Re: SCTP config 2.5.70(-bk)

Re: SCTP config 2.5.70(-bk)

[Adrian Bunk]

On Mon, Jun 02, 2003 at 09:53:04AM +0200, Margit Schubert-While wrote:

> CONFIG_IPV6_SCTP__   is always being set to "y" even though
> not selected (CONFIG_IPV6 not set)

First, this doesn't do any harm since CONFIG_IPV6_SCTP__ alone doensn't 
result in anything getting compiled.

But besides, it seems a bit broken.

>From net/sctp/Kconfig:

<--  snip  -->

...

config IPV6_SCTP__
        tristate
        default y if IPV6=n
        default IPV6 if IPV6

config IP_SCTP
        tristate "The SCTP Protocol (EXPERIMENTAL)"
        depends on IPV6_SCTP__
...

<--  snip  -->


Semantically equivalent is the following for IPV6_SCTP__:

config IPV6_SCTP__
        tristate
        default y if IPV6=n || IPV6=y
	default m if IPV6=m


If it was intended to disallow a static IP_SCTP with a modular IPV6 it 
doesn't work: It's perfectly allowed to set IPV6=n and IP_SCTP=y and 
later compile and install a modular IPV6 for the same kernel.


Could someone from the SCTP developers comment on the intentions behind 
IPV6_SCTP__ ?


> Margit

cu
Adrian

-- 

       "Is there not promise of rain?" Ling Tan asked suddenly out
        of the darkness. There had been need of rain for many days.
       "Only a promise," Lao Er said.
                                       Pearl S. Buck - Dragon Seed

Re: [Lksctp-developers] Re: SCTP config 2.5.70(-bk)

[Jon Grimm]

Hi Adrian,

	Sorry for a bit of delay... We are away at an SCTP Interoperability 
event.

Adrian Bunk wrote:
> On Mon, Jun 02, 2003 at 09:53:04AM +0200, Margit Schubert-While wrote:
> 
> 
>>CONFIG_IPV6_SCTP__   is always being set to "y" even though
>>not selected (CONFIG_IPV6 not set)
> 
> 
> First, this doesn't do any harm since CONFIG_IPV6_SCTP__ alone doensn't 
> result in anything getting compiled.
> 
> But besides, it seems a bit broken.
> 
> From net/sctp/Kconfig:
> 
> <--  snip  -->
> 
> ...
> 
> config IPV6_SCTP__
>         tristate
>         default y if IPV6=n
>         default IPV6 if IPV6
> 
> config IP_SCTP
>         tristate "The SCTP Protocol (EXPERIMENTAL)"
>         depends on IPV6_SCTP__
> ...
> 
> <--  snip  -->
> 
> 
> Semantically equivalent is the following for IPV6_SCTP__:
> 
> config IPV6_SCTP__
>         tristate
>         default y if IPV6=n || IPV6=y
> 	default m if IPV6=m
> 
> 
> If it was intended to disallow a static IP_SCTP with a modular IPV6 it 
> doesn't work: It's perfectly allowed to set IPV6=n and IP_SCTP=y and 
> later compile and install a modular IPV6 for the same kernel.
> 

Are you sure?  I vaguely remember one of the network structs having 
#ifdef'd fields for v6.   Consequently, if one compiles first without, 
but the tries later compiles/loads ipv6... bad things happen as the 
kernel has a different concept of what the sock is.

> 
> Could someone from the SCTP developers comment on the intentions behind 
> IPV6_SCTP__ ?
> 

Yes.  The intent was to at least discourage a configuration that will 
segfault.

Thanks,
jon

> 
> 
>>Margit
> 
> 
> cu
> Adrian
> 

Re: [Lksctp-developers] Re: SCTP config 2.5.70(-bk)

[Adrian Bunk]

On Tue, Jun 03, 2003 at 04:07:08PM -0500, Jon Grimm wrote:

> Hi Adrian,

Hi Jon,

> 	Sorry for a bit of delay... We are away at an SCTP Interoperability 
> event.

the delay before my answer was bigger...

> Adrian Bunk wrote:
> >On Mon, Jun 02, 2003 at 09:53:04AM +0200, Margit Schubert-While wrote:
> >
> >
> >>CONFIG_IPV6_SCTP__   is always being set to "y" even though
> >>not selected (CONFIG_IPV6 not set)
> >
> >
> >First, this doesn't do any harm since CONFIG_IPV6_SCTP__ alone doensn't 
> >result in anything getting compiled.
> >
> >But besides, it seems a bit broken.
> >
> >From net/sctp/Kconfig:
> >
> ><--  snip  -->
> >
> >...
> >
> >config IPV6_SCTP__
> >        tristate
> >        default y if IPV6=n
> >        default IPV6 if IPV6
> >
> >config IP_SCTP
> >        tristate "The SCTP Protocol (EXPERIMENTAL)"
> >        depends on IPV6_SCTP__
> >...
> >
> ><--  snip  -->
> >
> >
> >Semantically equivalent is the following for IPV6_SCTP__:
> >
> >config IPV6_SCTP__
> >        tristate
> >        default y if IPV6=n || IPV6=y
> >	default m if IPV6=m
> >
> >
> >If it was intended to disallow a static IP_SCTP with a modular IPV6 it 
> >doesn't work: It's perfectly allowed to set IPV6=n and IP_SCTP=y and 
> >later compile and install a modular IPV6 for the same kernel.
> >
> 
> Are you sure?  I vaguely remember one of the network structs having 
> #ifdef'd fields for v6.   Consequently, if one compiles first without, 
> but the tries later compiles/loads ipv6... bad things happen as the 
> kernel has a different concept of what the sock is.


after reading this at net/Kconfig:

<--  snip  -->

...
#   IPv6 as module will cause a CRASH if you try to unload it
config IPV6
        tristate "The IPv6 protocol (EXPERIMENTAL)"
...

<--  snip  -->

I'm wondering whether it might be an idea to disallow the modular 
building of IPv6 support?


> >Could someone from the SCTP developers comment on the intentions behind 
> >IPV6_SCTP__ ?
> >
> 
> Yes.  The intent was to at least discourage a configuration that will 
> segfault.

It's currently discouraged but not completelyt impossible to select...

> Thanks,
> jon

cu
Adrian

-- 

       "Is there not promise of rain?" Ling Tan asked suddenly out
        of the darkness. There had been need of rain for many days.
       "Only a promise," Lao Er said.
                                       Pearl S. Buck - Dragon Seed