[U-Boot] [PATCH] w1: fix data abort if no one wire bus master present

[Eugen.Hristev at microchip.com]

On 22.10.2018 19:31, Martin Fuzzey wrote:
> When the "w1 bus" command is used with no bus master present
> a data abort may occur.
> 
> This is because uclass_first_device() returns zero, but sets the output
> struct udevice pointer to NULL in the no device found case.
> 
> Fix w1_get_bus() to account for this and return an error code
> as is expected by the callers.
> 
> Signed-off-by: Martin Fuzzey <martin.fuzzey at flowbird.group>
> ---
>   drivers/w1/w1-uclass.c | 14 ++++++++------
>   1 file changed, 8 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/w1/w1-uclass.c b/drivers/w1/w1-uclass.c
> index aecf7fe..cb41b68 100644
> --- a/drivers/w1/w1-uclass.c
> +++ b/drivers/w1/w1-uclass.c
> @@ -115,17 +115,19 @@ int w1_get_bus(int busnum, struct udevice **busp)
>   	struct udevice *dev;
>   
>   	for (ret = uclass_first_device(UCLASS_W1, &dev);
> -	     !ret;
> -	     uclass_next_device(&dev), i++) {
> -		if (ret) {
> -			debug("Cannot find w1 bus %d\n", busnum);
> -			return ret;
> -		}
> +	     dev && !ret;
> +	     ret = uclass_next_device(&dev), i++) {
>   		if (i == busnum) {
>   			*busp = dev;
>   			return 0;
>   		}
>   	}
> +
> +	if (!ret) {

Hi Martin,

Does this mean that if ret != 0 , we had errors, but we are not printing 
this debug message ? Perhaps we should print out here the debug error 
regardless of the ret value ? Since we exited with a return 0 if we did 
find the proper bus.


May I also ask on which board setup you tested this ? And which defconfig.

Thanks,
Eugen

> +		debug("Cannot find w1 bus %d\n", busnum);
> +		ret = -ENODEV;
> +	}
> +
>   	return ret;
>   }
>   
>