[PATCH bpf 1/2] net/ipv4: fix linux/in.h header dependencies

[PATCH bpf 1/2] net/ipv4: fix linux/in.h header dependencies

[Andrii Nakryiko]

__DECLARE_FLEX_ARRAY is defined in include/uapi/linux/stddef.h but
doesn't seem to be explicitly included from include/uapi/linux/in.h,
which breaks BPF selftests builds (once we sync linux/stddef.h into
tools/include directory in the next patch). Fix this by explicitly
including linux/stddef.h.

Given this affects BPF CI and bpf tree, targeting this for bpf tree.

Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Gustavo A. R. Silva <gustavoars@kernel.org>
Fixes: 5854a09b4957 ("net/ipv4: Use __DECLARE_FLEX_ARRAY() helper")
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
---
 include/uapi/linux/in.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/include/uapi/linux/in.h b/include/uapi/linux/in.h
index f243ce665f74..07a4cb149305 100644
--- a/include/uapi/linux/in.h
+++ b/include/uapi/linux/in.h
@@ -20,6 +20,7 @@
 #define _UAPI_LINUX_IN_H
 
 #include <linux/types.h>
+#include <linux/stddef.h>
 #include <linux/libc-compat.h>
 #include <linux/socket.h>
 
-- 
2.30.2

[PATCH bpf 2/2] tools headers uapi: pull in stddef.h to fix BPF selftests build in CI

[Andrii Nakryiko]

With recent sync of linux/in.h tools/include headers are now relying on
__DECLARE_FLEX_ARRAY macro, which isn't itself defined inside
tools/include headers anywhere and is instead assumed to be present in
system-wide UAPI header. This breaks isolated environments that don't
have kernel UAPI headers installed system-wide, like BPF CI ([0]).

To fix this, bring in include/uapi/linux/stddef.h into tools/include. We
can't just copy/paste it, though, it has to be processed with
scripts/headers_install.sh, which has a dependency on scripts/unifdef.
So the full command to (re-)generate stddef.h for inclusion into
tools/include directory is:

  $ make scripts_unifdef && \
    cp $KBUILD_OUTPUT/scripts/unifdef scripts/ && \
    scripts/headers_install.sh include/uapi/linux/stddef.h tools/include/uapi/linux/stddef.h

This assumes KBUILD_OUTPUT envvar is set and used for out-of-tree builds.

  [0] https://github.com/kernel-patches/bpf/actions/runs/3379432493/jobs/5610982609

Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Fixes: 036b8f5b8970 ("tools headers uapi: Update linux/in.h copy")
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
---
 tools/include/uapi/linux/in.h     |  1 +
 tools/include/uapi/linux/stddef.h | 47 +++++++++++++++++++++++++++++++
 2 files changed, 48 insertions(+)
 create mode 100644 tools/include/uapi/linux/stddef.h

diff --git a/tools/include/uapi/linux/in.h b/tools/include/uapi/linux/in.h
index f243ce665f74..07a4cb149305 100644
--- a/tools/include/uapi/linux/in.h
+++ b/tools/include/uapi/linux/in.h
@@ -20,6 +20,7 @@
 #define _UAPI_LINUX_IN_H
 
 #include <linux/types.h>
+#include <linux/stddef.h>
 #include <linux/libc-compat.h>
 #include <linux/socket.h>
 
