When we try to hot-remove a busy virtio-rng device from QEMU monitor,
the device can't be hot-removed. Because virtio-rng driver hangs at
wait_for_completion_killable().
This patch exits the waiting by completing have_data completion before
unregistering, resets data_avail to avoid the hwrng core use wrong
buffer bytes. Before real unregistering we should return -ENODEV for
reading.
When we hot-unplug the device, dd process in guest will exit.
$ dd if=/dev/hwrng of=/dev/null
dd: error reading ‘/dev/hwrng’: No such device
Signed-off-by: Amos Kong <akong@xxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
---
V2: reset data_avail (Amit)
adjust unregister order
---
drivers/char/hw_random/virtio-rng.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)
diff --git a/drivers/char/hw_random/virtio-rng.c b/drivers/char/hw_random/virtio-rng.c
index 2e3139e..e76433b 100644
--- a/drivers/char/hw_random/virtio-rng.c
+++ b/drivers/char/hw_random/virtio-rng.c
@@ -68,6 +68,10 @@ 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_register_done) {
+ return -ENODEV;
+ }
+
if (!vi->busy) {
vi->busy = true;
init_completion(&vi->have_data);
@@ -137,10 +141,14 @@ static void remove_common(struct virtio_device *vdev)
{
struct virtrng_info *vi = vdev->priv;
+ vi->data_avail = 0;
+ complete(&vi->have_data);
vdev->config->reset(vdev);
vi->busy = false;
- if (vi->hwrng_register_done)
+ if (vi->hwrng_register_done) {
+ vi->hwrng_register_done = false;
hwrng_unregister(&vi->hwrng);
+ }
vdev->config->del_vqs(vdev);
ida_simple_remove(&rng_index_ida, vi->index);
kfree(vi);
--
1.9.3
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