ACK/Cmnt: [SRU][J][PATCH 0/1] Fix bpf selftests build failure after v5.15.139 update

[Roxana Nicolescu]

On 26/02/2024 12:11, Stefan Bader wrote:
> On 26.02.24 11:01, Roxana Nicolescu wrote:
>> BugLink: https://bugs.launchpad.net/bugs/2054567
>>
>> SRU justification
>>
>> [Impact]
>> Upstream v5.15.139 (#lp2049432) brought commit
>> "selftests/bpf: Test tail call counting with bpf2bpf and data on stack"
>> that affects one of the bpf kselftests (tailcall_bpf2bpf6).
>> because LIBBPF_OPTS macro does not exists, it does not compile. Error 
>> below.
>>
>> [Fix]
>> Initially, I thought cherry-picking commit
>> "libbpf: Rename DECLARE_LIBBPF_OPTS into LIBBPF_OPTS" would be the best,
>> but upstream stable just reverted the commit that broke it. Hence the 
>> fix
>> consists of cherry-picking this commit from stable upstream 5.15.49:
>
> I think you meant 5.15.149 above (this is also in the cherry picked 
> line of the patch). I would adjust this when applying, probably to 
> linux-5.15.y as that is the branch name upstream uses.
>
Yes, indeed. Thanks!
>> Commit 62900d358c48 (Revert "selftests/bpf: Test tail call counting 
>> with bpf2bpf and data on stack")
>>
>> [Test]
>> This should be solved soon, but compileselftests debian rule does not
>> compile bpf selftests.
>> I tested it by using our regression testing tooling, but same results 
>> can
>> be achieved by running:
>> $ make -C linux/tools/testing/selftests TARGETS=bpf SKIP_TARGETS= 
>> clean all KDIR=/usr/src/linux-headers-5.15.0-<verson>-generic
>> from the linux tree directory
>>
>> Without the fix, it fails to compile:
>> /root/autotest/client/tmp/ubuntu_bpf/src/linux/tools/testing/selftests/bpf/prog_tests/tailcalls.c: 
>> In function ‘test_tailcall_bpf2bpf_6’:
>> /root/autotest/client/tmp/ubuntu_bpf/src/linux/tools/testing/selftests/bpf/prog_tests/tailcalls.c:822:9: 
>> warning: implicit declaration of function ‘LIBBPF_OPTS’; did you mean 
>> ‘LIBBPF_API’? [-Wimplicit-function-declaration]
>>      822 | LIBBPF_OPTS(bpf_test_run_opts, topts,
>>          | ^~~~~~~~~~~
>>          | LIBBPF_API
>> /root/autotest/client/tmp/ubuntu_bpf/src/linux/tools/testing/selftests/bpf/prog_tests/tailcalls.c:822:21: 
>> error: ‘bpf_test_run_opts’ undeclared (first use in this function)
>>      822 | LIBBPF_OPTS(bpf_test_run_opts, topts,
>>          | ^~~~~~~~~~~~~~~~~
>> /root/autotest/client/tmp/ubuntu_bpf/src/linux/tools/testing/selftests/bpf/prog_tests/tailcalls.c:822:21: 
>> note: each undeclared identifier is reported only once for each 
>> function it appears in
>> /root/autotest/client/tmp/ubuntu_bpf/src/linux/tools/testing/selftests/bpf/prog_tests/tailcalls.c:822:40: 
>> error: ‘topts’ undeclared (first use in this function)
>>      822 | LIBBPF_OPTS(bpf_test_run_opts, topts,
>>          | ^~~~~
>> /root/autotest/client/tmp/ubuntu_bpf/src/linux/tools/testing/selftests/bpf/prog_tests/tailcalls.c:823:17: 
>> error: expected expression before ‘.’ token
>>      823 | .data_in = &pkt_v4,
>>          | ^
>>    make[1]: *** [Makefile:471: 
>> /root/autotest/client/tmp/ubuntu_bpf/src/linux/tools/testing/selftests/bpf/tailcalls.test.o] 
>> Error 1
>>    make: *** [Makefile:172: all] Error 2
>>
>> With the fix, it compiles.
>>
>> [Regression potential]
>> The only place this is being used is selftests, so the risk is very low.
>>
>> Samasth Norway Ananda (1):
>>    Revert "selftests/bpf: Test tail call counting with bpf2bpf and data
>>      on stack"
>>
>>   .../selftests/bpf/prog_tests/tailcalls.c      | 55 -------------------
>>   .../selftests/bpf/progs/tailcall_bpf2bpf6.c   | 42 --------------
>>   2 files changed, 97 deletions(-)
>>   delete mode 100644 
>> tools/testing/selftests/bpf/progs/tailcall_bpf2bpf6.c
>>
>
> Acked-by: Stefan Bader <stefan.bader at canonical.com>