Re: [PATCH bpf-next 2/2] selftest/bpf: fix rst formatting in readme

[Yonghong Song <yhs@fb.com>]

On 11/24/20 10:29 AM, Andrei Matei wrote:
> Hi Yonghong! Thanks for looking at my patch!
> This is my first patch to the Linux kernel / first time using an
> email-based patch workflow, so I don't know what I'm doing. I hope to
> contribute more to BPF in the future, though.

Thanks for making contributions to bpf ecosystem!

> 
> The patches apply fine to me on bpf-next master (am I supposed to be
> targeting a different branch?), and I've asked someone else to confirm
> too. I've tested with your exact git version. I have a theory about
> what might be going wrong for you, see below.
> 
> Here's what I'm doing:
> 
> # prove I'm on bpf-next master
> $ git show | head -n 5
> commit 91b2db27d3ff9ad29e8b3108dfbf1e2f49fe9bd3
> Author: Song Liu <songliubraving@fb.com>
> Date:   Thu Nov 19 16:28:33 2020 -0800
> 
>      bpf: Simplify task_file_seq_get_next()
> 
> # Download the patches - these are the "raw" links published by
> lore.kernel.org for each of the two emails.
> $ curl https://lore.kernel.org/bpf/20201122022205.57229-1-andreimatei1@gmail.com/raw
>> p1.patch
> $ curl https://lore.kernel.org/bpf/20201122022205.57229-2-andreimatei1@gmail.com/raw
>> p2.patch
> $ git am p1.patch
> Applying: selftest/bpf: fix link in readme
> $ git am p2.patch
> Applying: selftest/bpf: fix rst formatting in readme
> 
> So, it all "works for me". The patches were produced with `git
> format-patch` and sent with `git send-email`. Please let me know if I
> was supposed to do something else.
> 
> With the risk of continuing to not know what I'm talking about, I
> perhaps have a guess about why the patches don't apply for you: if you
> simply copy-pasted the email into your p2.txt, that might not apply
> because a space might be lost from the end of one of the one lines
> that I'm deleting. The patch has a line that reads: "-This is due to a
> llvm BPF backend bug. The fix ". Notice the space at the end of the
> line. At least Gmail doesn't render that space, so if I simply
> copy-paste the patch from my browser, I end up with a corrupted line
> and so it doesn't apply. Perhaps that's your situation?

My email client is mozilla thunderbird. I just right click and save the 
patch email to a file and then try to apply and it failed. I guess
this process may not be friendly to http/https links.

I tried your above curl method and it works. I will switch to your
approach if the patch involves http/https links in the future.
Thanks for the detailed procedure!

> 
> Thanks Yonghong, I appreciate your time!

You are welcome. I tested your patch with rst rendering. It
indeed fixed the formatting. I will ack separately.

