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Date:   Fri, 27 Sep 2019 20:14:14 +0200
From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     Masahiro Yamada <yamada.masahiro@socionext.com>
Cc:     Matthias Maennich <maennich@google.com>,
        Jessica Yu <jeyu@kernel.org>,
        Joel Fernandes <joel@joelfernandes.org>,
        Martijn Coenen <maco@android.com>,
        Will Deacon <will.deacon@arm.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 7/7] nsdeps: make generated patches independent of locale
Message-ID: <20190927181414.GB1804168@kroah.com>
References: <20190927093603.9140-1-yamada.masahiro@socionext.com>
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 <20190927132726.GB187147@google.com>
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On Sat, Sep 28, 2019 at 12:42:28AM +0900, Masahiro Yamada wrote:
> On Fri, Sep 27, 2019 at 10:27 PM Matthias Maennich <maennich@google.com> wrote:
> >
> > On Fri, Sep 27, 2019 at 06:36:03PM +0900, Masahiro Yamada wrote:
> > >scripts/nsdeps automatically generates a patch to add MODULE_IMPORT_NS
> > >tags, and what is nicer, it sorts the lines alphabetically with the
> > >"sort" command. However, the output from the "sort" command depends
> > >on locale.
> > >
> > >Especially when namespaces contain underscores, the result is
> > >different depending on the locale.
> > >
> > >For example, I got this:
> > >
> > >$ { echo usbcommon; echo usb_common; } | LANG=en_US.UTF-8 sort
> > >usbcommon
> > >usb_common
> > >$ { echo usbcommon; echo usb_common; } | LANG=C sort
> > >usb_common
> > >usbcommon
> > >
> > >So, this means people might potentially send different patches.
> > >
> > >This kind of issue was reported in the past, for example,
> > >commit f55f2328bb28 ("kbuild: make sorting initramfs contents
> > >independent of locale").
> > >
> > >Adding "LANG=C" is a conventional way of fixing when a deterministic
> > >result is desirable.
> > >
> > >Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
> > >---
> > >
> > > scripts/nsdeps | 2 +-
> > > 1 file changed, 1 insertion(+), 1 deletion(-)
> > >
> > >diff --git a/scripts/nsdeps b/scripts/nsdeps
> > >index 964b7fb8c546..3754dac13b31 100644
> > >--- a/scripts/nsdeps
> > >+++ b/scripts/nsdeps
> > >@@ -41,7 +41,7 @@ generate_deps() {
> > >               for source_file in $mod_source_files; do
> > >                       sed '/MODULE_IMPORT_NS/Q' $source_file > ${source_file}.tmp
> > >                       offset=$(wc -l ${source_file}.tmp | awk '{print $1;}')
> > >-                      cat $source_file | grep MODULE_IMPORT_NS | sort -u >> ${source_file}.tmp
> > >+                      cat $source_file | grep MODULE_IMPORT_NS | LANG=C sort -u >> ${source_file}.tmp
> >
> > I would prefer to have this set throughout the whole runtime of the
> > script. Otherwise we likely see a followup patch. So, either as an
> > export at the beginning of this file or as part of the command that
> > calls this script.
> 
> 
> I prefer to keep it close to the locale-dependent code.
> 
> 
> 
> If I move it to somewhere else, I need to add a comment like
> 
> # make "sort" command deterministic
> export LANG=C
> 
> Otherwise, people would have no idea why it is needed.

A comment is fine, it documents why it is here and it keeps anyone from
having to remember to add it to anything else that changes in here.

thanks,

greg k-h