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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>
This commit is contained in:
Heinz Graalfs 2013-10-29 09:40:39 +10:30 committed by Rusty Russell
parent 7f03b17d5c
commit 40e4dc5301
1 changed files with 4 additions and 2 deletions
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6
drivers/char/virtio_console.c
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@ -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);