virtio-rng: skip reading when we start to remove the device

Before we really unregister the hwrng device, reading will get stuck if
the virtio device is reset. We should return error for reading when we
start to remove the device.

Signed-off-by: Amos Kong <akong@redhat.com>
Reviewed-by: Amit Shah <amit.shah@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

diff --git a/drivers/char/hw_random/virtio-rng.c b/drivers/char/hw_random/virtio-rng.c
index 849b22877196fa6749df2bf6e5e164f241e2b281..132c9ccfdc62b382cb22a9870e44038c6495a39d 100644 (file)
--- a/drivers/char/hw_random/virtio-rng.c
+++ b/drivers/char/hw_random/virtio-rng.c
@@ -36,6 +36,7 @@ struct virtrng_info {
        int index;
        bool busy;
        bool hwrng_register_done;
+       bool hwrng_removed;
 };
 
 
@@ -68,6 +69,9 @@ static int virtio_read(struct hwrng *rng, void *buf, size_t size, bool wait)
        int ret;
        struct virtrng_info *vi = (struct virtrng_info *)rng->priv;
 
+       if (vi->hwrng_removed)
+               return -ENODEV;
+
        if (!vi->busy) {
                vi->busy = true;
                init_completion(&vi->have_data);
@@ -137,6 +141,7 @@ static void remove_common(struct virtio_device *vdev)
 {
        struct virtrng_info *vi = vdev->priv;
 
+       vi->hwrng_removed = true;
        vi->data_avail = 0;
        complete(&vi->have_data);
        vdev->config->reset(vdev);