[PATCH v2] staging: rtl8712: Use ether_addr_copy() instead of memcpy()

[PATCH v2] staging: rtl8712: Use ether_addr_copy() instead of memcpy()

[Jagan Teki]

Fixes Warning encounter this by applying checkpatch.pl against this file:
Prefer ether_addr_copy() over memcpy() if the Ethernet addresses
are __aligned(2)

pahole output for respective structures:
- addr->sa_data
struct sockaddr {
	sa_family_t                sa_family;            /*     0     2 */
	char                       sa_data[14];          /*     2    14 */

	/* size: 16, cachelines: 1, members: 2 */
	/* last cacheline: 16 bytes */
};

- padapter->eeprompriv.mac_addr
struct _adapter {
	struct dvobj_priv          dvobjpriv;            /*     0    40 */
	struct mlme_priv           mlmepriv;             /*    40  1560 */
	/* --- cacheline 25 boundary (1600 bytes) --- */
	struct cmd_priv            cmdpriv;              /*  1600   136 */
	/* --- cacheline 27 boundary (1728 bytes) was 8 bytes ago --- */
	struct evt_priv            evtpriv;              /*  1736    96 */
	/* --- cacheline 28 boundary (1792 bytes) was 40 bytes ago --- */
	struct io_queue *          pio_queue;            /*  1832     8 */
	struct xmit_priv           xmitpriv;             /*  1840   912 */
	/* --- cacheline 43 boundary (2752 bytes) --- */
	struct recv_priv           recvpriv;             /*  2752  1088 */
	/* --- cacheline 60 boundary (3840 bytes) --- */
	struct sta_priv            stapriv;              /*  3840   672 */
	/* --- cacheline 70 boundary (4480 bytes) was 32 bytes ago --- */
	struct security_priv       securitypriv;         /*  4512  4816 */
	/* --- cacheline 145 boundary (9280 bytes) was 48 bytes ago --- */
	struct registry_priv       registrypriv;         /*  9328   968 */
	/* --- cacheline 160 boundary (10240 bytes) was 56 bytes ago --- */
	struct wlan_acl_pool       acl_list;             /* 10296  1536 */
	/* --- cacheline 184 boundary (11776 bytes) was 56 bytes ago --- */
	struct pwrctrl_priv        pwrctrlpriv;          /* 11832   224 */
	/* --- cacheline 188 boundary (12032 bytes) was 24 bytes ago --- */
	struct eeprom_priv         eeprompriv;           /* 12056   508 */
	........
};

struct eeprom_priv {
	u8                         bautoload_fail_flag;  /*     0     1 */
	u8                         bempty;               /*     1     1 */
	u8                         sys_config;           /*     2     1 */
	u8                         mac_addr[6];          /*     3     6 */
        ......
};

- pnetdev->dev_addr
dev_addr is interface address infor from generic net_device structure
which is properly aligned and have some patches with this change as well.
"staging: rtl8712: fix Prefer ether_addr_copy() over memcpy()"
(sha1: 36e4d8826b317080e283e4edd08bf8d5ac706f38)

Signed-off-by: Jagan Teki <jteki@openedev.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Larry Finger <Larry.Finger@lwfinger.net>
Cc: Florian Schilhabel <florian.c.schilhabel@googlemail.com>
---
Changes for v2:
	- Describe a changelog, to prove address are aligned.

 drivers/staging/rtl8712/os_intfs.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/staging/rtl8712/os_intfs.c b/drivers/staging/rtl8712/os_intfs.c
index 6e776e5..0d27df6 100644
--- a/drivers/staging/rtl8712/os_intfs.c
+++ b/drivers/staging/rtl8712/os_intfs.c
@@ -181,7 +181,7 @@ static int r871x_net_set_mac_address(struct net_device *pnetdev, void *p)
 	struct sockaddr *addr = p;
 
 	if (padapter->bup == false)
-		memcpy(pnetdev->dev_addr, addr->sa_data, ETH_ALEN);
+		ether_addr_copy(pnetdev->dev_addr, addr->sa_data);
 	return 0;
 }
 
