Michal reported a build failure likes below:
BTFIDS vmlinux
FAILED unresolved symbol tcp_timewait_sock
make[1]: *** [/.../linux-5.9-rc7/Makefile:1176: vmlinux] Error 255
This error can be triggered when config has CONFIG_NET enabled
but CONFIG_INET disabled. In this case, there is no user of
structs inet_timewait_sock and tcp_timewait_sock and hence vmlinux BTF
types are not generated for these two structures.
To fix the problem, let us force BTF generation for these two
structures with BTF_TYPE_EMIT.
Fixes: fce557bcef11 ("bpf: Make btf_sock_ids global")
Reported-by: Michal Kubecek <mkubecek@xxxxxxx>
Signed-off-by: Yonghong Song <yhs@xxxxxx>
---
net/core/filter.c | 6 ++++++
1 file changed, 6 insertions(+)
Changelog:
v2 -> v3:
. instead of avoiding generating BTF types which is more
complex, just always generating these BTF types (under CONFIG_NET).
v1 -> v2:
. For unsupported socket times, using BTF_ID_UNUSED to
keep the id as 0. (Martin)
diff --git a/net/core/filter.c b/net/core/filter.c
index 21eaf3b182f2..b5f3faac5e3b 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -9558,6 +9558,12 @@ const struct bpf_func_proto bpf_skc_to_tcp_sock_proto = {
BPF_CALL_1(bpf_skc_to_tcp_timewait_sock, struct sock *, sk)
{
+ /* BTF types for tcp_timewait_sock and inet_timewait_sock are not
+ * generated if CONFIG_INET=n. Trigger an explicit generation here.
+ */
+ BTF_TYPE_EMIT(struct inet_timewait_sock);
+ BTF_TYPE_EMIT(struct tcp_timewait_sock);
+
#ifdef CONFIG_INET
if (sk && sk->sk_prot == &tcp_prot && sk->sk_state == TCP_TIME_WAIT)
return (unsigned long)sk;
--
2.24.1
