linux-kernel - Re: [BUG] staging: android: ashmem: Deadlock during ashmem_mmap and ashmem

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Message-ID: <CAG6tG3xyZYWgB2nUwwu8mmkSJza-cXym6iHivOUSJuYf3pV5_w@mail.gmail.com>
Date:	Thu, 21 Mar 2013 10:18:38 -0400
From:	Robert Love <rlove@...gle.com>
To:	Bjorn Bringert <bringert@...gle.com>
Cc:	Shankar Brahadeeswaran <shankoo77@...il.com>,
	Dan Carpenter <dan.carpenter@...cle.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Konstantin Khlebnikov <khlebnikov@...nvz.org>,
	devel@...verdev.osuosl.org, LKML <linux-kernel@...r.kernel.org>,
	Hugh Dickins <hughd@...gle.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: Re: [BUG] staging: android: ashmem: Deadlock during ashmem_mmap and ashmem_read

On Thu, Mar 21, 2013 at 10:06 AM, Bjorn Bringert <bringert@...gle.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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