2015-02-24 1:07 GMT+03:00 Johannes Berg <johannes@xxxxxxxxxxxxxxxx>:
> On Mon, 2015-02-23 at 23:01 +0100, Johannes Berg wrote:
>> On Mon, 2015-02-23 at 22:52 +0100, Johannes Berg wrote:
>>
>> > We also can't rely on 4-byte alignment though, so perhaps we should do
>> > something like
>> >
>> > u32 sta_info_hash(void *addr, u32 len, u32 seed)
>> > {
>> > u16 *a = addr;
>> >
>> > return jhash_3words(a[0], a[1], a[2], seed);
>> > }
>>
>> Or better do
>>
>> return jhash_2words(addr[0], (addr[1] << 16) | addr[2], seed);
>>
>> since I have no idea how the missing high 16 bits would behave.
>> (we can rely on 2-byte alignment, but not 4-byte)
>
> Actually, we cannot rely on alignment, so we need to do this:
>
> static u32 sta_addr_hash(const void *key, u32 length, u32 seed)
> {
> return jhash(key, ETH_ALEN, seed);
> }
>
> which still generates better code since the compiler can optimise based
> on the fixed length.
>
Nice catch!
--
Sergey
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