Re: [PATCH net-next] net:drivers/net: Miscellaneous conversions to ETH_ALEN

[Joe Perches <joe@perches.com>]

On Wed, 2013-10-02 at 10:44 -0700, Luis R. Rodriguez wrote:
> On Tue, Oct 1, 2013 at 11:40 PM, Joe Perches <joe@perches.com> wrote:
> > Please include netdev.  (cc'd)
> >
> >> Joe Perches <joe@perches.com> writes:
> >>
> >> > Convert the memset/memcpy uses of 6 to ETH_ALEN
> >> > where appropriate.
> >
> >> > Signed-off-by: Joe Perches <joe@perches.com>
> 
> I think these sorts of patches are good -- but once applied it'd be
> good if we can get the SmPL grammar expressed for it and then have
> developers / maintainers regularly doing:
> 
> make coccicheck MODE=patch M=path > path-cocci.patch
> 
> Unfortunately right now MODE=patch takes about 3 1/2 minutes for
> ath9k, MODE=org takes ~10 minutes for ath9k (17 minutes for all of
> ath/), and MODE=context takes ~8 minutes on ath9k -- I do believe its
> a bit unreasonable to expect patch submitters to use this, but
> certainly great practice. Some of the time differences on the reports
> can be explained by the fact that some SmPL will only be used for some
> modes.
> 
> Even though it takes a while right now it'd be great practice to use
> coccicheck to prevent these type of changes from going in again,
> things that checkpatch.pl won't be able to catch.

As far as I can tell, it's basically not possible for cocci to
do this conversion.

There are other memcpy/memset uses with size_t = 6 where it's
not a MAC address being copied.

The call site has to be inspected to determine if the copied
to address is used as a MAC address or not.

Maybe if there was some typedef like:

typedef u8 eth_addr_t[ETH_ALEN];

There are a few of these already in use:

$ git grep "typedef.*\[" | grep -P "\[\s*(?:ETH_ALEN|6)\s*\]"
drivers/net/ethernet/broadcom/bnx2x/bnx2x_sriov.h:typedef u8 bnx2x_mac_addr_t[ETH_ALEN];
drivers/net/ethernet/brocade/bna/cna.h:typedef struct mac { u8 mac[ETH_ALEN]; } mac_t;
drivers/net/ethernet/via/via-velocity.h:typedef u8 MCAM_ADDR[ETH_ALEN];
drivers/net/usb/kaweth.c:typedef __u8 eth_addr_t[6];
drivers/net/wireless/ray_cs.c:typedef u_char mac_addr[ETH_ALEN];	/* Hardware address */
drivers/staging/vt6655/wmgr.h:typedef unsigned char NDIS_802_11_MAC_ADDRESS[6];
drivers/staging/vt6656/wmgr.h:typedef u8 NDIS_802_11_MAC_ADDRESS[ETH_ALEN];