linux-kernel - Re: [PATCH 4/4] export: avoid code duplication in include/linux/export.h

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Message-ID: <20191011153127.GA1283883@kroah.com>
Date:   Fri, 11 Oct 2019 17:31:27 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     Matthias Maennich <maennich@...gle.com>
Cc:     linux-kernel@...r.kernel.org, kernel-team@...roid.com,
        Jessica Yu <jeyu@...nel.org>,
        Masahiro Yamada <yamada.masahiro@...ionext.com>,
        Martijn Coenen <maco@...roid.com>,
        Lucas De Marchi <lucas.de.marchi@...il.com>,
        Shaun Ruffell <sruffell@...ffell.net>,
        Will Deacon <will@...nel.org>, linux-kbuild@...r.kernel.org,
        linux-modules@...r.kernel.org
Subject: Re: [PATCH 4/4] export: avoid code duplication in
 include/linux/export.h

On Thu, Oct 10, 2019 at 04:14:43PM +0100, Matthias Maennich wrote:
> Now that the namespace value is not part of the __ksymtab entry name
> anymore, we can simplify the implementation of EXPORT_SYMBOL*. By
> allowing the empty string "" to represent 'no namespace', we can unify
> the implementation and drop a lot redundant code.  That increases
> readability and maintainability.
> 
> As Masahiro pointed out earlier,
> "The drawback of this change is, it grows the code size. When the symbol
> has no namespace, sym->namespace was previously NULL, but it is now am
> empty string "". So, it increases 1 byte for every no namespace
> EXPORT_SYMBOL. A typical kernel configuration has 10K exported symbols,
> so it increases 10KB in rough estimation."

10Kb of non-swapable memory isn't good.  But if you care about that, you
can get it back with the option to compile away any non-used symbols,
and that shouldn't be affected by this change, right?

That being said, the code is a lot cleaner, so I have no objection to
it.

Reviewed-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>