From: Michael S. Tsirkin <mst@redhat.com>
Date: Thu, 5 Mar 2015 02:54:41 +0000 (+1030)
Subject: virtio_balloon: set DRIVER_OK before using device
X-Git-Tag: v3.19.4~57
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=757fd0d78d090eb2518b09a5903d312e3955c08d;p=thirdparty%2Fkernel%2Fstable.git

virtio_balloon: set DRIVER_OK before using device

commit 88660f7fb94cda1f8f63ee92bfcd0db39a6361e2 upstream.

virtio spec requires that all drivers set DRIVER_OK
before using devices. While balloon isn't yet
included in the virtio 1 spec, previous spec versions
also required this.

virtio balloon might violate this rule: probe calls
kthread_run before setting DRIVER_OK, which might run
immediately and cause balloon to inflate/deflate.

To fix, call virtio_device_ready before running the kthread.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
index 50c5f42d7a9f3..8a969320ad423 100644
--- a/drivers/virtio/virtio_balloon.c
+++ b/drivers/virtio/virtio_balloon.c
@@ -494,6 +494,8 @@ static int virtballoon_probe(struct virtio_device *vdev)
 	if (err < 0)
 		goto out_oom_notify;
 
+	virtio_device_ready(vdev);
+
 	vb->thread = kthread_run(balloon, vb, "vballoon");
 	if (IS_ERR(vb->thread)) {
 		err = PTR_ERR(vb->thread);