[v2,1/1] ARM: orion5x: use mac_pton() helper

[Stefan Hellermann]

2018-02-23 16:51 GMT+01:00 Andrew Lunn <andrew at lunn.ch>:
>> > Hi Andy
>> >
>> > Thanks for pointing this patch out.
>> >
>> > What is the advantage of doing to the strnlen()? As Stefan says, the
>> > code which follows will detect a short string, in that a NULL is not
>> > in [0-9a-f], nor a : .
>>
>> I'm not sure, but my understanding is that, the strchr() call in the
>> original code or isxdigit() in the follow up change will trash a cache a
>> bit. Besides that some of the users are (often?) supplying empty strings
>> to convert from, and in this case makes sense to bail out fast.
>
> Is this function being called on a hot path? In the case which is
> crashing, it is during early boot, and it gets called ~ 40 times, in
> quick succession. The first call to isxdigit() will need to fetch part
> of the _ctype array into cache, but since the caller is only walking
> memory, i hope it is still in cache for the next call to mac_pton().
>
>         Andrew

In my case mac_pton is not called on a hot path, the slow sata disks
in the NAS dominate the boot time. For me code size matters, and on my
device it's rarely called on a zero string. It's probably slower with
the strnlen as without it. I think if there are users out there
calling it in a hot path on a zero string, they should check the zero
string themselves, this is not the common use case.

Should I send a patch to netdev, can I get some Acked-by: ?

    Stefan