virtio_console: verify if queue is broken after virtqueue_get_buf()

If virtqueue_get_buf() returns with a NULL pointer it should be verified
if the virtqueue is broken, in order to avoid loop calling cpu_relax().

Signed-off-by: Heinz Graalfs <graalfs@linux.vnet.ibm.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
index 2a8d9a7a18340f4192ff183d0bda3424724477d5..feea87cc6b8fb60a5972be32fee027697006ddf2 100644 (file)
--- a/drivers/char/virtio_console.c
+++ b/drivers/char/virtio_console.c
@@ -577,7 +577,8 @@ static ssize_t __send_control_msg(struct ports_device *portdev, u32 port_id,
        spin_lock(&portdev->c_ovq_lock);
        if (virtqueue_add_outbuf(vq, sg, 1, &cpkt, GFP_ATOMIC) == 0) {
                virtqueue_kick(vq);
-               while (!virtqueue_get_buf(vq, &len))
+               while (!virtqueue_get_buf(vq, &len)
+                       && !virtqueue_is_broken(vq))
                        cpu_relax();
        }
        spin_unlock(&portdev->c_ovq_lock);
@@ -650,7 +651,8 @@ static ssize_t __send_to_port(struct port *port, struct scatterlist *sg,
         * we need to kmalloc a GFP_ATOMIC buffer each time the
         * console driver writes something out.
         */
-       while (!virtqueue_get_buf(out_vq, &len))
+       while (!virtqueue_get_buf(out_vq, &len)
+               && !virtqueue_is_broken(out_vq))
                cpu_relax();
 done:
        spin_unlock_irqrestore(&port->outvq_lock, flags);