linux-kernel - [PATCH v2] genirq: Check irq disabled & masked states in irq

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Date:   Sat, 27 May 2017 12:52:45 +0800
From:   Jeffy Chen <jeffy.chen@...k-chips.com>
To:     linux-kernel@...r.kernel.org, tglx@...utronix.de
Cc:     briannorris@...omium.org, dianders@...omium.org,
        tfiga@...omium.org, Jeffy Chen <jeffy.chen@...k-chips.com>
Subject: [PATCH v2] genirq: Check irq disabled & masked states in irq_shutdown

If a irq is already disabled & masked, free_irq may cause a unbalanced
irq shutdown/disable/mask, for example:

devm_request_irq->irq_startup->irq_enable
disable_irq					<-- disabled and masked
devm_free_irq->irq_shutdown			<-- try to disable it again

This would confuse some pinctrl drivers which would control clk in
irq_enable/irq_disable, for example pinctrl-rockchip/pinctrl-nomadik.

This patch add a state check in irq_shutdown to prevent that.

v2: Rewrite commit message.

Signed-off-by: Jeffy Chen <jeffy.chen@...k-chips.com>
---

Changes in v2:
Rewrite commit message.

 kernel/irq/chip.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/kernel/irq/chip.c b/kernel/irq/chip.c
index 686be4b..816da03 100644
--- a/kernel/irq/chip.c
+++ b/kernel/irq/chip.c
@@ -206,14 +206,20 @@ int irq_startup(struct irq_desc *desc, bool resend)
 
 void irq_shutdown(struct irq_desc *desc)
 {
-	irq_state_set_disabled(desc);
 	desc->depth = 1;
+
+	if (unlikely(irqd_irq_disabled(&desc->irq_data) &&
+		irqd_irq_masked(&desc->irq_data)))
+		goto out;
+
+	irq_state_set_disabled(desc);
 	if (desc->irq_data.chip->irq_shutdown)
 		desc->irq_data.chip->irq_shutdown(&desc->irq_data);
 	else if (desc->irq_data.chip->irq_disable)
 		desc->irq_data.chip->irq_disable(&desc->irq_data);
 	else
 		desc->irq_data.chip->irq_mask(&desc->irq_data);
+out:
 	irq_domain_deactivate_irq(&desc->irq_data);
 	irq_state_set_masked(desc);
 }
-- 
2.1.4