Re: [BUG] selftests: af_unix: unix:diag.c does not compile on AlmaLinux 8.7

[Kuniyuki Iwashima]

From: Mirsad Goran Todorovac <mirsad.todorovac@xxxxxxxxxxxx>
Date: Mon, 22 May 2023 20:01:14 +0200
> On 5/22/23 18:28, Kuniyuki Iwashima wrote:
> > From: Mirsad Todorovac <mirsad.todorovac@xxxxxxxxxxxx>
> > Date: Mon, 22 May 2023 17:32:11 +0200
> >> Hi,
> >>
> >> On vanilla AlmaLinux 8.7 (CentOS fork) selftests/net/af_unix/diag_uid.c doesn't
> >> compile out of the box, giving the errors:
> >>
> >> make[2]: Entering directory '/home/marvin/linux/kernel/linux_torvalds/tools/testing/selftests/net/af_unix'
> >> gcc     diag_uid.c  -o /home/marvin/linux/kernel/linux_torvalds/tools/testing/selftests/net/af_unix/diag_uid
> >> diag_uid.c:36:16: error: ‘UDIAG_SHOW_UID’ undeclared here (not in a function); did you mean ‘UDIAG_SHOW_VFS’?
> >>     .udiag_show = UDIAG_SHOW_UID
> >>                   ^~~~~~~~~~~~~~
> >>                   UDIAG_SHOW_VFS
> >> In file included from diag_uid.c:17:
> >> diag_uid.c: In function ‘render_response’:
> >> diag_uid.c:128:28: error: ‘UNIX_DIAG_UID’ undeclared (first use in this function); did you mean ‘UNIX_DIAG_VFS’?
> >>     ASSERT_EQ(attr->rta_type, UNIX_DIAG_UID);
> >>                               ^~~~~~~~~~~~~
> >> ../../kselftest_harness.h:707:13: note: in definition of macro ‘__EXPECT’
> >>     __typeof__(_seen) __seen = (_seen); \
> >>                ^~~~~
> >> diag_uid.c:128:2: note: in expansion of macro ‘ASSERT_EQ’
> >>     ASSERT_EQ(attr->rta_type, UNIX_DIAG_UID);
> >>     ^~~~~~~~~
> >> diag_uid.c:128:28: note: each undeclared identifier is reported only once for each function it appears in
> >>     ASSERT_EQ(attr->rta_type, UNIX_DIAG_UID);
> >>                               ^~~~~~~~~~~~~
> >> ../../kselftest_harness.h:707:13: note: in definition of macro ‘__EXPECT’
> >>     __typeof__(_seen) __seen = (_seen); \
> >>                ^~~~~
> >> diag_uid.c:128:2: note: in expansion of macro ‘ASSERT_EQ’
> >>     ASSERT_EQ(attr->rta_type, UNIX_DIAG_UID);
> >>     ^~~~~~~~~
> >> make[2]: *** [../../lib.mk:147: /home/marvin/linux/kernel/linux_torvalds/tools/testing/selftests/net/af_unix/diag_uid] Error 1
> >>
> >> The correct value is in <uapi/linux/unix_diag.h>:
> >>
> >> include/uapi/linux/unix_diag.h:23:#define UDIAG_SHOW_UID		0x00000040	/* show socket's UID */
> >>
> >> The fix is as follows:
> >>
> >> ---
> >>    tools/testing/selftests/net/af_unix/diag_uid.c | 4 ++++
> >>    1 file changed, 4 insertions(+)
> >>
> >> diff --git a/tools/testing/selftests/net/af_unix/diag_uid.c b/tools/testing/selftests/net/af_unix/diag_uid.c
> >> index 5b88f7129fea..66d75b646d35 100644
> >> --- a/tools/testing/selftests/net/af_unix/diag_uid.c
> >> +++ b/tools/testing/selftests/net/af_unix/diag_uid.c
> >> @@ -16,6 +16,10 @@
> >>
> >>    #include "../../kselftest_harness.h"
> >>
> >> +#ifndef UDIAG_SHOW_UID
> >> +#define UDIAG_SHOW_UID         0x00000040      /* show socket's UID */
> >> +#endif
> >> +
> >>    FIXTURE(diag_uid)
> >>    {
> >>           int netlink_fd;
> >>
> >> --
> >>
> >> However, this patch reveals another undefined value:
> >>
> >> make[2]: Entering directory '/home/marvin/linux/kernel/linux_torvalds/tools/testing/selftests/net/af_unix'
> >> gcc     diag_uid.c  -o /home/marvin/linux/kernel/linux_torvalds/tools/testing/selftests/net/af_unix/diag_uid
> >> In file included from diag_uid.c:17:
> >> diag_uid.c: In function ‘render_response’:
> >> diag_uid.c:132:28: error: ‘UNIX_DIAG_UID’ undeclared (first use in this function); did you mean ‘UNIX_DIAG_VFS’?
> >>     ASSERT_EQ(attr->rta_type, UNIX_DIAG_UID);
> >>                               ^~~~~~~~~~~~~
> >> ../../kselftest_harness.h:707:13: note: in definition of macro ‘__EXPECT’
> >>     __typeof__(_seen) __seen = (_seen); \
> >>                ^~~~~
