Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932191AbaGUML0 (ORCPT ); Mon, 21 Jul 2014 08:11:26 -0400 Received: from mho-03-ewr.mailhop.org ([204.13.248.66]:57109 "EHLO mho-01-ewr.mailhop.org" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753937AbaGUMLZ (ORCPT ); Mon, 21 Jul 2014 08:11:25 -0400 X-Mail-Handler: Dyn Standard SMTP by Dyn X-Originating-IP: 96.249.243.124 X-Report-Abuse-To: abuse@dyndns.com (see http://www.dyndns.com/services/sendlabs/outbound_abuse.html for abuse reporting information) X-MHO-User: U2FsdGVkX18rMZUyC4mpDZYx5/kGpI0YiAQ/59ACc4Y= X-DKIM: OpenDKIM Filter v2.0.1 titan 90F1D5B1499 Date: Mon, 21 Jul 2014 08:11:16 -0400 From: Jason Cooper To: Amit Shah Cc: linux-kernel@vger.kernel.org, Virtualization List , Rusty Russell , herbert@gondor.apana.org.au, keescook@chromium.org, Amos Kong Subject: Re: [PATCH v2 3/4] virtio: rng: delay hwrng_register() till driver is ready Message-ID: <20140721121116.GA18750@titan.lakedaemon.net> References: <91cb7c5b87cf2ba5ef1bacd55a7ee7bc827293a2.1405942162.git.amit.shah@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <91cb7c5b87cf2ba5ef1bacd55a7ee7bc827293a2.1405942162.git.amit.shah@redhat.com> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jul 21, 2014 at 05:15:51PM +0530, Amit Shah wrote: > Instead of calling hwrng_register() in the probe routing, call it in the > scan routine. This ensures that when hwrng_register() is successful, > and it requests a few random bytes to seed the kernel's pool at init, > we're ready to service that request. > > This will also enable us to remove the workaround added previously to > check whether probe was completed, and only then ask for data from the > host. The revert follows in the next commit. > > There's a slight behaviour change here on unsuccessful hwrng_register(). > Previously, when hwrng_unregister() failed, the probe() routine would > fail, and the vqs would be torn down, and driver would be marked not > initialized. Now, the vqs will remain initialized, driver would be > marked initialized as well, but won't be available in the list of RNGs > available to hwrng core. To fix the failures, the procedure remains the > same, i.e. unload and re-load the module, and hope things succeed the > next time around. I'm not too comfortable with this. I'll try to take a closer look tonight, but in the meantime... > Signed-off-by: Amit Shah > --- > drivers/char/hw_random/virtio-rng.c | 25 +++++++++++++++---------- > 1 file changed, 15 insertions(+), 10 deletions(-) > > diff --git a/drivers/char/hw_random/virtio-rng.c b/drivers/char/hw_random/virtio-rng.c > index a156284..d9927eb 100644 > --- a/drivers/char/hw_random/virtio-rng.c > +++ b/drivers/char/hw_random/virtio-rng.c > @@ -35,6 +35,7 @@ struct virtrng_info { > unsigned int data_avail; > int index; > bool busy; > + bool hwrng_register_done; > }; > > static bool probe_done; > @@ -136,15 +137,6 @@ static int probe_common(struct virtio_device *vdev) > return err; > } > > - err = hwrng_register(&vi->hwrng); > - if (err) { > - vdev->config->del_vqs(vdev); > - vi->vq = NULL; > - kfree(vi); > - ida_simple_remove(&rng_index_ida, index); > - return err; > - } > - This needs to stay. register, and failure to do so, should occur in the probe routine. > probe_done = true; > return 0; > } > @@ -152,9 +144,11 @@ static int probe_common(struct virtio_device *vdev) > static void remove_common(struct virtio_device *vdev) > { > struct virtrng_info *vi = vdev->priv; > + > vdev->config->reset(vdev); > vi->busy = false; > - hwrng_unregister(&vi->hwrng); > + if (vi->hwrng_register_done) > + hwrng_unregister(&vi->hwrng); > vdev->config->del_vqs(vdev); > ida_simple_remove(&rng_index_ida, vi->index); > kfree(vi); > @@ -170,6 +164,16 @@ static void virtrng_remove(struct virtio_device *vdev) > remove_common(vdev); > } > > +static void virtrng_scan(struct virtio_device *vdev) > +{ > + struct virtrng_info *vi = vdev->priv; > + int err; > + > + err = hwrng_register(&vi->hwrng); > + if (!err) > + vi->hwrng_register_done = true; Instead, perhaps we should just feed the entropy pool from here? We would still need to prevent the core from doing so. Perhaps back to the flag idea? thx, Jason. > +} > + > #ifdef CONFIG_PM_SLEEP > static int virtrng_freeze(struct virtio_device *vdev) > { > @@ -194,6 +198,7 @@ static struct virtio_driver virtio_rng_driver = { > .id_table = id_table, > .probe = virtrng_probe, > .remove = virtrng_remove, > + .scan = virtrng_scan, > #ifdef CONFIG_PM_SLEEP > .freeze = virtrng_freeze, > .restore = virtrng_restore, > -- > 1.9.3 > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/