Oct 11 2014

staging: vt6655: dpc.c: replace memcpy() by ether_addr_copy() using coccinelle 

Author: Aya Mahfouz <mahfouz.saif.elyazal@gmail.com>

This patch focuses on fixing the following warning generated
by checkpatch.pl for the file dpc.c :

Prefer ether_addr_copy() over memcpy() if the Ethernet addresses
are __aligned(2)

The changes were applied using the following coccinelle rule:

@@ expression e1, e2; @@

- memcpy(e1, e2, ETH_ALEN);
+ ether_addr_copy(e1, e2);

According to ether_addr_copy() description and functionality,
all Ethernet addresses should align to the u16 datatype.

Here is the output of pahole for the relevant datastructures:

struct tagS802_11Header {
        short unsigned int         wFrameCtl;            /*     0     2 */
        short unsigned int         wDurationID;          /*     2     2 */
        unsigned char              abyAddr1[6];          /*     4     6 */
        unsigned char              abyAddr2[6];          /*    10     6 */
        unsigned char              abyAddr3[6];          /*    16     6 */
        short unsigned int         wSeqCtl;              /*    22     2 */
        unsigned char              abyAddr4[6];          /*    24     6 */

        /* size: 30, cachelines: 1, members: 7 */
        /* last cacheline: 30 bytes */
};
struct iw_michaelmicfailure {
        __u32                      flags;                /*     0     4 */
        struct sockaddr            src_addr;             /*     4    16 */
        __u8                       tsc[8];               /*    20     8 */

        /* size: 28, cachelines: 1, members: 3 */
        /* last cacheline: 28 bytes */
};
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 */
};

There is one thing to note though, sa_data is a char array of size 14.
And the number of bytes copied using memcpy() or ether_addr_copy()
is 6.

Signed-off-by: Aya Mahfouz 
Signed-off-by: Greg Kroah-Hartman 

---
 drivers/staging/vt6655/dpc.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
 
diff --git a/drivers/staging/vt6655/dpc.c b/drivers/staging/vt6655/dpc.c
index 8515b8c..344e12f 100644
--- a/drivers/staging/vt6655/dpc.c
+++ b/drivers/staging/vt6655/dpc.c
@@ -742,7 +742,8 @@ device_receive_frame(
 					}
 
 					ev.src_addr.sa_family = ARPHRD_ETHER;
-					memcpy(ev.src_addr.sa_data, pMACHeader->abyAddr2, ETH_ALEN);
+					ether_addr_copy(ev.src_addr.sa_data,
+							pMACHeader->abyAddr2);
 					memset(&wrqu, 0, sizeof(wrqu));
 					wrqu.data.length = sizeof(ev);
 					wireless_send_event(pDevice->dev, IWEVMICHAELMICFAILURE, &wrqu, (char *)&ev);

qlambert