Re: [PATCH v0] Crypto: Talitos: re-initialize async_tx descriptors

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

On Mon, Dec 14, 2009 at 6:33 AM, Vishnu Suresh <Vishnu@freescale.com> wrote=
:
> The async_tx descriptors contains dangling pointers.
> Hence, re-initialize them to NULL before use.
>
> Signed-off-by: Vishnu Suresh <Vishnu@freescale.com>
> ---
> o. Rebased to linux-next as of 20091214
>
> =A0drivers/crypto/talitos.c | =A0 =A03 +++
> =A01 files changed, 3 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/crypto/talitos.c b/drivers/crypto/talitos.c
> index 87f06be..9e261c6 100644
> --- a/drivers/crypto/talitos.c
> +++ b/drivers/crypto/talitos.c
> @@ -952,6 +952,9 @@ static struct dma_async_tx_descriptor * talitos_prep_=
dma_xor(
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0return NULL;
> =A0 =A0 =A0 =A0}
> =A0 =A0 =A0 =A0dma_async_tx_descriptor_init(&new->async_tx, &xor_chan->co=
mmon);
> + =A0 =A0 =A0 new->async_tx.parent =3D NULL;
> + =A0 =A0 =A0 new->async_tx.next =3D NULL;
> +
>
> =A0 =A0 =A0 =A0desc =3D &new->hwdesc;
> =A0 =A0 =A0 =A0/* Set destination: Last pointer pair */

These two values are owned by the async_tx api, drivers are not
supposed to touch them.  Both iop_adma and the new ppx4xx driver
(which use the async_tx channel switching capability) get away without
touching these fields which makes me suspect there is a
misunderstanding/bug somewhere else in the talitos implementation.
Also that dma_async_tx_descriptor_init() is unexpected in the hot
path, it's only needed at initial descriptor allocation.  End result I
think this driver needs some more time to brew.

--
Dan