Re: [PATCH 4/6] arm/duart: make dt_uart_init() compile with -Wwrite-strings

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Mon, 20 Nov 2023, Andrew Cooper wrote:
> GCC complains:
> 
>   drivers/char/arm-uart.c: In function 'dt_uart_init':
>   drivers/char/arm-uart.c:81:17: error: assignment discards 'const' qualifier 
> from pointer target type [-Werror=discarded-qualifiers]
>      81 |         options = "";
>         |                 ^
> 
> The problem is using the options string for both splitting opt_duart, and to
> hold a token "" for no options.
> 
> Use two variables; one mutable one one const.
> 
> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>

Reviewed-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>


> ---
> CC: Stefano Stabellini <sstabellini@xxxxxxxxxx>
> CC: Julien Grall <julien@xxxxxxx>
> CC: Volodymyr Babchuk <Volodymyr_Babchuk@xxxxxxxx>
> CC: Bertrand Marquis <bertrand.marquis@xxxxxxx>
> CC: Michal Orzel <michal.orzel@xxxxxxx>
> CC: Roberto Bagnara <roberto.bagnara@xxxxxxxxxxx>
> CC: Nicola Vetrini <nicola.vetrini@xxxxxxxxxxx>
> ---
>  xen/drivers/char/arm-uart.c | 12 ++++++++----
>  1 file changed, 8 insertions(+), 4 deletions(-)
> 
> diff --git a/xen/drivers/char/arm-uart.c b/xen/drivers/char/arm-uart.c
> index 8098a968c285..91f13a41368d 100644
> --- a/xen/drivers/char/arm-uart.c
> +++ b/xen/drivers/char/arm-uart.c
> @@ -42,7 +42,8 @@ static void __init dt_uart_init(void)
>      struct dt_device_node *dev;
>      int ret;
>      const char *devpath = opt_dtuart;
> -    char *options;
> +    const char *options;
> +    char *split;
>  
>      if ( !console_has("dtuart") )
>          return; /* Not for us */
> @@ -74,9 +75,12 @@ static void __init dt_uart_init(void)
>          return;
>      }
>  
> -    options = strchr(opt_dtuart, ':');
> -    if ( options != NULL )
> -        *(options++) = '\0';
> +    split = strchr(opt_dtuart, ':');
> +    if ( split )
> +    {
> +        split[0] = '\0';
> +        options = split + 1;
> +    }
>      else
>          options = "";
>  
> -- 
> 2.30.2
> 
>