linux-kernel - [PATCH 3/4] media: dw100: Fix kernel oops with PREEMPT

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Message-Id: <20260105-sklug-v6-16-topic-dw100-v3-1-dev-v1-3-65af34d04fd8@ideasonboard.com>
Date: Mon, 05 Jan 2026 12:35:55 +0100
From: Stefan Klug <stefan.klug@...asonboard.com>
To: Xavier Roumegue <xavier.roumegue@....nxp.com>, 
 Mauro Carvalho Chehab <mchehab@...nel.org>, 
 Sebastian Andrzej Siewior <bigeasy@...utronix.de>, 
 Clark Williams <clrkwllms@...nel.org>, Steven Rostedt <rostedt@...dmis.org>, 
 Laurent Pinchart <laurent.pinchart@...asonboard.com>
Cc: linux-media@...r.kernel.org, linux-kernel@...r.kernel.org, 
 linux-rt-devel@...ts.linux.dev, Stefan Klug <stefan.klug@...asonboard.com>
Subject: [PATCH 3/4] media: dw100: Fix kernel oops with PREEMPT_RT enabled

On kernels with PREEMPT_RT enabled, a "BUG: scheduling while atomic"
kernel oops occurs inside dw100_irq_handler -> vb2_buffer_done. This is
because vb2_buffer_done takes a spinlock which is not allowed within
interrupt context on PREEMPT_RT.

Fix that by making the irq handler threaded. The threaded interrupt
handling might cause the interrupt line to be disabled a little longer
than before. As the line is not shared, this has no negative side
effects.

Signed-off-by: Stefan Klug <stefan.klug@...asonboard.com>
---
 drivers/media/platform/nxp/dw100/dw100.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/media/platform/nxp/dw100/dw100.c b/drivers/media/platform/nxp/dw100/dw100.c
index 8a421059a1c9b55f514a29d3c2c5a6ffb76e0a64..4f5ef70e5f4a052fb5f208e35f8785f9d30dc54e 100644
--- a/drivers/media/platform/nxp/dw100/dw100.c
+++ b/drivers/media/platform/nxp/dw100/dw100.c
@@ -1600,8 +1600,9 @@ static int dw100_probe(struct platform_device *pdev)
 
 	pm_runtime_put_sync(&pdev->dev);
 
-	ret = devm_request_irq(&pdev->dev, irq, dw100_irq_handler, IRQF_ONESHOT,
-			       dev_name(&pdev->dev), dw_dev);
+	ret = devm_request_threaded_irq(&pdev->dev, irq, NULL,
+					dw100_irq_handler, IRQF_ONESHOT,
+					dev_name(&pdev->dev), dw_dev);
 	if (ret < 0) {
 		dev_err(&pdev->dev, "Failed to request irq: %d\n", ret);
 		goto err_pm;

-- 
2.51.0