Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Subject: Re: [PATCH] rtlwifi: rtl8192cu: remove pointless memcpy
To:     Arnd Bergmann <arnd@arndb.de>, Ping-Ke Shih <pkshih@realtek.com>
Cc:     Kalle Valo <kvalo@codeaurora.org>,
        Johannes Berg <johannes.berg@intel.com>,
        linux-wireless@vger.kernel.org, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org
References: <20180209132531.2755482-1-arnd@arndb.de>
From:   Larry Finger <Larry.Finger@lwfinger.net>
Message-ID: <22ae9af4-70db-19d7-9b6d-2b0e3dc853d0@lwfinger.net>
Date:   Fri, 9 Feb 2018 10:56:57 -0600
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101
 Thunderbird/52.6.0
MIME-Version: 1.0
In-Reply-To: <20180209132531.2755482-1-arnd@arndb.de>
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Language: en-US
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On 02/09/2018 07:24 AM, Arnd Bergmann wrote:
> gcc-8 points out that source and destination of the memcpy() are
> always the same pointer, so the effect of memcpy() is undefined
> here (its arguments must not overlap):
> 
> drivers/net/wireless/realtek/rtlwifi/rtl8192cu/trx.c: In function '_rtl_rx_process':
> drivers/net/wireless/realtek/rtlwifi/rtl8192cu/trx.c:430:2: error: 'memcpy' source argument is the same as destination [-Werror=restrict]
> 
> Most likely this is harmless, but it's easy to just remove the
> line and get rid of the warning.
> 
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
>   drivers/net/wireless/realtek/rtlwifi/rtl8192cu/trx.c | 1 -
>   1 file changed, 1 deletion(-)
> 
> diff --git a/drivers/net/wireless/realtek/rtlwifi/rtl8192cu/trx.c b/drivers/net/wireless/realtek/rtlwifi/rtl8192cu/trx.c
> index ac4a82de40c7..9ab56827124e 100644
> --- a/drivers/net/wireless/realtek/rtlwifi/rtl8192cu/trx.c
> +++ b/drivers/net/wireless/realtek/rtlwifi/rtl8192cu/trx.c
> @@ -427,7 +427,6 @@ static void _rtl_rx_process(struct ieee80211_hw *hw, struct sk_buff *skb)
>   		 (u32)hdr->addr1[0], (u32)hdr->addr1[1],
>   		 (u32)hdr->addr1[2], (u32)hdr->addr1[3],
>   		 (u32)hdr->addr1[4], (u32)hdr->addr1[5]);
> -	memcpy(IEEE80211_SKB_RXCB(skb), rx_status, sizeof(*rx_status));
>   	ieee80211_rx(hw, skb);
>   }

Argh. Once again I got tripped up on pointers. Yes, this patch is correct.

Acked-by: Larry Finger <Larry.Finger@lwfinger.net>

Sorry about the noise.

Larry