linux-kernel - [PATCH v3] genirq: Check irq disabled & masked states in irq

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Message-Id: <1495879508-17491-1-git-send-email-jeffy.chen@rock-chips.com>
Date:   Sat, 27 May 2017 18:05:08 +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 v3] genirq: Check irq disabled & masked states in irq_shutdown

If a irq is already disabled, irq_shutdown may try to disable it again,
for example:
devm_request_irq->irq_startup->irq_enable
disable_irq					<-- disabled
devm_free_irq->irq_shutdown			<-- disable it again

This would confuse some chips which require balanced irq enable and
disable, for example pinctrl-rockchip & pinctrl-nomadik.

Add a state check before calling irq_disable to prevent that.

v2: Rewrite commit message.
v3: Rewrite commit message and not skip irq_shutdown.

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

Changes in v3:
Rewrite commit message and not skip irq_shutdown.

Changes in v2:
Rewrite commit message.

 kernel/irq/chip.c | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/kernel/irq/chip.c b/kernel/irq/chip.c
index 686be4b..0ac0c56 100644
--- a/kernel/irq/chip.c
+++ b/kernel/irq/chip.c
@@ -206,13 +206,23 @@ int irq_startup(struct irq_desc *desc, bool resend)
 
 void irq_shutdown(struct irq_desc *desc)
 {
+	int irq_disabled = irqd_irq_disabled(&desc->irq_data);
+
 	irq_state_set_disabled(desc);
 	desc->depth = 1;
 	if (desc->irq_data.chip->irq_shutdown)
 		desc->irq_data.chip->irq_shutdown(&desc->irq_data);
-	else if (desc->irq_data.chip->irq_disable)
+	/*
+	 * 1/ Some chips may require balanced irq enable &_disable.
+	 * 2/ Due to the lazy disable approach, a irq could be
+	 *    disabled but unmasked.
+	 *
+	 * So if this irq is already disabled, let's mask it instead
+	 * of trying to call irq_disable again.
+	 */
+	else if (desc->irq_data.chip->irq_disable && !irq_disabled)
 		desc->irq_data.chip->irq_disable(&desc->irq_data);
-	else
+	else if (desc->irq_data.chip->irq_mask)
 		desc->irq_data.chip->irq_mask(&desc->irq_data);
 	irq_domain_deactivate_irq(&desc->irq_data);
 	irq_state_set_masked(desc);
-- 
2.1.4