@@ -395,8 +395,8 @@ static int netdev_open(struct net_device *pnetdev)
 			goto netdev_open_error;
 		if (r8712_initmac == NULL)
 			/* Use the mac address stored in the Efuse */
-			memcpy(pnetdev->dev_addr,
-				padapter->eeprompriv.mac_addr, ETH_ALEN);
+			ether_addr_copy(pnetdev->dev_addr,
+					padapter->eeprompriv.mac_addr);
 		else {
 			/* We have to inform f/w to use user-supplied MAC
 			 * address.
@@ -412,8 +412,8 @@ static int netdev_open(struct net_device *pnetdev)
 			 * the eeprompriv.mac_addr should store the mac which
 			 * users specify.
 			 */
-			memcpy(padapter->eeprompriv.mac_addr,
-				pnetdev->dev_addr, ETH_ALEN);
+			ether_addr_copy(padapter->eeprompriv.mac_addr,
+					pnetdev->dev_addr);
 		}
 		if (start_drv_threads(padapter) != _SUCCESS)
 			goto netdev_open_error;
-- 
1.9.1

Re: [PATCH v2] staging: rtl8712: Use ether_addr_copy() instead of memcpy()

[Dan Carpenter]

On Mon, May 18, 2015 at 07:47:06PM +0530, Jagan Teki wrote:
> struct eeprom_priv {
> 	u8                         bautoload_fail_flag;  /*     0     1 */
> 	u8                         bempty;               /*     1     1 */
> 	u8                         sys_config;           /*     2     1 */
> 	u8                         mac_addr[6];          /*     3     6 */
>         ......
> };

This means it's not aligned as we want.

regards,
dan carpenter

Re: [PATCH v2] staging: rtl8712: Use ether_addr_copy() instead of memcpy()

[Jagan Teki]

On 18 May 2015 at 20:08, Dan Carpenter <dan.carpenter@oracle.com> wrote:
> On Mon, May 18, 2015 at 07:47:06PM +0530, Jagan Teki wrote:
>> struct eeprom_priv {
>>       u8                         bautoload_fail_flag;  /*     0     1 */
>>       u8                         bempty;               /*     1     1 */
>>       u8                         sys_config;           /*     2     1 */
>>       u8                         mac_addr[6];          /*     3     6 */
>>         ......
>> };
>
> This means it's not aligned as we want.

Why size upto mac_addr is 9 and is not divisible by 2 is it?

or the mac_addr size is 6 which is divisible by 2 (__align(2))

this is full pahole:

struct eeprom_priv {
u8                         bautoload_fail_flag;  /*     0     1 */
u8                         bempty;               /*     1     1 */
u8                         sys_config;           /*     2     1 */
u8                         mac_addr[6];          /*     3     6 */
u8                         config0;              /*     9     1 */
u16                        channel_plan;         /*    10     2 */
u8                         country_string[3];    /*    12     3 */
u8                         tx_power_b[15];       /*    15    15 */
u8                         tx_power_g[15];       /*    30    15 */
u8                         tx_power_a[201];      /*    45   201 */
/* --- cacheline 3 boundary (192 bytes) was 54 bytes ago --- */
u8                         efuse_eeprom_data[256]; /*   246   256 */

/* XXX 2 bytes hole, try to pack */

/* --- cacheline 7 boundary (448 bytes) was 56 bytes ago --- */
enum RT_CUSTOMER_ID        CustomerID;           /*   504     4 */

/* size: 508, cachelines: 8, members: 12 */
/* sum members: 506, holes: 1, sum holes: 2 */
/* last cacheline: 60 bytes */
};

thanks!
-- 
Jagan Teki,
Openedev.

Re: [PATCH v2] staging: rtl8712: Use ether_addr_copy() instead of memcpy()

[Dan Carpenter]

#include <stdio.h>

struct foo {
	unsigned char one;
	unsigned char two;
	unsigned char three;
	unsigned char mac_addr[6];
	unsigned short channel_plan;
};

int main(void)
{
	struct foo *p = NULL;

	printf("%x\n", &p->mac_addr);

	return 0;
}

This program does not print an even number so the alignment is off.

regards,
dan carpenter