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Commit 40e4dc53 authored by Heinz Graalfs's avatar Heinz Graalfs Committed by Rusty Russell
Browse files

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: default avatarHeinz Graalfs <graalfs@linux.vnet.ibm.com>
Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
parent 7f03b17d

drivers/char/virtio_console.c

+4 −2
Original line number Diff line number Diff line
@@ -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);