From: Andrew Lunn <and...@lunn.ch>
Date: Wed, 4 Jan 2017 22:19:57 +0100
> On Wed, Jan 04, 2017 at 04:11:03PM -0500, David Miller wrote:
>> From: Andrew Lunn <and...@lunn.ch>
>> Date: Wed, 4 Jan 2017 19:56:24 +0100
>>
>> > +static inline u64 ether_addr_to_u64(const u8 *addr)
>> > +{
>> > + u64 u = 0;
>> > + int i;
>> > +
>> > + for (i = 0; i < ETH_ALEN; i++)
>> > + u = u << 8 | addr[i];
>> > +
>> > + return u;
>> > +}
>> ...
>> > +static inline void u64_to_ether_addr(u64 u, u8 *addr)
>> > +{
>> > + int i;
>> > +
>> > + for (i = ETH_ALEN - 1; i >= 0; i--) {
>> > + addr[i] = u & 0xff;
>> > + u = u >> 8;
>> > + }
>> > +}
>>
>> I think these two routines behave differently on big vs little
>> endian. And I doubt this was your intention.
>
> I don't have a big endian system to test on.
>
> I tried to avoid the usual pitfalls. I don't cast a collection of
> bytes to a u64, which i know has no chance of working. Accessing a MAC
> address as a byte array should be endian safe. The shift operation
> should also be endian safe.
>
> What exactly do you think will behave differently?
Maybe I over-reacted.
I just ran some test programs in userspace on both little and big
endian and they checked out.
Sorry for the false alarm.
I'll apply this, thanks.
