virtio-rng: Remove false BUG for spurious callbacks

upstream commit: e5b89542ea18020961882228c26db3ba87f6e608

The virtio-rng drivers checks for spurious callbacks. Since
callbacks can be implemented via shared interrupts (e.g. PCI) this
could lead to guest kernel oopses with lots of virtio devices.

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>

diff --git a/drivers/char/hw_random/virtio-rng.c b/drivers/char/hw_random/virtio-rng.c
index d0e563e4fc399bf37f06a4d19cea0bfcb5017713..86e83f883139e154d8f8621b2aa6650468ed74d8 100644 (file)
--- a/drivers/char/hw_random/virtio-rng.c
+++ b/drivers/char/hw_random/virtio-rng.c
@@ -37,9 +37,9 @@ static void random_recv_done(struct virtqueue *vq)
 {
        int len;
 
-       /* We never get spurious callbacks. */
+       /* We can get spurious callbacks, e.g. shared IRQs + virtio_pci. */
        if (!vq->vq_ops->get_buf(vq, &len))
-               BUG();
+               return;
 
        data_left = len / sizeof(random_data[0]);
        complete(&have_data);