linux-kernel - Re: [PATCH 24/25] dmaengine: dw-edma: Skip cleanup procedure if no private data found

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Date:   Fri, 25 Mar 2022 23:45:03 +0530
From:   Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
To:     Serge Semin <Sergey.Semin@...kalelectronics.ru>
Cc:     Gustavo Pimentel <gustavo.pimentel@...opsys.com>,
        Vinod Koul <vkoul@...nel.org>,
        Jingoo Han <jingoohan1@...il.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Frank Li <Frank.Li@....com>,
        Serge Semin <fancer.lancer@...il.com>,
        Alexey Malahov <Alexey.Malahov@...kalelectronics.ru>,
        Pavel Parkhomenko <Pavel.Parkhomenko@...kalelectronics.ru>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Rob Herring <robh@...nel.org>,
        Krzysztof Wilczyński <kw@...ux.com>,
        linux-pci@...r.kernel.org, dmaengine@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 24/25] dmaengine: dw-edma: Skip cleanup procedure if no
 private data found

On Thu, Mar 24, 2022 at 04:48:35AM +0300, Serge Semin wrote:
> DW eDMA driver private data is preserved in the passed DW eDMA chip info
> structure. If either probe procedure failed or for some reason the passed
> info object doesn't have private data pointer initialized we need to halt
> the DMA device cleanup procedure in order to prevent possible system
> crashes.
> 

How come remove() could happen when probe() failed? If you hit this issue then
something else is utterly going wrong.

Thanks,
Mani

> Signed-off-by: Serge Semin <Sergey.Semin@...kalelectronics.ru>
> ---
>  drivers/dma/dw-edma/dw-edma-core.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/dma/dw-edma/dw-edma-core.c b/drivers/dma/dw-edma/dw-edma-core.c
> index ca5cd7c99571..b932682a8ba8 100644
> --- a/drivers/dma/dw-edma/dw-edma-core.c
> +++ b/drivers/dma/dw-edma/dw-edma-core.c
> @@ -1030,6 +1030,10 @@ int dw_edma_remove(struct dw_edma_chip *chip)
>  	struct dw_edma *dw = chip->dw;
>  	int i;
>  
> +	/* Skip removal if no private data found */
> +	if (!dw)
> +		return -ENODEV;
> +
>  	/* Disable eDMA */
>  	dw_edma_v0_core_off(dw);
>  
> -- 
> 2.35.1
>