linux-kernel - Re: [PATCHv2] perf bpf: Fix endianness problem when loading parameters in prologue

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Date:   Tue, 15 Aug 2017 08:42:08 +0200
From:   Thomas-Mich Richter <tmricht@...ux.vnet.ibm.com>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:     wangnan0@...wei.com, linux-perf-users@...r.kernel.org,
        linux-kernel@...r.kernel.org, brueckner@...ux.vnet.ibm.com
Subject: Re: [PATCHv2] perf bpf: Fix endianness problem when loading
 parameters in prologue

On 08/14/2017 06:39 PM, Arnaldo Carvalho de Melo wrote:
> Em Mon, Aug 14, 2017 at 01:46:44PM +0200, Thomas Richter escreveu:
>> Perf BPF prologue generator unconditionally fetches 8 bytes for function
>> parameters, which causes problem on big endian machine. Thomas gives a
>> detail analysis for this problem:
>>
>>  http://lkml.kernel.org/r/968ebda5-abe4-8830-8d69-49f62529d151@linux.vnet.ibm.com
>>
>> This patch parses the type of each argument and converts data from
>> memory to expected type.
>>
>> Now the test runs successfully on 4.13.0-rc5:
>> [root@...60046 perf]# ./perf test  bpf
>> 38: BPF filter                                 :
>> 38.1: Basic BPF filtering                      : Ok
>> 38.2: BPF pinning                              : Ok
>> 38.3: BPF prologue generation                  : Ok
>> 38.4: BPF relocation checker                   : Ok
>> [root@...60046 perf]#
>>
>> Signed-off-by: Thomas Richter <tmricht@...ux.vnet.ibm.com>
>> Signed-off-by: Wang Nan <wangnan0@...wei.com>
>> Acked-by: Wang Nan <wangnan0@...wei.com>
>> Tested-by: Wang Nan <wangnan0@...wei.com>
> 
> 
> That is strange, who is the author of the patch? Also I think Tested-by
> is enough, being an even stronger form of Acked-by?
> 
> But then you also have Signed-off-by: Wang in there...
> 
> From Documentation/process/submitting-patches.rst:
> 
> ---------
> 
> 12) When to use Acked-by: and Cc:
> ---------------------------------
> 
> The Signed-off-by: tag indicates that the signer was involved in the
> development of the patch, or that he/she was in the patch's delivery path.
> 
> If a person was not directly involved in the preparation or handling of a
> patch but wishes to signify and record their approval of it then they can
> ask to have an Acked-by: line added to the patch's changelog.
> 
> Acked-by: is often used by the maintainer of the affected code when that
> maintainer neither contributed to nor forwarded the patch.
> 
> ------------------
> 
> If Wang wrote the original patch and you made it better working together
> with him, probably having both of you in Signed-off-by lines should be
> enough?
> 
> - Arnaldo
> 

Ok, my fault then.
Wang wrote to patch in the first place, I just fixed one line.
Should I resend the patch and delete the Acked-by/Tested-by lines
in the commit message?

Thanks

-- 
Thomas Richter, Dept 3303, IBM LTC Boeblingen Germany
--
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