Re: build failure (BTFIDS) with CONFIG_NET && !CONFIG_INET

Yonghong Song <yhs@xxxxxx> · Tue, 29 Sep 2020 21:57:58 -0700

On 9/29/20 3:17 AM, Michal Kubecek wrote:
Hello,

our builds of s390x for zfcpdump fail since 5.9-rc1 with

     BTFIDS  vmlinux
   FAILED unresolved symbol tcp_timewait_sock
   make[1]: *** [/home/abuild/rpmbuild/BUILD/kernel-zfcpdump-5.9.rc7/linux-5.9-rc7/Makefile:1176: vmlinux] Error 255

I believe this is caused by commit fce557bcef11 ("bpf: Make btf_sock_ids
global") and the problem is caused by a specific configuration which has
CONFIG_NET enabled but CONFIG_INET disabled. IIUC there will be no user
of struct tcp_timewait_sock but btf_ids will try to generate BTF info
for it.

Thanks for reporting! Will send a patch to fix the issue soon.

Michal