linux-kernel - Re: [PATCH] lib80211: remove unused variables iv32 and iv16

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Message-ID: <1dc009dc5c6394640fae1200624e7ba4c706c9b4.camel@sipsolutions.net>
Date:   Mon, 05 Jun 2023 13:59:55 +0200
From:   Johannes Berg <johannes@...solutions.net>
To:     Tom Rix <trix@...hat.com>, davem@...emloft.net,
        edumazet@...gle.com, kuba@...nel.org, pabeni@...hat.com,
        nathan@...nel.org, ndesaulniers@...gle.com
Cc:     linux-wireless@...r.kernel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, llvm@...ts.linux.dev
Subject: Re: [PATCH] lib80211: remove unused variables iv32 and iv16

On Wed, 2023-05-17 at 08:33 -0400, Tom Rix wrote:
> clang with W=1 reports
> net/wireless/lib80211_crypt_tkip.c:667:7: error: variable 'iv32'
>   set but not used [-Werror,-Wunused-but-set-variable]
>                 u32 iv32 = tkey->tx_iv32;
>                     ^
> This variable not used so remove it.
> Then remove a similar iv16 variable.
> Remove the comment because the length is returned.
> 
> Signed-off-by: Tom Rix <trix@...hat.com>
> ---
>  net/wireless/lib80211_crypt_tkip.c | 6 ------
>  1 file changed, 6 deletions(-)
> 
> diff --git a/net/wireless/lib80211_crypt_tkip.c b/net/wireless/lib80211_crypt_tkip.c
> index 1b4d6c87a5c5..9b411b6a7b5d 100644
> --- a/net/wireless/lib80211_crypt_tkip.c
> +++ b/net/wireless/lib80211_crypt_tkip.c
> @@ -662,12 +662,6 @@ static int lib80211_tkip_get_key(void *key, int len, u8 * seq, void *priv)
>  	memcpy(key, tkey->key, TKIP_KEY_LEN);
>  
>  	if (seq) {
> -		/* Return the sequence number of the last transmitted frame. */
> -		u16 iv16 = tkey->tx_iv16;
> -		u32 iv32 = tkey->tx_iv32;
> -		if (iv16 == 0)
> -			iv32--;
> -		iv16--;
> 

FWIW, this has come up before, and we weren't sure that this really is
right and shouldn't have reported the iv32/iv16 values out to userspace
...

That said, it's unlikely anyone would ever go and test his code again,
so I guess we might as well clean this up to get rid of the warning.

Maybe leave a comment?

johannes