Re: [PATCH net-next 1/8] mpls: Refactor how the mpls module is built

[Simon Horman <horms@verge.net.au>]

On Wed, Feb 25, 2015 at 08:15:43PM -0600, Eric W. Biederman wrote:
> Simon Horman <horms@verge.net.au> writes:
> 
> > On Wed, Feb 25, 2015 at 11:13:02AM -0600, Eric W. Biederman wrote:
> >> 
> >> This refactoring is needed to allow more than just mpls gso support to
> >> be built into the mpls moddule.
> >> 
> >> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
> >> ---
> >>  net/Makefile     |  2 +-
> >>  net/mpls/Kconfig | 18 +++++++++++++++++-
> >>  2 files changed, 18 insertions(+), 2 deletions(-)
> >> 
> >> diff --git a/net/Makefile b/net/Makefile
> >> index 38704bdf941a..3995613e5510 100644
> >> --- a/net/Makefile
> >> +++ b/net/Makefile
> >> @@ -69,7 +69,7 @@ obj-$(CONFIG_BATMAN_ADV)	+= batman-adv/
> >>  obj-$(CONFIG_NFC)		+= nfc/
> >>  obj-$(CONFIG_OPENVSWITCH)	+= openvswitch/
> >>  obj-$(CONFIG_VSOCKETS)	+= vmw_vsock/
> >> -obj-$(CONFIG_NET_MPLS_GSO)	+= mpls/
> >> +obj-$(CONFIG_MPLS)		+= mpls/
> >>  obj-$(CONFIG_HSR)		+= hsr/
> >>  ifneq ($(CONFIG_NET_SWITCHDEV),)
> >>  obj-y				+= switchdev/
> >> diff --git a/net/mpls/Kconfig b/net/mpls/Kconfig
> >> index 37421db88965..a77fbcdd04ee 100644
> >> --- a/net/mpls/Kconfig
> >> +++ b/net/mpls/Kconfig
> >> @@ -1,9 +1,25 @@
> >>  #
> >>  # MPLS configuration
> >>  #
> >> +
> >> +menuconfig MPLS
> >> +	tristate "MultiProtocol Label Switching"
> >> +	default n
> >> +	---help---
> >> +	  MultiProtocol Label Switching routes packets through logical
> >> +	  circuits.  Originally conceved as a way of routing packets at
> >> +	  hardware speeds (before hardware was capable of routing ipv4 packets),
> >> +	  MPLS remains as simple way of making tunnels.
> >> +
> >> +	  If you have not heard of MPLS you probably want to say N here.
> >> +
> >> +if MPLS
> >> +
> >>  config NET_MPLS_GSO
> >> -	tristate "MPLS: GSO support"
> >> +	bool "MPLS: GSO support"
> >>  	help
> >>  	 This is helper module to allow segmentation of non-MPLS GSO packets
> >>  	 that have had MPLS stack entries pushed onto them and thus
> >>  	 become MPLS GSO packets.
> >> +
> >> +endif # MPLS
> >
> > Is the implication here that MPLS must be selected to allow NET_MPLS_GSO to
> > be selected? That is if NET_MPLS_GSO is to be used to handle MPLS packets
> > emitted by OVS then now MPLS also needs to be selected?
> 
> Yes.
> 
> That is the way we seem to handle this for other protocols and I could
> not see an easy way to build multiple modules from a single Makefile.
> 
> I am a tad afraid that this Kconfig clause will cause problems with
> make oldconfig as it stands, and I will be happy to take suggestions
> on how to do this better.
> 
> The other MPLS bits that are added in the following patches are behind
> their own Kconfig options so there is no danger in getting more MPLS
> code than desired.

Thanks, that part seems reasonable to me.

I'm also unsure of a better way to handle this.

Reviewed-by: Simon Horman <horms@verge.net.au>