> 
> - Andrei
> 
> On Mon, Nov 23, 2020 at 2:22 AM Yonghong Song <yhs@fb.com> wrote:
>>
>>
>>
>> On 11/21/20 6:22 PM, Andrei Matei wrote:
>>> A couple of places in the readme had invalid rst formatting causing the
>>> rendering to be off. This patch fixes them with minimal edits.
>>>
>>> Signed-off-by: Andrei Matei <andreimatei1@gmail.com>
>>> ---
>>>    tools/testing/selftests/bpf/README.rst | 28 ++++++++++++++------------
>>>    1 file changed, 15 insertions(+), 13 deletions(-)
>>
>> I cannot apply patch #2 with my current bpf-next branch.
>>
>> -bash-4.4$ git apply ~/p1.txt
>> -bash-4.4$ git apply ~/p2.txt
>> /home/yhs/p2.txt:34: trailing whitespace.
>> __
>> https://reviews.llvm.org/D85570
>>
>> /home/yhs/p2.txt:52: trailing whitespace.
>> __
>> https://reviews.llvm.org/D78466
>>
>> /home/yhs/p2.txt:70: trailing whitespace.
>> .. _0:
>> https://reviews.llvm.org/D74572
>>
>> /home/yhs/p2.txt:71: trailing whitespace.
>> .. _1:
>> https://reviews.llvm.org/D74668
>>
>> /home/yhs/p2.txt:72: trailing whitespace.
>> .. _2:
>> https://reviews.llvm.org/D85174
>>
>> error: patch failed: tools/testing/selftests/bpf/README.rst:33
>> error: tools/testing/selftests/bpf/README.rst: patch does not apply
>> -bash-4.4$ git --version
>> git version 2.24.1
>> -bash-4.4$
>>
>> Could you help check what is the issue? Maybe the links are presented
>> differently in the patch vs. in the README.rst?
>>
>>>
>>> diff --git a/tools/testing/selftests/bpf/README.rst b/tools/testing/selftests/bpf/README.rst
>>> index 3b8d8885892d..ca064180d4d0 100644
>>> --- a/tools/testing/selftests/bpf/README.rst
>>> +++ b/tools/testing/selftests/bpf/README.rst
>>> @@ -33,11 +33,12 @@ The verifier will reject such code with above error.
>>>    At insn 18 the r7 is indeed unbounded. The later insn 19 checks the bounds and
>>>    the insn 20 undoes map_value addition. It is currently impossible for the
>>>    verifier to understand such speculative pointer arithmetic.
>>> -Hence
>>> -    https://reviews.llvm.org/D85570
>>> -addresses it on the compiler side. It was committed on llvm 12.
>>> +Hence `this patch`__ addresses it on the compiler side. It was committed on llvm 12.
>>> +
>>> +__ https://reviews.llvm.org/D85570
>>>
>>>    The corresponding C code
>>> +
>>>    .. code-block:: c
>>>
>>>      for (int i = 0; i < MAX_CGROUPS_PATH_DEPTH; i++) {
>>> @@ -80,10 +81,11 @@ The symptom for ``bpf_iter/netlink`` looks like
>>>      17: (7b) *(u64 *)(r7 +0) = r2
>>>      only read is supported
>>>
>>> -This is due to a llvm BPF backend bug. The fix
>>> -  https://reviews.llvm.org/D78466
>>> +This is due to a llvm BPF backend bug. `The fix`__
>>>    has been pushed to llvm 10.x release branch and will be
>>> -available in 10.0.1. The fix is available in llvm 11.0.0 trunk.
>>> +available in 10.0.1. The patch is available in llvm 11.0.0 trunk.
>>> +
>>> +__  https://reviews.llvm.org/D78466
>>>
>>>    BPF CO-RE-based tests and Clang version
>>>    =======================================
>>> @@ -97,11 +99,11 @@ them to Clang/LLVM. These sub-tests are going to be skipped if Clang is too
>>>    old to support them, they shouldn't cause build failures or runtime test
>>>    failures:
>>>
>>> -  - __builtin_btf_type_id() ([0], [1], [2]);
>>> -  - __builtin_preserve_type_info(), __builtin_preserve_enum_value() ([3], [4]).
>>> +- __builtin_btf_type_id() [0_, 1_, 2_];
>>> +- __builtin_preserve_type_info(), __builtin_preserve_enum_value() [3_, 4_].
>>>
>>> -  [0] https://reviews.llvm.org/D74572
>>> -  [1] https://reviews.llvm.org/D74668
>>> -  [2] https://reviews.llvm.org/D85174
>>> -  [3] https://reviews.llvm.org/D83878
>>> -  [4] https://reviews.llvm.org/D83242
>>> +.. _0: https://reviews.llvm.org/D74572
>>> +.. _1: https://reviews.llvm.org/D74668
>>> +.. _2: https://reviews.llvm.org/D85174
>>> +.. _3: https://reviews.llvm.org/D83878
>>> +.. _4: https://reviews.llvm.org/D83242
>>>