linux-kernel - Re: [PATCH] staging: wlan-ng: Fix sparse warning: cast to restricted _

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Date:   Fri, 18 Aug 2017 19:49:56 +0100
From:   Ricardo Silva <rjpdasilva@...il.com>
To:     AbdAllah-MEZITI <abdallah.meziti.pro@...il.com>,
        gregkh@...uxfoundation.org
Cc:     devel@...verdev.osuosl.org,
        Thibaut SAUTEREAU <thibaut.sautereau@...ecom-sudparis.eu>,
        Juliana Rodrigues <juliana.orod@...il.com>,
        sayli karnik <karniksayli1995@...il.com>,
        linux-kernel@...r.kernel.org,
        Sergio Paracuellos <sergio.paracuellos@...il.com>,
        Jannik Becher <becher.jannik@...il.com>
Subject: Re: [PATCH] staging: wlan-ng: Fix sparse warning: cast to restricted
 __le16.

Hi,

On 08/09/2017 11:35 PM, AbdAllah-MEZITI wrote:
> The same structure is used in both side, so we dont need to cast.

I believe there were no casts there, but calls to le16_to_cpu(),
meaning there was previously a bug or the data being accessed was
really stored in little-endian format, so we shouldn't just remove
them for silencing sparse.

> This will fix the following sparse warnings:
> drivers/staging/wlan-ng/prism2sta.c:1139:13: warning: cast to restricted __le16
> drivers/staging/wlan-ng/prism2sta.c:1150:24: warning: cast to restricted __le16
> drivers/staging/wlan-ng/prism2sta.c:1157:37: warning: cast to restricted __le16
> drivers/staging/wlan-ng/prism2sta.c:1158:37: warning: cast to restricted __le16
> drivers/staging/wlan-ng/prism2sta.c:1159:40: warning: cast to restricted __le16
> drivers/staging/wlan-ng/prism2sta.c:1450:31: warning: cast to restricted __le16
> 
> Signed-off-by: AbdAllah MEZITI <abdallah.meziti.pro@...il.com>
> ---
>  drivers/staging/wlan-ng/prism2sta.c | 12 ++++++------
>  1 file changed, 6 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/staging/wlan-ng/prism2sta.c b/drivers/staging/wlan-ng/prism2sta.c
> index 8c34712..c9df450 100644
> --- a/drivers/staging/wlan-ng/prism2sta.c
> +++ b/drivers/staging/wlan-ng/prism2sta.c
> @@ -1136,7 +1136,7 @@ static void prism2sta_inf_chinforesults(struct wlandevice *wlandev,
>  	unsigned int i, n;
>  
>  	hw->channel_info.results.scanchannels =
> -	    le16_to_cpu(inf->info.chinforesult.scanchannels);
> +	    inf->info.chinforesult.scanchannels;

If this is not fixing some issue, then I believe it can be introducing
one on big-endian CPUs, right?

>  
>  	for (i = 0, n = 0; i < HFA384x_CHINFORESULT_MAX; i++) {
>  		struct hfa384x_ch_info_result_sub *result;
> @@ -1147,16 +1147,16 @@ static void prism2sta_inf_chinforesults(struct wlandevice *wlandev,
>  			continue;
>  
>  		result = &inf->info.chinforesult.result[n];
> -		chan = le16_to_cpu(result->chid) - 1;
> +		chan = result->chid - 1;

Ditto.

>  
>  		if (chan < 0 || chan >= HFA384x_CHINFORESULT_MAX)
>  			continue;
>  
>  		chinforesult = &hw->channel_info.results.result[chan];
>  		chinforesult->chid = chan;
> -		chinforesult->anl = le16_to_cpu(result->anl);
> -		chinforesult->pnl = le16_to_cpu(result->pnl);
> -		chinforesult->active = le16_to_cpu(result->active);
> +		chinforesult->anl = result->anl;
> +		chinforesult->pnl = result->pnl;
> +		chinforesult->active = result->active;

Ditto.

>  
>  		pr_debug("chinfo: channel %d, %s level (avg/peak)=%d/%d dB, pcf %d\n",
>  			 chan + 1,
> @@ -1447,7 +1447,7 @@ static void prism2sta_inf_linkstatus(struct wlandevice *wlandev,
>  {
>  	struct hfa384x *hw = wlandev->priv;
>  
> -	hw->link_status_new = le16_to_cpu(inf->info.linkstatus.linkstatus);
> +	hw->link_status_new = inf->info.linkstatus.linkstatus;

Ditto.
If I'm wrong about this being incorrect, then I have a patch submitted for fixing
the sparse warning here that should be discarded. My patch is:

  staging: wlan-ng: hfa384x.h: Use endian type in 'hfa384x_link_status'

and changes the linkstatus field to le16.

Regards,

Ricardo Silva

>  
>  	schedule_work(&hw->link_bh);
>  }
>