On Wed, Sep 30, 2020 at 12:25 PM Yonghong Song <yhs@xxxxxx> wrote:
>
>
>
> On 9/30/20 11:40 AM, Andrii Nakryiko wrote:
> > On Wed, Sep 30, 2020 at 9:41 AM Yonghong Song <yhs@xxxxxx> wrote:
> >>
> >> 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, omit the above two types for BTF_SOCK_TYPE_xxx
> >> macro if CONFIG_INET is not defined.
> >>
> >> Fixes: fce557bcef11 ("bpf: Make btf_sock_ids global")
> >> Reported-by: Michal Kubecek <mkubecek@xxxxxxx>
> >> Signed-off-by: Yonghong Song <yhs@xxxxxx>
> >> ---
> >> include/linux/btf_ids.h | 20 ++++++++++++++++----
> >> 1 file changed, 16 insertions(+), 4 deletions(-)
> >>
> >> diff --git a/include/linux/btf_ids.h b/include/linux/btf_ids.h
> >> index 4867d549e3c1..d9a1e18d0921 100644
> >> --- a/include/linux/btf_ids.h
> >> +++ b/include/linux/btf_ids.h
> >> @@ -102,24 +102,36 @@ asm( \
> >> * skc_to_*_sock() helpers. All these sockets should have
> >> * sock_common as the first argument in its memory layout.
> >> */
> >> -#define BTF_SOCK_TYPE_xxx \
> >> +
> >> +#define __BTF_SOCK_TYPE_xxx \
> >> BTF_SOCK_TYPE(BTF_SOCK_TYPE_INET, inet_sock) \
> >> BTF_SOCK_TYPE(BTF_SOCK_TYPE_INET_CONN, inet_connection_sock) \
> >> BTF_SOCK_TYPE(BTF_SOCK_TYPE_INET_REQ, inet_request_sock) \
> >> - BTF_SOCK_TYPE(BTF_SOCK_TYPE_INET_TW, inet_timewait_sock) \
> >> BTF_SOCK_TYPE(BTF_SOCK_TYPE_REQ, request_sock) \
> >> BTF_SOCK_TYPE(BTF_SOCK_TYPE_SOCK, sock) \
> >> BTF_SOCK_TYPE(BTF_SOCK_TYPE_SOCK_COMMON, sock_common) \
> >> BTF_SOCK_TYPE(BTF_SOCK_TYPE_TCP, tcp_sock) \
> >> BTF_SOCK_TYPE(BTF_SOCK_TYPE_TCP_REQ, tcp_request_sock) \
> >> - BTF_SOCK_TYPE(BTF_SOCK_TYPE_TCP_TW, tcp_timewait_sock) \
> >> BTF_SOCK_TYPE(BTF_SOCK_TYPE_TCP6, tcp6_sock) \
> >> BTF_SOCK_TYPE(BTF_SOCK_TYPE_UDP, udp_sock) \
> >> BTF_SOCK_TYPE(BTF_SOCK_TYPE_UDP6, udp6_sock)
> >>
> >> +#define __BTF_SOCK_TW_TYPE_xxx \
> >> + BTF_SOCK_TYPE(BTF_SOCK_TYPE_INET_TW, inet_timewait_sock) \
> >> + BTF_SOCK_TYPE(BTF_SOCK_TYPE_TCP_TW, tcp_timewait_sock)
> >> +
> >> +#ifdef CONFIG_INET
> >> +#define BTF_SOCK_TYPE_xxx \
> >> + __BTF_SOCK_TYPE_xxx \
> >> + __BTF_SOCK_TW_TYPE_xxx
> >> +#else
> >> +#define BTF_SOCK_TYPE_xxx __BTF_SOCK_TYPE_xxx
> >> +#endif
> >> +
> >> enum {
> >> #define BTF_SOCK_TYPE(name, str) name,
> >> -BTF_SOCK_TYPE_xxx
> >> +__BTF_SOCK_TYPE_xxx
> >> +__BTF_SOCK_TW_TYPE_xxx
> >
> > Why BTF_SOCK_TYPE_xxx doesn't still work here after the above changes?
>
> The macro, e.g., BTF_SOCK_TYPE_TCP_TW, still needed to be defined as
> it is used to get the location for btf_id.
Ah, right, so you want those here unconditionally, even if CONFIG_INET
is not defined. Missed that. Might be worth leaving a short comment.
Otherwise LGTM.
Acked-by: Andrii Nakryiko <andriin@xxxxxx>
>
> const struct bpf_func_proto bpf_skc_to_tcp_timewait_sock_proto = {
> .func = bpf_skc_to_tcp_timewait_sock,
> .gpl_only = false,
> .ret_type = RET_PTR_TO_BTF_ID_OR_NULL,
> .arg1_type = ARG_PTR_TO_BTF_ID_SOCK_COMMON,
> .ret_btf_id = &btf_sock_ids[BTF_SOCK_TYPE_TCP_TW],
> };
>
> If CONFIG_INET is not defined, bpf_sock_ids[BTF_SOCK_TYPE_TCP_TW]
> will be 0.
>
> >
> >> #undef BTF_SOCK_TYPE
> >> MAX_BTF_SOCK_TYPE,
> >> };
> >> --
> >> 2.24.1
> >>
