From mboxrd@z Thu Jan  1 00:00:00 1970
From: David Miller <davem@davemloft.net>
Subject: Re: [PATCH] net: usb: hso: use swap macro in hso_kick_transmit
Date: Wed, 11 Jul 2018 22:58:21 -0700 (PDT)
Message-ID: <20180711.225821.1348569242901912298.davem@davemloft.net>
References: <20180709154048.GA32345@embeddedor.com>
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Cc: linux-usb@vger.kernel.org, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org
To: gustavo@embeddedor.com
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From: "Gustavo A. R. Silva" <gustavo@embeddedor.com>
Date: Mon, 9 Jul 2018 10:40:48 -0500

> @@ -1748,14 +1747,11 @@ static void hso_kick_transmit(struct hso_serial *serial)
>  		goto out;
>  
>  	/* Switch pointers around to avoid memcpy */
> -	temp = serial->tx_buffer;
> -	serial->tx_buffer = serial->tx_data;
> -	serial->tx_data = temp;
> +	swap(serial->tx_buffer, serial->tx_data);
>  	serial->tx_data_count = serial->tx_buffer_count;
>  	serial->tx_buffer_count = 0;
>  
> -	/* If temp is set, it means we switched buffers */
> -	if (temp && serial->write_data) {
> +	if (serial->write_data) {

I think temp can be NULL here, you have to retain this check.