[PATCH RFC v4 2/5] vhost/test: add an option to test new code

["Michael S. Tsirkin" <mst@redhat.com>]

Add a writeable module parameter that tests
the new code. Note: no effort was made to ensure
things work correctly if the parameter is changed
while the device is open. Make sure to
close the device before changing its value.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
 drivers/vhost/test.c | 17 +++++++++++++----
 1 file changed, 13 insertions(+), 4 deletions(-)

diff --git a/drivers/vhost/test.c b/drivers/vhost/test.c
index 056308008288..39a018a7af2d 100644
--- a/drivers/vhost/test.c
+++ b/drivers/vhost/test.c
@@ -18,6 +18,9 @@
 #include "test.h"
 #include "vhost.h"
 
+static int newcode = 0;
+module_param(newcode, int, 0644);
+
 /* Max number of bytes transferred before requeueing the job.
  * Using this limit prevents one virtqueue from starving others. */
 #define VHOST_TEST_WEIGHT 0x80000
@@ -58,10 +61,16 @@ static void handle_vq(struct vhost_test *n)
 	vhost_disable_notify(&n->dev, vq);
 
 	for (;;) {
-		head = vhost_get_vq_desc(vq, vq->iov,
-					 ARRAY_SIZE(vq->iov),
-					 &out, &in,
-					 NULL, NULL);
+		if (newcode)
+			head = vhost_get_vq_desc_batch(vq, vq->iov,
+						       ARRAY_SIZE(vq->iov),
+						       &out, &in,
+						       NULL, NULL);
+		else
+			head = vhost_get_vq_desc(vq, vq->iov,
+						 ARRAY_SIZE(vq->iov),
+						 &out, &in,
+						 NULL, NULL);
 		/* On error, stop handling until the next kick. */
 		if (unlikely(head < 0))
 			break;
-- 
MST