netdev - Re: [PATCH net-next-2.6] etherdevice.h: Add is_unicast_ether

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Message-ID: <1294908916.3570.21.camel@edumazet-laptop>
Date:	Thu, 13 Jan 2011 09:55:16 +0100
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Joe Perches <joe@...ches.com>
Cc:	Tobias Klauser <tklauser@...tanz.ch>,
	David Miller <davem@...emloft.net>, cmetcalf@...era.com,
	netdev@...r.kernel.org
Subject: Re: [PATCH net-next-2.6] etherdevice.h: Add is_unicast_ether_addr
 function

Le jeudi 13 janvier 2011 à 00:24 -0800, Joe Perches a écrit :
> On Thu, 2011-01-13 at 09:14 +0100, Tobias Klauser wrote:
> > >From a check for !is_multicast_ether_addr it is not always obvious that
> > we're checking for a unicast address. So add this helper function to
> > make those code paths easier to read.
> >  include/linux/etherdevice.h |   11 +++++++++++
> []
> >  /**
> > + * is_unicast_ether_addr - Determine if the Ethernet address is unicast
> > + * @addr: Pointer to a six-byte array containing the Ethernet address
> > + *
> > + * Return true if the address is a unicast address.
> > + */
> > +static inline int is_unicast_ether_addr(const u8 *addr)
> > +{
> > +	return !is_multicast_ether_addr(addr);
> > +}
> 
> Can't you simply use is_valid_ether_addr?
> 
> I can't think of much reason that a new function for
> !multicast without the !is_zero is needed.
> 

performance ?

is_valid_ether_addr() is used at device init time, not when receiving
packets.

I am not sure we _need_ to check for is_zero_ether_addr() each time we
receive a packet.

Either a MAC is unicast or multicast.

A zero address is not multicast for sure.



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