linux-kernel - [PATCH] genirq: Restore trigger settings in irq_modify

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Message-Id: <20170818095345.12378-1-marc.zyngier@arm.com>
Date:   Fri, 18 Aug 2017 10:53:45 +0100
From:   Marc Zyngier <marc.zyngier@....com>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     linux-kernel@...r.kernel.org, Jon Hunter <jonathanh@...dia.com>,
        jeffy <jeffy.chen@...k-chips.com>
Subject: [PATCH] genirq: Restore trigger settings in irq_modify_status

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, let's snapshot the settings before clearing them,
and restore them if the whole purpose of irq_modify_status was not
change the trigger.

Cc: Jon Hunter <jonathanh@...dia.com>
Reported-by: jeffy <jeffy.chen@...k-chips.com>
Signed-off-by: Marc Zyngier <marc.zyngier@....com>
---
 kernel/irq/chip.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/kernel/irq/chip.c b/kernel/irq/chip.c
index a3cc37c0c85e..3675c6004f2a 100644
--- a/kernel/irq/chip.c
+++ b/kernel/irq/chip.c
@@ -1000,7 +1000,7 @@ EXPORT_SYMBOL_GPL(irq_set_chip_and_handler_name);
 
 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)
@@ -1014,6 +1014,8 @@ void irq_modify_status(unsigned int irq, unsigned long clr, unsigned long set)
 
 	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))
@@ -1025,7 +1027,11 @@ void irq_modify_status(unsigned int irq, unsigned long clr, unsigned long set)
 	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);
 }
-- 
2.11.0