linux-kernel - Re: [PATCH 07/14] staging: r8188eu: use memcpy for fallback mac address

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Date:   Tue, 12 Jul 2022 09:28:59 -0700
From:   Joe Perches <joe@...ches.com>
To:     Martin Kaiser <martin@...ser.cx>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Larry Finger <Larry.Finger@...inger.net>,
        Phillip Potter <phil@...lpotter.co.uk>,
        Michael Straube <straube.linux@...il.com>,
        Pavel Skripkin <paskripkin@...il.com>,
        linux-staging@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 07/14] staging: r8188eu: use memcpy for fallback mac
 address

On Sat, 2022-07-09 at 19:09 +0200, Martin Kaiser wrote:
> Use memcpy to store the fallback mac address in eeprom->mac_addr. Do not
> copy byte by byte.
[]
> diff --git a/drivers/staging/r8188eu/hal/usb_halinit.c b/drivers/staging/r8188eu/hal/usb_halinit.c
[]
> @@ -912,13 +912,11 @@ unsigned int rtl8188eu_inirp_init(struct adapter *Adapter)
>  
>  static void Hal_EfuseParseMACAddr_8188EU(struct adapter *adapt, u8 *hwinfo, bool AutoLoadFail)
>  {
> -	u16 i;
>  	u8 sMacAddr[6] = {0x00, 0xE0, 0x4C, 0x81, 0x88, 0x02};

static const sMacAddr[ETH_ALEN] = {...};

But maybe this should use eth_random_addr instead as there might
be more than one of these in a network.

>  	struct eeprom_priv *eeprom = &adapt->eeprompriv;
>  
>  	if (AutoLoadFail) {
> -		for (i = 0; i < 6; i++)
> -			eeprom->mac_addr[i] = sMacAddr[i];
> +		memcpy(eeprom->mac_addr, sMacAddr, ETH_ALEN);
>  	} else {
>  		/* Read Permanent MAC address */
>  		memcpy(eeprom->mac_addr, &hwinfo[EEPROM_MAC_ADDR_88EU], ETH_ALEN);

So perhaps something like:

{
	static const u8 sMacAddr[ETH_ALEN] = {
		0x00, 0xE0, 0x4C, 0x81, 0x88, 0x02
	};

	/* Not ether_addr_copy - EEPROM_MAC_ADDR_88EU isn't __aligned(2) */

	memcpy(adapt->eeprompriv.mac_addr,
	       AutoLoadFail ? sMacAddr : &hwinfo[EEPROM_MAC_ADDR_88EU],
	       ETH_ALEN);
}

or maybe:

{
	if (AutoLoadFail)
		eth_random_addr(adapt->eeprompriv.mac_addr);
	else
		memcpy(adapt->eeprompriv.mac_addr,
		       &hwinfo[EEPROM_MAC_ADDR_88EU], ETH_ALEN);