On Mon, May 07, 2018 at 11:21:11PM +0100, Mathieu Xhonneux wrote: > I'm not sure what would be the best approach here. These errors appear > when CONFIG_IPV6=m and CONFIG_IPV6_SEG6_LWTUNNEL=y (which is bool and > depends on IPv6, hence it is also modularized in this case), then > IS_ENABLED(CONFIG_IPV6_SEG6_LWTUNNEL) returns true, even though the > seg6_* symbols are not available when linking vmlinux. If I'm correct, > since net/core/filter.c is always built-in, all functions it uses must > also be built-in. > > I didn't find any other dependency from net/core/filter.c using a > feature which can be modularized, hence the only solution I see here > is to create a new bool CONFIG variable, e.g. CONFIG_IPV6_SEG6_BPF, > which would require CONFIG_IPV6=y and CONFIG_IPV6_SEG6_LWTUNNEL=y. I > could then replace my #if IS_ENABLED(CONFIG_IPV6_SEG6_LWTUNNEL) > conditions by #if IS_ENABLED(CONFIG_IPV6_SEG6_BPF) in > net/core/filter.c.
Requiring CONFIG_IPV6=y for this feature would unfortunate. I think the least ugliest solution would be to add seg6 functions to ipv6_bpf_stub and call them indirectly if they are not in critical path. If it is the fast path then CONFIG_IPV6=y is the only option, but don't expose the new CONFIG_IPV6_SEG6_BPF to the user. Make it automatic y/n depending on CONFIG_IPV6=y or (n|m) > Any comment on this ? > > Thanks. > > 2018-05-07 0:29 GMT+01:00 kbuild test robot <l...@intel.com>: > > Hi Mathieu, > > > > Thank you for the patch! Yet something to improve: > > > > [auto build test ERROR on bpf-next/master] > > > > url: > > https://github.com/0day-ci/linux/commits/Mathieu-Xhonneux/ipv6-sr-introduce-seg6local-End-BPF-action/20180506-233046 > > base: https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git > > master > > config: s390-allmodconfig (attached as .config) > > compiler: s390x-linux-gnu-gcc (Debian 7.2.0-11) 7.2.0 > > reproduce: > > wget > > https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O > > ~/bin/make.cross > > chmod +x ~/bin/make.cross > > # save the attached .config to linux build tree > > make.cross ARCH=s390 > > > > All errors (new ones prefixed by >>): > > > > net/core/filter.o: In function `bpf_push_seg6_encap': > > filter.c:(.text+0xaf4c): undefined reference to `seg6_validate_srh' > > filter.c:(.text+0xaf8a): undefined reference to `seg6_do_srh_inline' > > filter.c:(.text+0xafc4): undefined reference to `seg6_do_srh_encap' > > filter.c:(.text+0xb016): undefined reference to `seg6_lookup_nexthop' > > net/core/filter.o: In function `bpf_lwt_seg6_store_bytes': > >>> (.text+0xb106): undefined reference to `seg6_bpf_srh_states' > > net/core/filter.o: In function `bpf_lwt_seg6_action': > > (.text+0xb2b0): undefined reference to `seg6_bpf_srh_states' > >>> (.text+0xb334): undefined reference to `seg6_validate_srh' > >>> (.text+0xb394): undefined reference to `seg6_lookup_nexthop' > > (.text+0xb3c4): undefined reference to `seg6_lookup_nexthop' > > net/core/filter.o: In function `bpf_lwt_seg6_adjust_srh': > > (.text+0xb492): undefined reference to `seg6_bpf_srh_states' > > > > --- > > 0-DAY kernel test infrastructure Open Source Technology > > Center > > https://lists.01.org/pipermail/kbuild-all Intel > > Corporation
