Re: [PATCH 1/7] wiphy: fix runtime error from bit shift

From: Denis Kenzior <denkenz@gmail.com>
To: James Prestwood <prestwoj@gmail.com>, iwd@lists.linux.dev
Subject: Re: [PATCH 1/7] wiphy: fix runtime error from bit shift
Date: Fri, 22 Jul 2022 12:04:21 -0500	[thread overview]
Message-ID: <e144ecce-eaad-0156-4f9a-947c0b01b555@gmail.com> (raw)
In-Reply-To: <20220722163417.1119334-1-prestwoj@gmail.com>

Hi James,

On 7/22/22 11:34, James Prestwood wrote:
> The compiler treated the '1' as an int type which was not big enough
> to hold a bit shift of 31. Change this to 1ULL to fix the error:
> 
> runtime error: left shift of 1 by 31 places cannot be represented in type 'int'
> ---
>   src/wiphy.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/src/wiphy.c b/src/wiphy.c
> index 09b99fb2..4b9e130a 100644
> --- a/src/wiphy.c
> +++ b/src/wiphy.c
> @@ -957,7 +957,7 @@ static void wiphy_print_he_capabilities(struct band *band,
>   	uint8_t width_set = bit_field(he_cap->he_phy_capa[0], 1, 7);
>   
>   	for (i = 0; i < 32; i++) {
> -		if (!(he_cap->iftypes & (1 << i)))
> +		if (!(he_cap->iftypes & (1ULL << i)))

That seems overkill, wouldn't 1U be enough?  Or just make 'i' unsigned?

Have you looked into using wiphy_get_supported_iftypes() here instead?

>   			continue;
>   
>   		if (L_WARN_ON(s >= type_buf + sizeof(type_buf)))

Regards,
-Denis