linux-kernel - Re: [PATCH v4 03/18] kunit: test: add string_stream a std::stream like string builder

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Message-ID: <CAFd5g45WrARi7eXsVKyq2eJH5j+wSrCCaHHSHrMptG7+MnNiTg@mail.gmail.com>
Date:   Tue, 4 Jun 2019 17:19:28 -0700
From:   Brendan Higgins <brendanhiggins@...gle.com>
To:     Stephen Boyd <sboyd@...nel.org>
Cc:     Frank Rowand <frowand.list@...il.com>,
        Greg KH <gregkh@...uxfoundation.org>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
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        Luis Chamberlain <mcgrof@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Rob Herring <robh@...nel.org>, shuah <shuah@...nel.org>,
        "Theodore Ts'o" <tytso@....edu>,
        Masahiro Yamada <yamada.masahiro@...ionext.com>,
        devicetree <devicetree@...r.kernel.org>,
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Subject: Re: [PATCH v4 03/18] kunit: test: add string_stream a std::stream
 like string builder

On Fri, May 17, 2019 at 10:43 AM Stephen Boyd <sboyd@...nel.org> wrote:
>
> Quoting Brendan Higgins (2019-05-14 15:16:56)
> > A number of test features need to do pretty complicated string printing
> > where it may not be possible to rely on a single preallocated string
> > with parameters.
> >
> > So provide a library for constructing the string as you go similar to
> > C++'s std::string.
> >
> > Signed-off-by: Brendan Higgins <brendanhiggins@...gle.com>
> > Reviewed-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> > Reviewed-by: Logan Gunthorpe <logang@...tatee.com>
>
> Is there any reason why we can't use the seqfile API for this? These
> both share a similar goal, formatting strings into a buffer to be read
> later. Maybe some new APIs would be needed to extract the buffer
> differently, but I hope we could share the code.

I can see why you are asking. It seems as though they are trying to do
*similar* things, and it seems possible that we might be able to
extract some common functionality out of seq_file that could replace
this; however, it looks like it would be require a significant
refactoring of seq_file to separate out the file system specific bits
from the more general stringbuilder functionality.

In my opinion, a refactoring like this makes no sense in this
patchset; it probably belongs in its own patchset (preferably as a
follow on). I also am not sure if the FS people would appreciate
indirection that serves them no benefit, but I can ask if you like.

> If it can't be used, can you please add the reasoning to the commit text
> here?

Will do.

Thanks!