[B.A.T.M.A.N.] Duplicate #include guards with make-kpkg / out-of-tree compile errors

[B.A.T.M.A.N.] Duplicate #include guards with make-kpkg / out-of-tree compile errors

[Linus Lüssing]

Hi Ben and others,

Recently we stumbled upon some compile errors when trying to build
a backport version of the batman-adv kernel module for a 4.5 kernel [0]:

    "implicit declaration of function ‘G_TC_AT’"

It seems VirtualBox has stumbled over this issue, too [1].

When trying to find the cause of these errors we noticed that the
headers directory created via "$ make-kpkg kernel_headers" for 4.5
kernel resulted in two differing header files with the same guard,
namely __LINUX_PKT_CLS_H:

https://metameute.de/~tux/batman-adv/net-sched-issues/linux-headers-4.5.0%2b/include/uapi/linux/pkt_cls.h
https://metameute.de/~tux/batman-adv/net-sched-issues/linux-headers-4.5.0%2b/include/linux/pkt_cls.h

The latter, the non-uapi version, has the "#ifdef __KERNEL__"
section stripped, causing the compile issue if it is included
before the uapi variant.

Removing this non-uapi version from the unpacked
linux-headers .deb package manually afterwards lets
a batman-adv compilation succeed again.

Daniel (CC) has helped a lot with debugging so far and he
expressed the suspicion that maybe make-kpkg might install
"$ make headers_install" into the wrong directory?

Regards, Linus

[0]: https://www.open-mesh.org/issues/322
[1]: https://www.virtualbox.org/ticket/15327

PS: make-kpkg was invoked on a Debian Jessie (kernel-package
13.014+nmu1).

Re: [B.A.T.M.A.N.] Duplicate #include guards with make-kpkg / out-of-tree compile errors

[Ben Hutchings]

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kernel-package is maintained by Manoj Srivastava (cc'd), not the kernel
team.

Ben.

On Sat, 2017-01-14 at 22:28 +0100, Linus Lüssing wrote:
> Hi Ben and others,
> 
> Recently we stumbled upon some compile errors when trying to build
> a backport version of the batman-adv kernel module for a 4.5 kernel
> [0]:
> 
>     "implicit declaration of function ‘G_TC_AT’"
> 
> It seems VirtualBox has stumbled over this issue, too [1].
> 
> When trying to find the cause of these errors we noticed that the
> headers directory created via "$ make-kpkg kernel_headers" for 4.5
> kernel resulted in two differing header files with the same guard,
> namely __LINUX_PKT_CLS_H:
> 
> https://metameute.de/~tux/batman-adv/net-sched-issues/linux-headers-4
> .5.0%2b/include/uapi/linux/pkt_cls.h
> https://metameute.de/~tux/batman-adv/net-sched-issues/linux-headers-4
> .5.0%2b/include/linux/pkt_cls.h
> 
> The latter, the non-uapi version, has the "#ifdef __KERNEL__"
> section stripped, causing the compile issue if it is included
> before the uapi variant.
> 
> Removing this non-uapi version from the unpacked
> linux-headers .deb package manually afterwards lets
> a batman-adv compilation succeed again.
> 
> Daniel (CC) has helped a lot with debugging so far and he
> expressed the suspicion that maybe make-kpkg might install
> "$ make headers_install" into the wrong directory?
> 
> Regards, Linus
> 
> [0]: https://www.open-mesh.org/issues/322
> [1]: https://www.virtualbox.org/ticket/15327
> 
> PS: make-kpkg was invoked on a Debian Jessie (kernel-package
> 13.014+nmu1).
-- 
Ben Hutchings
Hoare's Law of Large Problems:
        Inside every large problem is a small problem struggling to get
out.


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Re: [B.A.T.M.A.N.] Duplicate #include guards with make-kpkg / out-of-tree compile errors

[Daniel Borkmann]