> >> diag_uid.c:132:2: note: in expansion of macro ‘ASSERT_EQ’
> >>     ASSERT_EQ(attr->rta_type, UNIX_DIAG_UID);
> >>     ^~~~~~~~~
> >> diag_uid.c:132:28: note: each undeclared identifier is reported only once for each function it appears in
> >>     ASSERT_EQ(attr->rta_type, UNIX_DIAG_UID);
> >>                               ^~~~~~~~~~~~~
> >> ../../kselftest_harness.h:707:13: note: in definition of macro ‘__EXPECT’
> >>     __typeof__(_seen) __seen = (_seen); \
> >>                ^~~~~
> >> diag_uid.c:132:2: note: in expansion of macro ‘ASSERT_EQ’
> >>     ASSERT_EQ(attr->rta_type, UNIX_DIAG_UID);
> >>     ^~~~~~~~~
> >> make[2]: *** [../../lib.mk:147: /home/marvin/linux/kernel/linux_torvalds/tools/testing/selftests/net/af_unix/diag_uid] Error 1
> >>
> >> Apparently, AlmaLinux 8.7 lacks this enum UNIX_DIAG_UID:
> >>
> >> diff -u /usr/include/linux/unix_diag.h include/uapi/linux/unix_diag.h
> >> --- /usr/include/linux/unix_diag.h	2023-05-16 13:47:51.000000000 +0200
> >> +++ include/uapi/linux/unix_diag.h	2022-10-12 07:35:58.253481367 +0200
> >> @@ -20,6 +20,7 @@
> >>    #define UDIAG_SHOW_ICONS	0x00000008	/* show pending connections */
> >>    #define UDIAG_SHOW_RQLEN	0x00000010	/* show skb receive queue len */
> >>    #define UDIAG_SHOW_MEMINFO	0x00000020	/* show memory info of a socket */
> >> +#define UDIAG_SHOW_UID		0x00000040	/* show socket's UID */
> >>
> >>    struct unix_diag_msg {
> >>    	__u8	udiag_family;
> >> @@ -40,6 +41,7 @@
> >>    	UNIX_DIAG_RQLEN,
> >>    	UNIX_DIAG_MEMINFO,
> >>    	UNIX_DIAG_SHUTDOWN,
> >> +	UNIX_DIAG_UID,
> >>
> >>    	__UNIX_DIAG_MAX,
> >>    };
> >>
> >> Now, this is a change in enums and there doesn't seem to an easy way out
> >> here. (I think I saw an example, but I cannot recall which thread. I will do
> >> more research.)
> >>
> >> When I included
> >>
> >> # gcc -I ../../../../include diag_uid.c
> >>
> >> I've got the following error:
> >>
> >> [marvin@pc-mtodorov linux_torvalds]$ cd tools/testing/selftests/net/af_unix/
> >> [marvin@pc-mtodorov af_unix]$ gcc  -I ../../../../../include   diag_uid.c  -o
> >> /home/marvin/linux/kernel/linux_torvalds/tools/testing/selftests/net/af_unix/diag_uid
> >> In file included from ../../../../../include/linux/build_bug.h:5,
> >>                    from ../../../../../include/linux/bits.h:21,
> >>                    from ../../../../../include/linux/capability.h:18,
> >>                    from ../../../../../include/linux/netlink.h:6,
> >>                    from diag_uid.c:8:
> >> ../../../../../include/linux/compiler.h:246:10: fatal error: asm/rwonce.h: No such file or directory
> >>    #include <asm/rwonce.h>
> >>             ^~~~~~~~~~~~~~
> >> compilation terminated.
> >> [marvin@pc-mtodorov af_unix]$
> >>
> >> At this point I gave up, as it would be an overkill to change kernel system
> >> header to make a test pass, and this probably wouldn't be accepted upsteam?
> >>
> >> Hope this helps. (If we still want to build on CentOS/AlmaLinux/Rocky 8?)
> > 
> > I launched AlmaLinux/RockyLinux 8.7 and 9.2 with images listed in the pages
> > below.
> > 
> >    https://wiki.almalinux.org/cloud/AWS.html#community-amis
> >    https://rockylinux.org/cloud-images/
> > 
> > The kernel versions in each image were :
> > 
> >    8.7:
> >    Alma  : 4.18.0-425.3.1.el8.x86_64
> >    Rocky : 4.18.0-425.10.1.el8_7.x86_64
> > 
> >    9.2:
> >    Alma  : 5.14.0-284.11.1.el9_2.x86_64
> >    Rocky : 5.14.0-284.11.1.el9_2.x86_64
> > 
> > So, this is not a bug.  It's just because v4.18 does not support
> > UNIX_DIAG_UID, which was introduced in v5.3.
> > 
> > You should install 5.3+ kernel if you want to build the test.
> > 
> > Thanks,
> > Kuniyuki
> 
> Hi, Kuniyuki,
> 
> Good point. However, newer kernel won't save me from old /usr/include
> headers, will it?

