Re: [PATCH v8 16/30] dhcpv6: Use iov_tail in dhcpv6_opt()

[Laurent Vivier <lvivier@redhat.com>]

On 06/08/2025 06:14, David Gibson wrote:
> On Tue, Aug 05, 2025 at 05:46:14PM +0200, Laurent Vivier wrote:
>> dhcpv6_opt() and its callers are refactored for iov_tail option parsing,
>> replacing direct offset management for improved robustness.
>>
>> Its signature is now `bool dhcpv6_opt(iov_tail *data, type)`. `*data` (in/out)
>> points to a found option on `true` return or is restored on `false`.
>> The main dhcpv6() function uses IOV_REMOVE_HEADER for the msg_hdr, then
>> passes the iov_tail (now at options start) to the new dhcpv6_opt().
>>
>> Signed-off-by: Laurent Vivier <lvivier@redhat.com>
> 
> Hmm.  I'm not sure this is a great use case for iov_tail - the code is
> repeatedly scanning the same options, so there's a whole bunch of
> rewinding.  It works, but it seems awkward.
> 
> DHCP is a slow path, anyway, so maybe we'd be better off just
> linearizing the entire packet and using plain old pointers to scan
> through the options.
> 

Well, I'd like to avoid to rewrite this patch as it has a lot of changes.

But if you think it's really needed I will do in a new version of the series.

Thanks,
LAurent