Re: [PATCH] of: restricted dma: Fix condition for rmem init

[Will Deacon]

On Fri, Sep 17, 2021 at 02:14:23PM +0100, David Brazdil wrote:
> of_dma_set_restricted_buffer fails to handle negative return values from
> of_property_count_elems_of_size, e.g. when the property does not exist.
> This results in an attempt to assign a non-existent reserved memory
> region to the device and a warning being printed. Fix the condition to
> take negative values into account.
> 
> Fixes: f3cfd136aef0 ("of: restricted dma: Don't fail device probe on
> rmem init failure")
> Cc: Will Deacon <will@xxxxxxxxxx>
> Signed-off-by: David Brazdil <dbrazdil@xxxxxxxxxx>
> ---
>  drivers/of/device.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/of/device.c b/drivers/of/device.c
> index 5b043ee30824..b0800c260f64 100644
> --- a/drivers/of/device.c
> +++ b/drivers/of/device.c
> @@ -85,7 +85,11 @@ of_dma_set_restricted_buffer(struct device *dev, struct device_node *np)
>  			break;
>  	}
>  
> -	if (i != count && of_reserved_mem_device_init_by_idx(dev, of_node, i))
> +	/*
> +	 * Attempt to initialize a restricted-dma-pool region if one was found.
> +	 * Note that count can hold a negative error code.
> +	 */
> +	if (i < count && of_reserved_mem_device_init_by_idx(dev, of_node, i))
>  		dev_warn(dev, "failed to initialise \"restricted-dma-pool\" memory node\n");

/me shakes fist at of_property_count_elems_of_size()

Thanks for the fix:

Acked-by: Will Deacon <will@xxxxxxxxxx>

Will