Sorry, I meant kernel and kernel-headers package that should be
updated along with kernel.

You should use proper header files that match to the actual kernel
version running on the machine.


> I was actually testing the 6.4-rc3 on AlmaLinux 8.7, as it is my only
> RHEL-based box ...
> 
> What would then be the right action?

make headers_install ?


> If it was a #define instead of enum, I'd probably work around and
> exclude the test that doesn't fit the kernel, or the system call
> would return -EINVAL?
> 
> Including from the includes that came with the kernel might be
> a solution:
> 
> ../../../../../include/uapi/linux/unix_diag.h:44:	UNIX_DIAG_UID,
> 
> Alas, when I try to include, I get these ugly errors:
> 
> [marvin@pc-mtodorov af_unix]$ gcc -I ../../../../../include/ diag_uid.c
> In file included from ../../../../../include/linux/build_bug.h:5,
>                   from ../../../../../include/linux/bits.h:21,
>                   from ../../../../../include/linux/capability.h:18,
>                   from ../../../../../include/linux/netlink.h:6,
>                   from diag_uid.c:8:
> ../../../../../include/linux/compiler.h:246:10: fatal error:
> asm/rwonce.h: No such file or directory
>   #include <asm/rwonce.h>
>            ^~~~~~~~~~~~~~

FWIW, this is provided by kernel-devel package.


> compilation terminated.
> [marvin@pc-mtodorov af_unix]$ vi +246
> ../../../../../include/linux/compiler.h
> [marvin@pc-mtodorov af_unix]$ find ../../../../../include -name rwonce.h
> ../../../../../include/asm-generic/rwonce.h
> [marvin@pc-mtodorov af_unix]$
> 
> Minimum reproducer is:
> 
> [marvin@pc-mtodorov af_unix]$ gcc -I ../../../../../include/ reproducer.c
> In file included from ../../../../../include/linux/build_bug.h:5,
>                   from ../../../../../include/linux/bits.h:21,
>                   from ../../../../../include/linux/capability.h:18,
>                   from ../../../../../include/linux/netlink.h:6,
>                   from reproducer.c:5:
> ../../../../../include/linux/compiler.h:246:10: fatal error:
> asm/rwonce.h: No such file or directory
>   #include <asm/rwonce.h>
>            ^~~~~~~~~~~~~~
> compilation terminated.
> [marvin@pc-mtodorov af_unix]$
> 
> [marvin@pc-mtodorov af_unix]$ nl reproducer.c
> 
>       1	#define _GNU_SOURCE
>       2	#include <linux/netlink.h>
> 
> [marvin@pc-mtodorov af_unix]$
> 
> Am I doing something very stupid right now, for actually I see
> 
> #include <asm/rwonce.h>
> 
> in "include/linux/compiler.h" 248L, 7843C
> 
> while actual rwonce.h is in <asm-generic/rwonce.h>
> 
> [marvin@pc-mtodorov af_unix]$ find ../../../../../include -name rwonce.h
> ../../../../../include/asm-generic/rwonce.h
> [marvin@pc-mtodorov af_unix]$
> 
> I must be doing something wrong, for I see that the kernel compiled
> despite not having include/asm ?
> 
> When looking at the invocations of rwonce.h in the kernel, they seem to
> be equally spread between <asm-generic/rwonce.h> and <asm/rwonce.h> :
> 
> [marvin@pc-mtodorov af_unix]$ grep --include="*.[ch]" -n -w rwonce.h -r ../../../../.. 2> /dev/null | less
> ../../../../../arch/alpha/include/asm/rwonce.h:33:#include <asm-generic/rwonce.h>
> ../../../../../arch/arm64/include/asm/rwonce.h:71:#include <asm-generic/rwonce.h>
> ../../../../../arch/arm64/kvm/hyp/include/nvhe/spinlock.h:18:#include <asm/rwonce.h>
> ../../../../../arch/s390/include/asm/rwonce.h:29:#include <asm-generic/rwonce.h>
> ../../../../../arch/x86/include/generated/asm/rwonce.h:1:#include <asm-generic/rwonce.h>
> ../../../../../include/asm-generic/barrier.h:18:#include <asm/rwonce.h>
> ../../../../../include/kunit/test.h:29:#include <asm/rwonce.h>
> ../../../../../include/linux/compiler.h:246:#include <asm/rwonce.h>
> 
> I figured out I must be doing something wrong or the kernel otherwise
> would not build for me.
> 
> Eventually, the UNIX_DIAG_UID enum is used in only one place:
> 
>          ASSERT_EQ(attr->rta_type, UNIX_DIAG_UID);
> 
> That particular test should fail in case of kernel older than 5.3.

We don't expect it to be run on older kernels in the first place.


> 
> However, I fell into a terrible mess where one thing breaks the other.
> 
> I can't seem to make this work.
> 
> Thanks,
> Mirsad