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Date:   Tue, 6 Nov 2018 18:58:13 -0800 (PST)
From:   Christian Kujau <lists@nerdbynature.de>
To:     Brian Norris <briannorris@chromium.org>
cc:     Genki Sky <sky@genki.is>, Guenter Roeck <linux@roeck-us.net>,
        Masahiro Yamada <yamada.masahiro@socionext.com>,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH] Revert "scripts/setlocalversion: git: Make -dirty check
 more robust"
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On Tue, 6 Nov 2018, Brian Norris wrote:
> > Perhaps both scenarios could be satisfied by having
> > scripts/setlocalversion first check if .git has write permissions, and
> > acting accordingly. Looking into history, this actually used to be
> > done, but cdf2bc632ebc ("scripts/setlocalversion on write-protected
> > source tree", 2013-06-14) removed the updating of the index.
> 
> A "writeable" check (e.g., [ -w . ]) would be sufficient for our case.
> But I'm not so sure about that older NFS report, and I'm also not sure
> that we should be writing to the source tree at all in this case. Maybe
> we can also check whether there's a build output directory specified?

FWIW, the issue I reported back in 2013[0] was not an ill-configured NFS 
export, but a read-only NFS export (and then a read-write exported NFS 
export, but the user compiling the kernel did not have write permission) 
and so "test -w .git" did not help in determining if the source tree can 
actually written to. And depending on the user's shell[1], this may or may 
not still be the case.

So I'm all for the $(touch .git/some-file-here) test to decide if the 
kernel has to be modified during build.

Christian. 

[0] https://lkml.org/lkml/2013/6/14/574
[1] https://manpages.debian.org/unstable/dash/dash.1.en.html

> > However, I admit I don't understand the justification in that commit
> > from 2013. I'm no NFS expert, but perhaps the real problem there is an
> > incorrectly configured NFS setup (uid/gid mismatch between NFS
> > client/server, or permissions mismatch between mount options and NFS
> > server?). Christian Kujau: can you speak to that?
> > 
> > Well, we could also make our check $(touch .git/some-file-here
> > 2>/dev/null && ...) instead of $(test -w .git) to handle misconfigured
> > NFS setups. But not sure if that has its own problems.
> 
> Trying to 'touch' the source tree will also break us. No matter whether
> you redirect stderr, our sandbox will still notice the build is doing
> something fishy and complain.

-- 
BOFH excuse #192:

runaway cat on system.