On 01/15/2017 01:50 AM, Ben Hutchings wrote:
> kernel-package is maintained by Manoj Srivastava (cc'd), not the kernel
> team.
>
> Ben.
>
> On Sat, 2017-01-14 at 22:28 +0100, Linus Lüssing wrote:
>> Hi Ben and others,
>>
>> Recently we stumbled upon some compile errors when trying to build
>> a backport version of the batman-adv kernel module for a 4.5 kernel
>> [0]:
>>
>>      "implicit declaration of function ‘G_TC_AT’"
>>
>> It seems VirtualBox has stumbled over this issue, too [1].
>>
>> When trying to find the cause of these errors we noticed that the
>> headers directory created via "$ make-kpkg kernel_headers" for 4.5
>> kernel resulted in two differing header files with the same guard,
>> namely __LINUX_PKT_CLS_H:
>>
>> https://metameute.de/~tux/batman-adv/net-sched-issues/linux-headers-4
>> .5.0%2b/include/uapi/linux/pkt_cls.h
>> https://metameute.de/~tux/batman-adv/net-sched-issues/linux-headers-4
>> .5.0%2b/include/linux/pkt_cls.h
>>
>> The latter, the non-uapi version, has the "#ifdef __KERNEL__"
>> section stripped, causing the compile issue if it is included
>> before the uapi variant.
>>
>> Removing this non-uapi version from the unpacked
>> linux-headers .deb package manually afterwards lets
>> a batman-adv compilation succeed again.
>>
>> Daniel (CC) has helped a lot with debugging so far and he
>> expressed the suspicion that maybe make-kpkg might install
>> "$ make headers_install" into the wrong directory?

Just to elaborate why I think it's strange, from above link the
include/linux/ directory contains the normal kernel headers we
have in the source tree, and the include/uapi/linux/ the expected
uapi headers. However, the post-processed uapi header files can
also be found in include/linux/. For example, if there's a name
collision (bpf.h as one example), then the post-processed uapi
header was not installed into include/linux/ and the normal kernel
header can still be seen there. If there was no naming collision
like in pkt_cls.h case, then it gets installed into include/linux/
as well. That seems at least rather strange to me, unless there's
a good reason for doing that which I'm not aware of.

>> Regards, Linus
>>
>> [0]: https://www.open-mesh.org/issues/322
>> [1]: https://www.virtualbox.org/ticket/15327
>>
>> PS: make-kpkg was invoked on a Debian Jessie (kernel-package
>> 13.014+nmu1).

Re: [B.A.T.M.A.N.] Duplicate #include guards with make-kpkg / out-of-tree compile errors

[Linus Lüssing]

Hi Ben,

Due to the missing response we went for a workaround in the
out-of-tree backports version of batman-adv for now.

However, it seems a similar issue now popped up with 4.11-rc1
again: [0] ("fatal error: sys/socket.h: No such file or directory")

Second try: Manoj, do you see a chance to fix these two issues
([0][1]) in kernel-package or is this package currently
unmaintained?

Anything I can help with for further debugging in kernel-package?

Regards, Linus

[0]: https://www.open-mesh.org/issues/333
[1]: https://www.open-mesh.org/issues/322


On Sun, Jan 15, 2017 at 12:50:52AM +0000, Ben Hutchings wrote:
> kernel-package is maintained by Manoj Srivastava (cc'd), not the kernel
> team.
> 
> Ben.
> 
> On Sat, 2017-01-14 at 22:28 +0100, Linus Lüssing wrote:
> > Hi Ben and others,
> > 
> > Recently we stumbled upon some compile errors when trying to build
> > a backport version of the batman-adv kernel module for a 4.5 kernel
> > [0]:
> > 
> >     "implicit declaration of function ‘G_TC_AT’"
> > 
> > It seems VirtualBox has stumbled over this issue, too [1].
> > 
> > When trying to find the cause of these errors we noticed that the
> > headers directory created via "$ make-kpkg kernel_headers" for 4.5
> > kernel resulted in two differing header files with the same guard,
> > namely __LINUX_PKT_CLS_H:
> > 
> > https://metameute.de/~tux/batman-adv/net-sched-issues/linux-headers-4
> > .5.0%2b/include/uapi/linux/pkt_cls.h
> > https://metameute.de/~tux/batman-adv/net-sched-issues/linux-headers-4
> > .5.0%2b/include/linux/pkt_cls.h
> > 
> > The latter, the non-uapi version, has the "#ifdef __KERNEL__"
> > section stripped, causing the compile issue if it is included
> > before the uapi variant.
> > 
> > Removing this non-uapi version from the unpacked
> > linux-headers .deb package manually afterwards lets
> > a batman-adv compilation succeed again.
> > 
> > Daniel (CC) has helped a lot with debugging so far and he
> > expressed the suspicion that maybe make-kpkg might install
> > "$ make headers_install" into the wrong directory?
> > 
> > Regards, Linus
> > 
> > [0]: https://www.open-mesh.org/issues/322
> > [1]: https://www.virtualbox.org/ticket/15327
> > 
> > PS: make-kpkg was invoked on a Debian Jessie (kernel-package
> > 13.014+nmu1).
> -- 
> Ben Hutchings
> Hoare's Law of Large Problems:
>         Inside every large problem is a small problem struggling to get
> out.
>