linux-kernel - question about drivers/dma/dma-jz4780.c

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Date:	Sun, 19 Jul 2015 11:08:49 +0200 (CEST)
From:	Julia Lawall <julia.lawall@...6.fr>
To:	Zubair.Kakakhel@...tec.com
cc:	dmaengine@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: question about drivers/dma/dma-jz4780.c

The file drivers/dma/dma-jz4780.c has a probe function that sets up irqs 
using devm_request_irq.  The probe function then ends with:

err_unregister_dev:
	dma_async_device_unregister(dd);

err_disable_clk:
        clk_disable_unprepare(jzdma->clk);
	return ret;
}

The remove function, on the other hand contains:

        of_dma_controller_free(pdev->dev.of_node);
        devm_free_irq(&pdev->dev, jzdma->irq, jzdma);
        dma_async_device_unregister(&jzdma->dma_device);

The need for calling devm_free_irq explicitly would be that it needs to 
occur before dma_async_device_unregister, to eg avoid a reference to a 
dangling pointer.  But devm_free_irq is implicitly called after the call 
to dma_async_device_unregister at the end of the probe function.  Which 
one is correct?

julia
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