Re: [PATCH v2 net] nfp: cast sizeof() to int when comparing with error code

[Joe Perches]

On Tue, 2018-06-26 at 09:16 +0800, Chengguang Xu wrote:
> sizeof() will return unsigned value so in the error check
> negative error code will be always larger than sizeof().
[]
> diff --git a/drivers/net/ethernet/netronome/nfp/nfpcore/nfp_nffw.c 
> b/drivers/net/ethernet/netronome/nfp/nfpcore/nfp_nffw.c
[]
> @@ -232,7 +232,7 @@ struct nfp_nffw_info *nfp_nffw_info_open(struct nfp_cpp 
> *cpp)
>       err = nfp_cpp_read(cpp, nfp_resource_cpp_id(state->res),
>                          nfp_resource_address(state->res),
>                          fwinf, sizeof(*fwinf));
> -     if (err < sizeof(*fwinf))
> +     if (err < (int)sizeof(*fwinf))
>               goto err_release;
>  
>       if (!nffw_res_flg_init_get(fwinf))

The way this is done in several places in the kernel is
to test first for < 0 and then test for < sizeof

        if (err < 0 || err < sizeof(etc...)

see net/ceph/ceph_common.c etc...