diff --git a/tools/include/uapi/linux/stddef.h b/tools/include/uapi/linux/stddef.h
new file mode 100644
index 000000000000..bb6ea517efb5
--- /dev/null
+++ b/tools/include/uapi/linux/stddef.h
@@ -0,0 +1,47 @@
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+#ifndef _LINUX_STDDEF_H
+#define _LINUX_STDDEF_H
+
+
+
+#ifndef __always_inline
+#define __always_inline __inline__
+#endif
+
+/**
+ * __struct_group() - Create a mirrored named and anonyomous struct
+ *
+ * @TAG: The tag name for the named sub-struct (usually empty)
+ * @NAME: The identifier name of the mirrored sub-struct
+ * @ATTRS: Any struct attributes (usually empty)
+ * @MEMBERS: The member declarations for the mirrored structs
+ *
+ * Used to create an anonymous union of two structs with identical layout
+ * and size: one anonymous and one named. The former's members can be used
+ * normally without sub-struct naming, and the latter can be used to
+ * reason about the start, end, and size of the group of struct members.
+ * The named struct can also be explicitly tagged for layer reuse, as well
+ * as both having struct attributes appended.
+ */
+#define __struct_group(TAG, NAME, ATTRS, MEMBERS...) \
+	union { \
+		struct { MEMBERS } ATTRS; \
+		struct TAG { MEMBERS } ATTRS NAME; \
+	}
+
+/**
+ * __DECLARE_FLEX_ARRAY() - Declare a flexible array usable in a union
+ *
+ * @TYPE: The type of each flexible array element
+ * @NAME: The name of the flexible array member
+ *
+ * In order to have a flexible array member in a union or alone in a
+ * struct, it needs to be wrapped in an anonymous struct with at least 1
+ * named member, but that member can be empty.
+ */
+#define __DECLARE_FLEX_ARRAY(TYPE, NAME)	\
+	struct { \
+		struct { } __empty_ ## NAME; \
+		TYPE NAME[]; \
+	}
+#endif
-- 
2.30.2

Re: [PATCH bpf 1/2] net/ipv4: fix linux/in.h header dependencies

[patchwork-bot+netdevbpf]

Hello:

This series was applied to bpf/bpf.git (master)
by Daniel Borkmann <daniel@iogearbox.net>:

On Wed, 2 Nov 2022 11:25:16 -0700 you wrote:
> __DECLARE_FLEX_ARRAY is defined in include/uapi/linux/stddef.h but
> doesn't seem to be explicitly included from include/uapi/linux/in.h,
> which breaks BPF selftests builds (once we sync linux/stddef.h into
> tools/include directory in the next patch). Fix this by explicitly
> including linux/stddef.h.
> 
> Given this affects BPF CI and bpf tree, targeting this for bpf tree.
> 
> [...]

Here is the summary with links:
  - [bpf,1/2] net/ipv4: fix linux/in.h header dependencies
    https://git.kernel.org/bpf/bpf/c/aec1dc972d27
  - [bpf,2/2] tools headers uapi: pull in stddef.h to fix BPF selftests build in CI
    https://git.kernel.org/bpf/bpf/c/a778f5d46b62

You are awesome, thank you!
-- 
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html

Re: [PATCH bpf 1/2] net/ipv4: fix linux/in.h header dependencies

[Yonghong Song]

On 11/3/22 5:50 AM, patchwork-bot+netdevbpf@kernel.org wrote:
> Hello:
> 
> This series was applied to bpf/bpf.git (master)
> by Daniel Borkmann <daniel@iogearbox.net>:
> 
> On Wed, 2 Nov 2022 11:25:16 -0700 you wrote:
>> __DECLARE_FLEX_ARRAY is defined in include/uapi/linux/stddef.h but
>> doesn't seem to be explicitly included from include/uapi/linux/in.h,
>> which breaks BPF selftests builds (once we sync linux/stddef.h into
>> tools/include directory in the next patch). Fix this by explicitly
>> including linux/stddef.h.
>>
>> Given this affects BPF CI and bpf tree, targeting this for bpf tree.
>>
>> [...]
> 
> Here is the summary with links:
>    - [bpf,1/2] net/ipv4: fix linux/in.h header dependencies
>      https://git.kernel.org/bpf/bpf/c/aec1dc972d27
>    - [bpf,2/2] tools headers uapi: pull in stddef.h to fix BPF selftests build in CI
>      https://git.kernel.org/bpf/bpf/c/a778f5d46b62

Can we put this patch set into bpf-next as well? Apparently we have the 
same issue in bpf-next.

> 
> You are awesome, thank you!

