Re: [PATCH v2] i2c: tegra: Fix failure during probe deferral cleanup

[Thierry Reding <thierry.reding@gmail.com>]

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On Fri, Jul 07, 2023 at 03:26:19PM +0200, Thierry Reding wrote:
> From: Thierry Reding <treding@nvidia.com>
> 
> If the driver fails to obtain a DMA channel, it will initiate cleanup
> and try to release the DMA channel that couldn't be retrieved. This will
> cause a crash because the cleanup will try to dereference an ERR_PTR()-
> encoded error code.
> 
> However, there's nothing to clean up at this point yet, so we can avoid
> this by simply resetting the DMA channel to NULL instead of storing the
> error code.
> 
> Fixes: fcc8a89a1c83 ("i2c: tegra: Share same DMA channel for RX and TX")
> Signed-off-by: Thierry Reding <treding@nvidia.com>
> ---
> Changes in v2:
> - simplify patch by setting dma_chan = NULL on channel request failure
> 
>  drivers/i2c/busses/i2c-tegra.c | 1 +
>  1 file changed, 1 insertion(+)

Hi Andy, Wolfram,

do you have any reservations about this? This fixes a bug that was
introduced in v6.5-rc1, so it'd be great if this could make v6.5.

Thanks,
Thierry

> 
> diff --git a/drivers/i2c/busses/i2c-tegra.c b/drivers/i2c/busses/i2c-tegra.c
> index f155e9028f94..2a13f11edfd1 100644
> --- a/drivers/i2c/busses/i2c-tegra.c
> +++ b/drivers/i2c/busses/i2c-tegra.c
> @@ -460,6 +460,7 @@ static int tegra_i2c_init_dma(struct tegra_i2c_dev *i2c_dev)
>  	i2c_dev->dma_chan = dma_request_chan(i2c_dev->dev, "tx");
>  	if (IS_ERR(i2c_dev->dma_chan)) {
>  		err = PTR_ERR(i2c_dev->dma_chan);
> +		i2c_dev->dma_chan = NULL;
>  		goto err_out;
>  	}
>  
> -- 
> 2.41.0
> 

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