);
+	if (tmp != IRQ_TYPE_NONE)
+		trigger = tmp;
+
+	irqd_set(&desc->irq_data, trigger);
 
 	irq_put_desc_unlock(desc, flags);
 }

Patches currently in stable-queue which might be from [email protected] are

queue-4.9/genirq-restore-trigger-settings-in-irq_modify_status.patch queue-4.9/irqchip-atmel-aic-fix-unbalanced-of_node_put-in-aic_common_irq_fixup.patch queue-4.9/irqchip-atmel-aic-fix-unbalanced-refcount-in-aic_common_rtc_irq_fixup.patch