linux-kernel - Re: [PATCH] dma: jz4780: fix call balance of jzdma->clk handling routines

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Message-ID: <b32939c57f1faff7ae33c072d5824d8225735de6.camel@crapouillou.net>
Date: Tue, 21 Jan 2025 00:48:13 +0100
From: Paul Cercueil <paul@...pouillou.net>
To: Vitalii Mordan <mordan@...ras.ru>
Cc: Vinod Koul <vkoul@...nel.org>, Alex Smith <alex.smith@...tec.com>, 
 Zubair Lutfullah Kakakhel	 <Zubair.Kakakhel@...tec.com>,
 linux-mips@...r.kernel.org, 	dmaengine@...r.kernel.org,
 linux-kernel@...r.kernel.org, Fedor Pchelkin	 <pchelkin@...ras.ru>, Alexey
 Khoroshilov <khoroshilov@...ras.ru>, Vadim Mutilin	 <mutilin@...ras.ru>,
 lvc-project@...uxtesting.org
Subject: Re: [PATCH] dma: jz4780: fix call balance of jzdma->clk handling
 routines

Hi Vitalii,

Le lundi 20 janvier 2025 à 16:50 +0300, Vitalii Mordan a écrit :
> If the clock jzdma->clk was not enabled in jz4780_dma_probe(), it
> should
> not be disabled in any path.
> 
> Conversely, if it was enabled in jz4780_dma_probe(), it must be
> disabled
> in all error paths to ensure proper cleanup.
> 
> Use the devm_clk_get_enabled() helper function to ensure proper call
> balance for jzdma->clk.
> 
> Found by Linux Verification Center (linuxtesting.org) with Klever.
> 
> Fixes: d894fc6046fe ("dmaengine: jz4780: add driver for the Ingenic
> JZ4780 DMA controller")
> Signed-off-by: Vitalii Mordan <mordan@...ras.ru>

Acked-by: Paul Cercueil <paul@...pouillou.net>

Cheers,
-Paul


> ---
>  drivers/dma/dma-jz4780.c | 14 ++++----------
>  1 file changed, 4 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/dma/dma-jz4780.c b/drivers/dma/dma-jz4780.c
> index 100057603fd4..ff9c387fd8c1 100644
> --- a/drivers/dma/dma-jz4780.c
> +++ b/drivers/dma/dma-jz4780.c
> @@ -896,15 +896,13 @@ static int jz4780_dma_probe(struct
> platform_device *pdev)
>  		return -EINVAL;
>  	}
>  
> -	jzdma->clk = devm_clk_get(dev, NULL);
> +	jzdma->clk = devm_clk_get_enabled(dev, NULL);
>  	if (IS_ERR(jzdma->clk)) {
> -		dev_err(dev, "failed to get clock\n");
> +		dev_err(dev, "failed to get and enable clock\n");
>  		ret = PTR_ERR(jzdma->clk);
>  		return ret;
>  	}
>  
> -	clk_prepare_enable(jzdma->clk);
> -
>  	/* Property is optional, if it doesn't exist the value will
> remain 0. */
>  	of_property_read_u32_index(dev->of_node, "ingenic,reserved-
> channels",
>  				   0, &jzdma->chan_reserved);
> @@ -972,7 +970,7 @@ static int jz4780_dma_probe(struct
> platform_device *pdev)
>  
>  	ret = platform_get_irq(pdev, 0);
>  	if (ret < 0)
> -		goto err_disable_clk;
> +		return ret;
>  
>  	jzdma->irq = ret;
>  
> @@ -980,7 +978,7 @@ static int jz4780_dma_probe(struct
> platform_device *pdev)
>  			  jzdma);
>  	if (ret) {
>  		dev_err(dev, "failed to request IRQ %u!\n", jzdma-
> >irq);
> -		goto err_disable_clk;
> +		return ret;
>  	}
>  
>  	ret = dmaenginem_async_device_register(dd);
> @@ -1002,9 +1000,6 @@ static int jz4780_dma_probe(struct
> platform_device *pdev)
>  
>  err_free_irq:
>  	free_irq(jzdma->irq, jzdma);
> -
> -err_disable_clk:
> -	clk_disable_unprepare(jzdma->clk);
>  	return ret;
>  }
>  
> @@ -1015,7 +1010,6 @@ static void jz4780_dma_remove(struct
> platform_device *pdev)
>  
>  	of_dma_controller_free(pdev->dev.of_node);
>  
> -	clk_disable_unprepare(jzdma->clk);
>  	free_irq(jzdma->irq, jzdma);
>  
>  	for (i = 0; i < jzdma->soc_data->nb_channels; i++)