[Precise PATCH] USB: Fix 'bad dma' problem on WDM device disconnect

[Ming Lei]

Hi Leann,

On Thu, Dec 13, 2012 at 1:29 AM, Leann Ogasawara
<leann.ogasawara at canonical.com> wrote:
> Hi Ming,
>
> I'm a little confused here.  This patch was included upstream as of 2.6.39:
>
> ~/linux$ git show 878b753e32ca765cd346a5d3038d630178ec78ff
> commit 878b753e32ca765cd346a5d3038d630178ec78ff
> Author: Robert Lukassen <Robert.Lukassen at tomtom.com>
> Date:   Wed Mar 16 12:13:34 2011 +0100
>
>     USB: Fix 'bad dma' problem on WDM device disconnect
>
> ~/linux$ git describe --contains 878b753e32ca765cd346a5d3038d630178ec78ff
> v2.6.39-rc1~85^2~3
>
> Thus, this patch is already available in Precise by default.  Am I
> missing something here?  Have you tested with a stock Precise kernel?

You are correct, looks I miss that, and the root cause is the below commit,
which is a partial fix, so we still need the patch to avoid the 'bad dma' and
coherent buffer leak. The patch isn't needed for upstream kernel, so need to
push it to stable tree first or you can apply it directly on precise?

commit 7a55df4694e1758a7a1c3b1432e36fca0c859d6a
Author: Bjørn Mork <bjorn at mork.no>
Date:   Mon Jan 16 15:11:59 2012 +0100

    USB: cdc-wdm: better allocate a buffer that is at least as big as
we tell the USB core


Thanks,
--
Ming Lei