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Date: Thu, 21 Mar 2013 10:18:38 -0400
Message-ID: <CAG6tG3xyZYWgB2nUwwu8mmkSJza-cXym6iHivOUSJuYf3pV5_w@mail.gmail.com>
Subject: Re: [BUG] staging: android: ashmem: Deadlock during ashmem_mmap and ashmem_read
From: Robert Love <rlove@google.com>
To: Bjorn Bringert <bringert@google.com>
Cc: Shankar Brahadeeswaran <shankoo77@gmail.com>,
        Dan Carpenter <dan.carpenter@oracle.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Konstantin Khlebnikov <khlebnikov@openvz.org>,
        devel@driverdev.osuosl.org, LKML <linux-kernel@vger.kernel.org>,
        Hugh Dickins <hughd@google.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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On Thu, Mar 21, 2013 at 10:06 AM, Bjorn Bringert <bringert@google.com> wrote:
> I did implement ashmem_read, but I had no idea what I was doing. Calling the
> VFS read function seemed like an obvious way to do it, but it might be
> wrong. If that needs fixing, then the similar VFS call in ashmem_llseek
> probably needs fixing too.

You don't want to hold ashmem_mutex across the VFS calls. It is only
needed to protect the ashmem-internal structures.

FWIW is Android now using ashmem_read()? I left it out of the original
ashmem implementation on purpose.

        Robert
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