Re: [PATCH v2 2/2] virtio: rng: ensure reads happen after successful probe

From: Herbert Xu
Date: Thu Jul 10 2014 - 04:45:38 EST


On Wed, Jul 09, 2014 at 12:18:36PM -0400, Jason Cooper wrote:
> On Sat, Jul 05, 2014 at 11:04:53AM +0530, Amit Shah wrote:
> > The hwrng core asks for random data in the hwrng_register() call itself
> > from commit d9e7972619. This doesn't play well with virtio -- the
> > DRIVER_OK bit is only set by virtio core on a successful probe, and
> > we're not yet out of our probe routine when this call is made. This
> > causes the host to not acknowledge any requests we put in the virtqueue,
> > and the insmod or kernel boot process just waits for data to arrive from
> > the host, which never happens.
> >
> > CC: Kees Cook <keescook@xxxxxxxxxxxx>
> > CC: Jason Cooper <jason@xxxxxxxxxxxxxx>
> > CC: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
> > CC: <stable@xxxxxxxxxxxxxxx> # For v3.15+
> > Signed-off-by: Amit Shah <amit.shah@xxxxxxxxxx>
> > ---
> > drivers/char/hw_random/core.c | 6 ++++++
> > drivers/char/hw_random/virtio-rng.c | 10 ++++++++++
> > 2 files changed, 16 insertions(+)
>
> Yeah, I don't think there's any viable way to get random data out of
> virtio-rng at probe time... :-(
>
> Reviewed-by: Jason Cooper <jason@xxxxxxxxxxxxxx>

OK, if there are no more objections I will take these two patches.

Thanks!
--
Email: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/