HEADS UP: IFF_NEEDSGIANT consumers to be disabled, removed

[Robert Watson]

On Tue, 17 Feb 2009, Krassimir Slavchev wrote:

>> if_sr and if_ar are really simple and could probably be converted 
>> "trivially".. especially if their netgraph code is used.
>>
>> however I wonder if anyone still has that hardware (they are drivers for 
>> two sync serial cards).
>
> I still have such Digi/Arnet SYNC/570i PCI card and I used to use it for a 
> long time with 4.x and if_ar driver without any problems.
>
> Thanks to John Hay for well written driver!

I would be quite happy to see the remaining drivers be converted over -- when 
using IFF_NEEDSGIANT, they do potentially see a significant performance loss 
as a result of having to defer execution to Giant-holding contexts.  However, 
the sooner the better, as stripping the Giant compat stuff will allow us to 
clean up the compat shims, in turn removing the need for deferred execution to 
avoid calling those shims in unfortunate contexts for multicast, and 
simplifies the forthcoming address list locking work.

Robert N M Watson
Computer Laboratory
University of Cambridge