linux-kernel - Re: [PATCH] rtlwifi: rtl8192cu: Remove variable self-assignment in rf.c

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Message-ID: <947198f5-23eb-afbc-7979-fbc38b6a1a37@lwfinger.net>
Date:   Wed, 7 Feb 2018 14:35:59 -0600
From:   Larry Finger <Larry.Finger@...inger.net>
To:     Matthias Kaehlcke <mka@...omium.org>,
        Ping-Ke Shih <pkshih@...ltek.com>,
        Kalle Valo <kvalo@...eaurora.org>
Cc:     linux-wireless@...r.kernel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, Guenter Roeck <groeck@...omium.org>,
        Justin TerAvest <teravest@...omium.org>,
        Craig Bergstrom <craigb@...omium.org>
Subject: Re: [PATCH] rtlwifi: rtl8192cu: Remove variable self-assignment in
 rf.c

On 02/07/2018 02:26 PM, Matthias Kaehlcke wrote:
> In _rtl92c_get_txpower_writeval_by_regulatory() the variable writeVal
> is assigned to itself in an if ... else statement, apparently only to
> document that the branch condition is handled and that a previously read
> value should be returned unmodified. The self-assignment causes clang to
> raise the following warning:
> 
> drivers/net/wireless/realtek/rtlwifi/rtl8192cu/rf.c:304:13:
>    error: explicitly assigning value of variable of type 'u32'
>      (aka 'unsigned int') to itself [-Werror,-Wself-assign]
>    writeVal = writeVal;
> 
> Replace the self-assignment with a semicolon, which still serves to
> document the 'handling' of the branch condition.
> 
> Signed-off-by: Matthias Kaehlcke <mka@...omium.org>
> ---
>   drivers/net/wireless/realtek/rtlwifi/rtl8192cu/rf.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/net/wireless/realtek/rtlwifi/rtl8192cu/rf.c b/drivers/net/wireless/realtek/rtlwifi/rtl8192cu/rf.c
> index 9cff6bc4049c..4db92496c122 100644
> --- a/drivers/net/wireless/realtek/rtlwifi/rtl8192cu/rf.c
> +++ b/drivers/net/wireless/realtek/rtlwifi/rtl8192cu/rf.c
> @@ -301,7 +301,7 @@ static void _rtl92c_get_txpower_writeval_by_regulatory(struct ieee80211_hw *hw,
>   			writeVal = writeVal - 0x06060606;
>   		else if (rtlpriv->dm.dynamic_txhighpower_lvl ==
>   			 TXHIGHPWRLEVEL_BT2)
> -			writeVal = writeVal;
> +			;
>   		*(p_outwriteval + rf) = writeVal;
>   	}
>   }
> 

As the branch condition does nothing, why not remove it and save the compiler's 
optimizer a bit of work? The code looks strange, but it matches the rest of 
Realtek's USB drivers.

Larry