[ 3.5.y.z extended stable ] Patch "virtio: rng: disallow multiple device registrations, fixes" has been added to staging queue

Luis Henriques luis.henriques at canonical.com
Tue Mar 19 15:04:37 UTC 2013

This is a note to let you know that I have just added a patch titled

    virtio: rng: disallow multiple device registrations, fixes

to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree 
which can be found at:


If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.5.y.z tree, see



>From 116d36821b357f6001844c8651c1c4945aa8df70 Mon Sep 17 00:00:00 2001
From: Amit Shah <amit.shah at redhat.com>
Date: Fri, 8 Mar 2013 11:30:18 +1100
Subject: [PATCH] virtio: rng: disallow multiple device registrations, fixes

commit e84e7a56a3aa2963db506299e29a5f3f09377f9b upstream.

The code currently only supports one virtio-rng device at a time.
Invoking guests with multiple devices causes the guest to blow up.

Check if we've already registered and initialised the driver.  Also
cleanup in case of registration errors or hot-unplug so that a new
device can be used.

Reported-by: Peter Krempa <pkrempa at redhat.com>
Reported-by: <yunzheng at redhat.com>
Signed-off-by: Amit Shah <amit.shah at redhat.com>
Signed-off-by: Rusty Russell <rusty at rustcorp.com.au>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
 drivers/char/hw_random/virtio-rng.c | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/drivers/char/hw_random/virtio-rng.c b/drivers/char/hw_random/virtio-rng.c
index 723725b..171380b 100644
--- a/drivers/char/hw_random/virtio-rng.c
+++ b/drivers/char/hw_random/virtio-rng.c
@@ -89,14 +89,22 @@ static int virtrng_probe(struct virtio_device *vdev)
 	int err;

+	if (vq) {
+		/* We only support one device for now */
+		return -EBUSY;
+	}
 	/* We expect a single virtqueue. */
 	vq = virtio_find_single_vq(vdev, random_recv_done, "input");
-	if (IS_ERR(vq))
-		return PTR_ERR(vq);
+	if (IS_ERR(vq)) {
+		err = PTR_ERR(vq);
+		vq = NULL;
+		return err;
+	}

 	err = hwrng_register(&virtio_hwrng);
 	if (err) {
+		vq = NULL;
 		return err;

@@ -108,6 +116,7 @@ static void __devexit virtrng_remove(struct virtio_device *vdev)
+	vq = NULL;

 static struct virtio_device_id id_table[] = {

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