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>

1 files changed, 4 insertions, 2 deletions

diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
index 2a8d9a7a1834..feea87cc6b8f 100644
--- 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);