linux-kernel - [PATCH v2 3/3] genirq: Do not test disabled IRQs with DEBUG

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Message-Id: <1592208439-17594-3-git-send-email-krzk@kernel.org>
Date:   Mon, 15 Jun 2020 10:07:19 +0200
From:   Krzysztof Kozlowski <krzk@...nel.org>
To:     Mark Brown <broonie@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Vladimir Oltean <vladimir.oltean@....com>,
        linux-spi@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     Marc Kleine-Budde <mkl@...gutronix.de>,
        Wolfram Sang <wsa@...nel.org>, kernel@...gutronix.de,
        Krzysztof Kozlowski <krzk@...nel.org>
Subject: [PATCH v2 3/3] genirq: Do not test disabled IRQs with DEBUG_SHIRQ

Testing events during freeing of disabled shared interrupts
(CONFIG_DEBUG_SHIRQ) leads to false positives.  The driver disabled
interrupts on purpose to be sure that they will not fire during device
removal.

Signed-off-by: Krzysztof Kozlowski <krzk@...nel.org>

---

Changes since v1:
1. New patch.
---
 kernel/irq/manage.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index 761911168438..f19f0dedc30d 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -1775,12 +1775,14 @@ static struct irqaction *__free_irq(struct irq_desc *desc, void *dev_id)
 	/*
 	 * It's a shared IRQ -- the driver ought to be prepared for an IRQ
 	 * event to happen even now it's being freed, so let's make sure that
-	 * is so by doing an extra call to the handler ....
+	 * is so by doing an extra call to the handler.
+	 * Although the driver could disable the interrupts just before freeing
+	 * just to avoid such trouble - don't test it then.
 	 *
 	 * ( We do this after actually deregistering it, to make sure that a
 	 *   'real' IRQ doesn't run in parallel with our fake. )
 	 */
-	if (action->flags & IRQF_SHARED) {
+	if (action->flags & IRQF_SHARED && !desc->depth) {
 		local_irq_save(flags);
 		action->handler(irq, dev_id);
 		local_irq_restore(flags);
-- 
2.7.4