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Commit 9ff4cfab authored by Rusty Russell's avatar Rusty Russell
Browse files

virtio: console makes incorrect assumption about virtio API 



The get_buf() API sets the second arg to the number of bytes *written*
by the other side; in this case it should be zero as these are output buffers.

lguest gets this right (obviously kvm's console doesn't), resulting in
continual buildup of console writes.

Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
Acked-by: default avatarAmit Shah <amit.shah@redhat.com>
parent 162a689a

drivers/char/virtio_console.c

+3 −7
Original line number Original line Diff line number Diff line
@@ -416,20 +416,16 @@ static ssize_t send_buf(struct port *port, void *in_buf, size_t in_count) 
	out_vq->vq_ops->kick(out_vq);

	out_vq->vq_ops->kick(out_vq);





	if (ret < 0) {

	if (ret < 0) {

		len = 0;

		in_count = 0;

		goto fail;

		goto fail;

	}

	}





	/*

	/* Wait till the host acknowledges it pushed out the data we sent. */

	 * Wait till the host acknowledges it pushed out the data we

	 * sent. Also ensure we return to userspace the number of

	 * bytes that were successfully consumed by the host.

	 */

	while (!out_vq->vq_ops->get_buf(out_vq, &len))

	while (!out_vq->vq_ops->get_buf(out_vq, &len))

		cpu_relax();

		cpu_relax();

fail:

fail:

	/* We're expected to return the amount of data we wrote */

	/* We're expected to return the amount of data we wrote */

	return len;

	return in_count;

}

}





/*

/*