Re: [Xen-devel] [PATCH for-4.12] dt: fix integer check in dt_device_is_compatible

[Julien Grall <julien.grall@xxxxxxx>]

Hi Stefano,

On 11/12/2018 18:46, Stefano Stabellini wrote:
> cplen is unsigned, thus, it can never be < 0. Use a signed integer local
> variable instead.
The current code checks > 0. Looking at the code I don't think it can ever be 
negative. So can you details what is the problem you are trying to resolve?
Cheers,

> Signed-off-by: Stefano Stabellini <stefanos@xxxxxxxxxx>
> ---
>   xen/common/device_tree.c | 7 +++++--
>   1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/xen/common/device_tree.c b/xen/common/device_tree.c
> index 8fc401d..df274cc 100644
> --- a/xen/common/device_tree.c
> +++ b/xen/common/device_tree.c
> @@ -213,17 +213,20 @@ bool_t dt_device_is_compatible(const struct 
> dt_device_node *device,
>   {
>       const char* cp;
>       u32 cplen, l;
> +    s64 ilen;
>   
>       cp = dt_get_property(device, "compatible", &cplen);
>       if ( cp == NULL )
>           return 0;
> -    while ( cplen > 0 )
> +
> +    ilen = cplen;
> +    while ( ilen > 0 )
>       {
>           if ( dt_compat_cmp(cp, compat) == 0 )
>               return 1;
>           l = strlen(cp) + 1;
>           cp += l;
> -        cplen -= l;
> +        ilen -= l;
>       }
>   
>       return 0;
--
Julien Grall

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