[ldv-project] [PATCH v2] drivers/dma/dma-jz4780: Fix race condition between probe and irq handler

Fri Aug 21 20:01:57 MSK 2020

Le ven. 21 août 2020 à 9:14, madhuparnabhowmik10 at gmail.com a écrit :
> From: Madhuparna Bhowmik <madhuparnabhowmik10 at gmail.com>
>> In probe, IRQ is requested before zchan->id is initialized which can 
> be
> read in the irq handler. Hence, shift request irq after other 
> initializations
> complete.
>> Found by Linux Driver Verification project (linuxtesting.org).
>> Signed-off-by: Madhuparna Bhowmik <madhuparnabhowmik10 at gmail.com>

Reviewed-by: Paul Cercueil <paul at crapouillou.net>
Thanks for the patch.
Cheers,
-Paul
>> ---
> Changes since v1:
> Keep enable clock before request IRQ.
> ---
> drivers/dma/dma-jz4780.c | 38 +++++++++++++++++++-------------------
> 1 file changed, 19 insertions(+), 19 deletions(-)
>> diff --git a/drivers/dma/dma-jz4780.c b/drivers/dma/dma-jz4780.c
> index 448f663da89c..8beed91428bd 100644
> --- a/drivers/dma/dma-jz4780.c
> +++ b/drivers/dma/dma-jz4780.c
> @@ -879,24 +879,11 @@ static int jz4780_dma_probe(struct 
> platform_device *pdev)
> 		return -EINVAL;
> 	}
>> -	ret = platform_get_irq(pdev, 0);
> -	if (ret < 0)
> -		return ret;
> -
> -	jzdma->irq = ret;
> -
> -	ret = request_irq(jzdma->irq, jz4780_dma_irq_handler, 0, 
> dev_name(dev),
> -			 jzdma);
> -	if (ret) {
> -		dev_err(dev, "failed to request IRQ %u!\n", jzdma->irq);
> -		return ret;
> -	}
> -
> 	jzdma->clk = devm_clk_get(dev, NULL);
> 	if (IS_ERR(jzdma->clk)) {
> 		dev_err(dev, "failed to get clock\n");
> 		ret = PTR_ERR(jzdma->clk);
> -		goto err_free_irq;
> +		return ret;
> 	}
>> 	clk_prepare_enable(jzdma->clk);
> @@ -949,10 +936,23 @@ static int jz4780_dma_probe(struct 
> platform_device *pdev)
> 		jzchan->vchan.desc_free = jz4780_dma_desc_free;
> 	}
>> +	ret = platform_get_irq(pdev, 0);
> +	if (ret < 0)
> +		goto err_disable_clk;
> +
> +	jzdma->irq = ret;
> +
> +	ret = request_irq(jzdma->irq, jz4780_dma_irq_handler, 0, 
> dev_name(dev),
> +			 jzdma);
> +	if (ret) {
> +		dev_err(dev, "failed to request IRQ %u!\n", jzdma->irq);
> +		goto err_disable_clk;
> +	}
> +
> 	ret = dmaenginem_async_device_register(dd);
> 	if (ret) {
> 		dev_err(dev, "failed to register device\n");
> -		goto err_disable_clk;
> +		goto err_free_irq;
> 	}
>> 	/* Register with OF DMA helpers. */
> @@ -960,17 +960,17 @@ static int jz4780_dma_probe(struct 
> platform_device *pdev)
> 					 jzdma);
> 	if (ret) {
> 		dev_err(dev, "failed to register OF DMA controller\n");
> -		goto err_disable_clk;
> +		goto err_free_irq;
> 	}
>> 	dev_info(dev, "JZ4780 DMA controller initialised\n");
> 	return 0;
>> -err_disable_clk:
> -	clk_disable_unprepare(jzdma->clk);
> -
> err_free_irq:
> 	free_irq(jzdma->irq, jzdma);
> +
> +err_disable_clk:
> +	clk_disable_unprepare(jzdma->clk);
> 	return ret;
> }
>> --
> 2.17.1
>