From: Jeff King <peff@peff.net>
Date: Wed, 30 Nov 2016 23:32:04 GMT
Subject: Re: What's cooking in git.git (Nov 2016, #06; Mon, 28)
Message-ID: <20161130233204.ihbrjwwu3yiv4ugq@sigill.intra.peff.net>
In-Reply-To: <20161130232823.GA192901@google.com>

On Wed, Nov 30, 2016 at 03:28:23PM -0800, Brandon Williams wrote:

> So I couldn't find a race condition in the code.  I tracked the problem
> to grep_source_load_file which attempts to run lstat on the file so that
> it can read it into a buffer.  The lstat call fails with ENOENT (which
> conveniently is skipped by the if statement which calls error_errno).  So
> for some reason the file cannot be found and read into memory resulting
> in nothing being grep'ed for that particular file (since the buffer is
> NULL).

That's definitely weird. Is it possible that any of the underlying calls
from another thread are using chdir()? I think realpath() make do that
behind the scenes, and there may be others.

A full strace from a failing case would be interesting reading. In
theory we should be able to get that by running the stress script for
long enough. :)

-Peff