Subject: [PATCH net v2] virtio_net: fix virtnet_open and virtnet_probe competing for try_fill_recv

From: wangyunjian <[email-masked]>
Date: Thu, 26 May 2016 14:27:59 +0800

In function virtnet_open() and virtnet_probe(), func try_fill_recv()
will be executed at the same time. VQ in virtqueue_add() is not protected
well and BUG_ON will be triggered when virito_net.ko being removed.

Signed-off-by: Yunjian Wang <[email-masked]>
---
 drivers/net/virtio_net.c | 18 ++----------------
 1 file changed, 2 insertions(+), 16 deletions(-)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 49d84e5..e0638e5 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -1925,24 +1925,11 @@ static int virtnet_probe(struct virtio_device *vdev)

        virtio_device_ready(vdev);

-       /* Last of all, set up some receive buffers. */
-       for (i = 0; i < vi->curr_queue_pairs; i++) {
-               try_fill_recv(vi, &vi->rq[i], GFP_KERNEL);
-
-               /* If we didn't even get one input buffer, we're useless. */
-               if (vi->rq[i].vq->num_free ==
-                   virtqueue_get_vring_size(vi->rq[i].vq)) {
-                       free_unused_bufs(vi);
-                       err = -ENOMEM;
-                       goto free_recv_bufs;
-               }
-       }
-
        vi->nb.notifier_call = &virtnet_cpu_callback;
        err = register_hotcpu_notifier(&vi->nb);
        if (err) {
                pr_debug("virtio_net: registering cpu notifier failed\n");
-               goto free_recv_bufs;
+               goto free_unregister_netdev;
        }

        /* Assume link up if device can't report link status,
@@ -1960,10 +1947,9 @@ static int virtnet_probe(struct virtio_device *vdev)

        return 0;

-free_recv_bufs:
+free_unregister_netdev:
        vi->vdev->config->reset(vdev);

-       free_receive_bufs(vi);
        unregister_netdev(dev);
 free_vqs:
        cancel_delayed_work_sync(&vi->refill);