From: Jiri Olsa <jolsa@xxxxxxxxxx> commit f1d41f7720c89705c20e4335a807b1c518c2e7be upstream. The btf_sock_ids array needs struct mptcp_sock BTF ID for the bpf_skc_to_mptcp_sock helper. When CONFIG_MPTCP is disabled, the 'struct mptcp_sock' is not defined and resolve_btfids will complain with: [...] BTFIDS vmlinux WARN: resolve_btfids: unresolved symbol mptcp_sock [...] Add an empty definition for struct mptcp_sock when CONFIG_MPTCP is disabled. Fixes: 3bc253c2e652 ("bpf: Add bpf_skc_to_mptcp_sock_proto") Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx> Signed-off-by: Daniel Borkmann <daniel@xxxxxxxxxxxxx> Reviewed-by: Mat Martineau <mathew.j.martineau@xxxxxxxxxxxxxxx> Acked-by: Martin KaFai Lau <kafai@xxxxxx> Link: https://lore.kernel.org/bpf/20220802163324.1873044-1-jolsa@xxxxxxxxxx Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- include/net/mptcp.h | 4 ++++ 1 file changed, 4 insertions(+) --- a/include/net/mptcp.h +++ b/include/net/mptcp.h @@ -290,4 +290,8 @@ struct mptcp_sock *bpf_mptcp_sock_from_s static inline struct mptcp_sock *bpf_mptcp_sock_from_subflow(struct sock *sk) { return NULL; } #endif +#if !IS_ENABLED(CONFIG_MPTCP) +struct mptcp_sock { }; +#endif + #endif /* __NET_MPTCP_H */