Re: [async_tx-next PATCH v2 2/2] fsldma: Fix cookie issues

[Dan Williams <dan.j.williams@intel.com>]

On Thu, Feb 25, 2010 at 12:39 PM, Steven J. Magnani
<steve@digidescorp.com> wrote:
> fsl_dma_update_completed_cookie() appears to calculate the last completed
> cookie incorrectly in the corner case where DMA on cookie 1 is in progres=
s
> just following a cookie wrap.
>
> Signed-off-by: Steven J. Magnani <steve@digidescorp.com>
> ---
> diff -uprN a/drivers/dma/fsldma.c b/drivers/dma/fsldma.c
> --- a/drivers/dma/fsldma.c =A0 =A0 =A02010-02-22 11:16:36.000000000 -0600
> +++ b/drivers/dma/fsldma.c =A0 =A0 =A02010-02-22 11:08:41.000000000 -0600
> @@ -819,8 +819,11 @@ static void fsl_dma_update_completed_coo
> =A0 =A0 =A0 =A0desc =3D to_fsl_desc(chan->ld_running.prev);
> =A0 =A0 =A0 =A0if (dma_is_idle(chan))
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0cookie =3D desc->async_tx.cookie;
> - =A0 =A0 =A0 else
> + =A0 =A0 =A0 else {
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0cookie =3D desc->async_tx.cookie - 1;
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 if (unlikely(cookie < DMA_MIN_COOKIE))
> + =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 cookie =3D DMA_MAX_COOKIE;
> + =A0 =A0 =A0 }
>
> =A0 =A0 =A0 =A0chan->completed_cookie =3D cookie;
>
> diff -uprN a/include/linux/dmaengine.h b/include/linux/dmaengine.h
> --- a/include/linux/dmaengine.h 2010-02-22 11:18:11.000000000 -0600
> +++ b/include/linux/dmaengine.h 2010-02-22 11:18:30.000000000 -0600
> @@ -31,6 +31,8 @@
> =A0* if dma_cookie_t is >0 it's a DMA request cookie, <0 it's an error co=
de
> =A0*/
> =A0typedef s32 dma_cookie_t;
> +#define DMA_MIN_COOKIE 1
> +#define DMA_MAX_COOKIE ((1 << 31) - 1)
>

This patch introduces a new warning::

drivers/dma/fsldma.c:825: warning: integer overflow in expression

I'll fix this up to use INT_MAX instead.

--
Dan

powerpc-linux-gnu-gcc --version
powerpc-linux-gnu-gcc (Sourcery G++ Lite 4.2-50) 4.2.1