On 9/30/20 3:59 PM, Martin KaFai Lau wrote:
On Wed, Sep 30, 2020 at 03:50:10PM -0700, Yonghong Song wrote:
On 9/30/20 1:58 PM, Martin KaFai Lau wrote:
On Wed, Sep 30, 2020 at 09:41:09AM -0700, Yonghong Song 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
BTF_SOCK_TYPE_xxx is used in BTF_ID_LIST_GLOBAL(btf_sock_ids) in filter.c
which does not include BTF_SOCK_TYPE_TCP_TW.
However, btf_sock_ids[BTF_SOCK_TYPE_TCP_TW] is still used
in bpf_skc_to_tcp_timewait_sock_proto.
+#endif
+
enum {
#define BTF_SOCK_TYPE(name, str) name,
-BTF_SOCK_TYPE_xxx
+__BTF_SOCK_TYPE_xxx
+__BTF_SOCK_TW_TYPE_xxx
BTF_SOCK_TYPE_TCP_TW is at the end of this enum.
Would btf_sock_ids[BTF_SOCK_TYPE_TCP_TW] always be 0?
No. If CONFIG_INET is y, the above BTF_SOCK_TYPE_xxx contains
__BTF_SOCK_TW_TYPE_xxx
and
btf_sock_ids[BTF_SOCK_TYPE_TCP_TW] will be calculated properly.
But if CONFIG_INET is n, then BTF_SOCK_TYPE_xxx will not contain
__BTF_SOCK_TW_TYPE_xxx
so btf_sock_ids[BTF_SOCK_TYPE_TCP_TW] will have default value 0
as btf_sock_ids is a global.
I could be missing something here.
Why btf_sock_ids[BTF_SOCK_TYPE_TCP_TW] must be 0?
How does BTF_ID_LIST_GLOBAL() know there is a
btf_sock_ids[BTF_SOCK_TYPE_TCP_TW]?
I would expect at least BTF_ID_UNUSED is required.
Otherwise, the value will be whatever follow the last
btf_sock_ids[BTF_SOCK_TYPE_UDP6].
Right, I realized later on when I prepare v2. Will send patch v2 shortly.
Will send v2 to add some comments to make it easy to understand.
#undef BTF_SOCK_TYPE
MAX_BTF_SOCK_TYPE,
};
--
2.24.1
