Re: [PATCH] i40e: use ether_addr_equal_64bits

[Jeff Kirsher]

On Fri, 2013-12-27 at 13:56 -0800, Joe Perches wrote:
> All ether_addr_equal tests in i40e can use the
> slightly more efficient ether_addr_equal_64bits.
> 
> All addresses passed to the various functions that
> use ether_addr_equal are using structs that have 2
> or more bytes of additional data after the mac addr
> being tested.
> 
> struct i40e_mac_filter.macaddr[6] (followed by s16 vlan)
> struct net_device.dev_addr (pointer to char array of MAX_ADDR_LEN)
> struct sockaddr.sa_data (array of 14 bytes)
> struct netdev_hw_addr.addr (pointer to char array of MAX_ADDR_LEN)
> 
> Signed-off-by: Joe Perches <joe@xxxxxxxxxxx>

It looks good, but I would like Jesse and Shannon to review it since we
just were talking about a similar patch last week.

I will add the patch to my queue for now, thanks Joe.

> ---
> 
> On Fri, 2013-12-27 at 12:46 -0800, Joe Perches wrote:
> > On Fri, 2013-12-27 at 21:12 +0100, Julia Lawall wrote:
> > > On Fri, 27 Dec 2013, Joe Perches wrote:
> > > 
> > > > On Fri, 2013-12-27 at 07:48 -0800, Eric Dumazet wrote:
> > > > > On Fri, 2013-12-27 at 14:49 +0800, Ding Tianhong wrote:
> > > > > > Use possibly more efficient ether_addr_equal
> > > > > > to instead of memcmp.
> > > > []
> > > > > > diff --git a/drivers/net/plip/plip.c b/drivers/net/plip/plip.c
> > > > []
> > > > > > @@ -549,7 +549,7 @@ static __be16 plip_type_trans(struct sk_buff *skb, struct net_device *dev)
> > > > > >  
> > > > > >  	if(*eth->h_dest&1)
> > > > > >  	{
> > > > > > -		if(memcmp(eth->h_dest,dev->broadcast, ETH_ALEN)==0)
> > > > > > +		if(ether_addr_equal(eth->h_dest, dev->broadcast))
> > > > > >  			skb->pkt_type=PACKET_BROADCAST;
> > > > > >  		else
> > > > > >  			skb->pkt_type=PACKET_MULTICAST;
> > > > > 
> > > > > What about :
> > > > > 
> > > > >         if (is_multicast_ether_addr(eth->h_dest)) {
> > > > >                 if (ether_addr_equal_64bits(eth->h_dest, dev->broadcast))
> > > > >                         skb->pkt_type = PACKET_BROADCAST;
> > > > >                 else
> > > > >                         skb->pkt_type = PACKET_MULTICAST;
> > > > >         }
> > > > 
> > > > That is better though I wonder how many systems are
> > > > still using laplink via parallel null-printer cables.
> > > > 
> > > > No matter, better is better.
> > > > 
> > > > The same optimization using ether_addr_equal_64bits
> > > > may be possible to do in other places given other
> > > > structs too.
> > > > 
> > > > Perhaps it's a possible spatch/coccinelle conversion,
> > > > 
> > > > I don't know spatch well enough to know if a
> > > > mechanism to check if structure members have other
> > > > fields that follow them in the structure or if the
> > > > structure member is an array of a minimum size.
> > > > 
> > > > Maybe Julia does.  (cc'd)
> > > 
> > > I'm not sure to competely understand the issues.  Could you explain more?
> > 
> > Hi Julia.
> > 
> > Maybe this explanation is helpful?
> > 
> > ethernet addresses are u8[6] (48 bits)
> > 
> > ether_addr_equal_64bits gets passed a pointer to u8[8]
> > and is more efficient on 64 bit architectures than
> > ether_addr_equal because the test can be done with a
> > single compare and shift.
> > 
> > The idea is not to access past the end of the ethernet
