virtio_balloon: don't crash if virtqueue is broken.

A bad implementation of virtio might cause us to mark the virtqueue
broken: we'll dev_err() in that case, and the device is useless, but
let's not BUG().

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

1 files changed, 3 insertions, 5 deletions

diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
index 36e7859a31aa..25ebe8eecdb7 100644
--- a/drivers/virtio/virtio_balloon.c
+++ b/drivers/virtio/virtio_balloon.c
@@ -108,8 +108,7 @@ static void tell_host(struct virtio_balloon *vb, struct virtqueue *vq)
         sg_init_one(&sg, vb->pfns, sizeof(vb->pfns[0]) * vb->num_pfns);
 
         /* We should always be able to add one buffer to an empty queue. */
-        if (virtqueue_add_outbuf(vq, &sg, 1, vb, GFP_KERNEL) < 0)
-                BUG();
+        virtqueue_add_outbuf(vq, &sg, 1, vb, GFP_KERNEL);
         virtqueue_kick(vq);
 
         /* When host has read buffer, this completes via balloon_ack */
@@ -258,8 +257,7 @@ static void stats_handle_request(struct virtio_balloon *vb)
         if (!virtqueue_get_buf(vq, &len))
                 return;
         sg_init_one(&sg, vb->stats, sizeof(vb->stats));
-        if (virtqueue_add_outbuf(vq, &sg, 1, vb, GFP_KERNEL) < 0)
-                BUG();
+        virtqueue_add_outbuf(vq, &sg, 1, vb, GFP_KERNEL);
         virtqueue_kick(vq);
 }
 
@@ -344,7 +342,7 @@ static int init_vqs(struct virtio_balloon *vb)
 
                 /*
                  * Prime this virtqueue with one buffer so the hypervisor can
-                 * use it to signal us later.
+                 * use it to signal us later (it can't be broken yet!).
                  */
                 sg_init_one(&sg, vb->stats, sizeof vb->stats);
                 if (virtqueue_add_outbuf(vb->stats_vq, &sg, 1, vb, GFP_KERNEL)