Re: [PATCH bpf 1/2] net/ipv4: fix linux/in.h header dependencies

[Andrii Nakryiko]

On Thu, Nov 3, 2022 at 9:18 AM Yonghong Song <yhs@meta.com> wrote:
>
>
>
> On 11/3/22 5:50 AM, patchwork-bot+netdevbpf@kernel.org wrote:
> > Hello:
> >
> > This series was applied to bpf/bpf.git (master)
> > by Daniel Borkmann <daniel@iogearbox.net>:
> >
> > On Wed, 2 Nov 2022 11:25:16 -0700 you wrote:
> >> __DECLARE_FLEX_ARRAY is defined in include/uapi/linux/stddef.h but
> >> doesn't seem to be explicitly included from include/uapi/linux/in.h,
> >> which breaks BPF selftests builds (once we sync linux/stddef.h into
> >> tools/include directory in the next patch). Fix this by explicitly
> >> including linux/stddef.h.
> >>
> >> Given this affects BPF CI and bpf tree, targeting this for bpf tree.
> >>
> >> [...]
> >
> > Here is the summary with links:
> >    - [bpf,1/2] net/ipv4: fix linux/in.h header dependencies
> >      https://git.kernel.org/bpf/bpf/c/aec1dc972d27
> >    - [bpf,2/2] tools headers uapi: pull in stddef.h to fix BPF selftests build in CI
> >      https://git.kernel.org/bpf/bpf/c/a778f5d46b62
>
> Can we put this patch set into bpf-next as well? Apparently we have the
> same issue in bpf-next.
>

Unfortunately we can't because they are already in bpf, and if we have
them in bpf-next, they will cause merge conflicts. So I currently
cherry-pick those two patches locally when compiling selftests. This
should hopefully will be fixed soon and bpf and bpf-next will
converge.

> >
> > You are awesome, thank you!

Re: [PATCH bpf 1/2] net/ipv4: fix linux/in.h header dependencies

[Yonghong Song]

On 11/7/22 4:56 PM, Andrii Nakryiko wrote:
> On Thu, Nov 3, 2022 at 9:18 AM Yonghong Song <yhs@meta.com> wrote:
>>
>>
>>
>> On 11/3/22 5:50 AM, patchwork-bot+netdevbpf@kernel.org wrote:
>>> Hello:
>>>
>>> This series was applied to bpf/bpf.git (master)
>>> by Daniel Borkmann <daniel@iogearbox.net>:
>>>
>>> On Wed, 2 Nov 2022 11:25:16 -0700 you wrote:
>>>> __DECLARE_FLEX_ARRAY is defined in include/uapi/linux/stddef.h but
>>>> doesn't seem to be explicitly included from include/uapi/linux/in.h,
>>>> which breaks BPF selftests builds (once we sync linux/stddef.h into
>>>> tools/include directory in the next patch). Fix this by explicitly
>>>> including linux/stddef.h.
>>>>
>>>> Given this affects BPF CI and bpf tree, targeting this for bpf tree.
>>>>
>>>> [...]
>>>
>>> Here is the summary with links:
>>>     - [bpf,1/2] net/ipv4: fix linux/in.h header dependencies
>>>       https://git.kernel.org/bpf/bpf/c/aec1dc972d27
>>>     - [bpf,2/2] tools headers uapi: pull in stddef.h to fix BPF selftests build in CI
>>>       https://git.kernel.org/bpf/bpf/c/a778f5d46b62
>>
>> Can we put this patch set into bpf-next as well? Apparently we have the
>> same issue in bpf-next.
>>
> 
> Unfortunately we can't because they are already in bpf, and if we have
> them in bpf-next, they will cause merge conflicts. So I currently
> cherry-pick those two patches locally when compiling selftests. This
> should hopefully will be fixed soon and bpf and bpf-next will
> converge.

Thanks. This should be fine. I guess most people will do the same
thing (cherry-pick locally).

> 
>>>
>>> You are awesome, thank you!