Re: [PATCH v2 1/3] iptables: change 'iface' part in hash:net,iface set

[Mr Dash Four <mr.dash.four@googlemail.com>]

> A userspace match/target "works" with the corresponding kernel 
> match/target only when their revision numbers match. The new revisions are 
> our standard way to introduce new features in matches/targets so that it 
> won't break anything and work fine in any old-new kernel-iptables 
> combinations: the system uses (falls back to) the highest revision which 
> is avaliable at both sides.
>
> The new match/target revision in userspace just need the new 
> parse/print/save functions, the matching new match/target revision in 
> kernel space differ from the current one just in revision number.
>   
All noted and tested - that is exactly how it works. Thanks.

>> Similarly, if I rename the new functions to something else, won't that 
>> cause compatibility issues where other programs are going to look for 
>> these functions (from what I remember these functions are defined in the 
>> C header files, so, potentially, after this change they are bound to 
>> break something!). Could you elaborate a bit more please?
>>     
>
> These functions are static. Nothing else uses them.
>   
OK, that's good because I intend to change the parse_dirs function in 
the new "version" and introduce additional parameter called "features" 
so that these are used directly and not rely on the info->flags to store 
these (as was the case up until now). That would also allow for 
additional features to be added in the future, if needed (u8 is almost 
exhausted - you have one spare bit left there!).

> Let there be long spaces, I'll fix those. But with so long lines, it's 
> hard to see the changes.
>   
Noted, will do.

> The header files in include/linux/netfilter in the iptables source are 
> usually not maintained manually. They are generated from the kernel header 
> files by filtering out the kernel specific parts protected by the ifdefs.
>
> At the moment, the enum ip_set_feature definition is kernel specific in 
> the kernel header file. Next time Pablo regenerates the header files for 
> iptables from the kernel ones, your modification above will be lost. 
> Therefore the enum definition must be moved out from the "#ifdef 
> __KERNEL__" region in the kernel header file.
>   
Yep, just saw that too, so I'll just move the ip_set_feature enum just 
above the #ifdef __KERNEL__ part and I assume it would be picked up 
"automatically", is that right?