> > address as appropriate (think pointer to eeprom or other
> > such end-of-addressable memory conditions)
> > 
> > If a struct containing an ethernet address has additional
> > members after the ethernet address, or the u8[6] addressa
> > passed to ether_addr_equal is not going to access past
> > the end of memory or the structure, then
> > ether_addr_equal_64bits should be used in lieu of
> > ether_addr_equal.
> 
> I believe this is correct, but maybe the
> conditions for using ether_addr_equal_64bits
> could be documented a bit better.
> 
> Jeff/Intel folk?  What do you think?
> 
>  drivers/net/ethernet/intel/i40e/i40e_main.c | 18 +++++++++++-------
>  1 file changed, 11 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/net/ethernet/intel/i40e/i40e_main.c b/drivers/net/ethernet/intel/i40e/i40e_main.c
> index efdf8a2..4c1d35c 100644
> --- a/drivers/net/ethernet/intel/i40e/i40e_main.c
> +++ b/drivers/net/ethernet/intel/i40e/i40e_main.c
> @@ -992,7 +992,7 @@ static struct i40e_mac_filter *i40e_find_filter(struct i40e_vsi *vsi,
>  		return NULL;
>  
>  	list_for_each_entry(f, &vsi->mac_filter_list, list) {
> -		if ((ether_addr_equal(macaddr, f->macaddr)) &&
> +		if (ether_addr_equal_64bits(macaddr, f->macaddr) &&
>  		    (vlan == f->vlan)    &&
>  		    (!is_vf || f->is_vf) &&
>  		    (!is_netdev || f->is_netdev))
> @@ -1020,7 +1020,7 @@ struct i40e_mac_filter *i40e_find_mac(struct i40e_vsi *vsi, u8 *macaddr,
>  		return NULL;
>  
>  	list_for_each_entry(f, &vsi->mac_filter_list, list) {
> -		if ((ether_addr_equal(macaddr, f->macaddr)) &&
> +		if (ether_addr_equal_64bits(macaddr, f->macaddr) &&
>  		    (!is_vf || f->is_vf) &&
>  		    (!is_netdev || f->is_netdev))
>  			return f;
> @@ -1209,7 +1209,7 @@ static int i40e_set_mac(struct net_device *netdev, void *p)
>  
>  	netdev_info(netdev, "set mac address=%pM\n", addr->sa_data);
>  
> -	if (ether_addr_equal(netdev->dev_addr, addr->sa_data))
> +	if (ether_addr_equal_64bits(netdev->dev_addr, addr->sa_data))
>  		return 0;
>  
>  	if (vsi->type == I40E_VSI_MAIN) {
> @@ -1409,21 +1409,24 @@ static void i40e_set_rx_mode(struct net_device *netdev)
>  
>  		if (is_multicast_ether_addr(f->macaddr)) {
>  			netdev_for_each_mc_addr(mca, netdev) {
> -				if (ether_addr_equal(mca->addr, f->macaddr)) {
> +				if (ether_addr_equal_64bits(mca->addr,
> +							    f->macaddr)) {
>  					found = true;
>  					break;
>  				}
>  			}
>  		} else {
>  			netdev_for_each_uc_addr(uca, netdev) {
> -				if (ether_addr_equal(uca->addr, f->macaddr)) {
> +				if (ether_addr_equal_64bits(uca->addr,
> +							    f->macaddr)) {
>  					found = true;
>  					break;
>  				}
>  			}
>  
>  			for_each_dev_addr(netdev, ha) {
> -				if (ether_addr_equal(ha->addr, f->macaddr)) {
> +				if (ether_addr_equal_64bits(ha->addr,
> +							    f->macaddr)) {
>  					found = true;
>  					break;
>  				}
> @@ -1889,7 +1892,8 @@ int i40e_vsi_kill_vlan(struct i40e_vsi *vsi, s16 vid)
>  	list_for_each_entry(f, &vsi->mac_filter_list, list) {
>  		if (is_netdev) {
>  			if (f->vlan &&
> -			    ether_addr_equal(netdev->dev_addr, f->macaddr))
> +			    ether_addr_equal_64bits(netdev->dev_addr,
> +						    f->macaddr))
>  				filter_count++;
>  		}
>  
> 
>

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