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authorMichael S. Tsirkin <mst@redhat.com>2015-11-29 13:34:44 +0200
committerMichael S. Tsirkin <mst@redhat.com>2015-12-07 17:28:10 +0200
commit5fba13b5cf5856e725de35665c37b647323d3b9a (patch)
treeddbe8a6688700a93fd7a53d7b16444a40e82729d /drivers
parent55564a02b2ad4dab0c29fd9391d5118592c7fdc8 (diff)
vhost: replace % with & on data path
We know vring num is a power of 2, so use & to mask the high bits. Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/vhost/vhost.c6
1 files changed, 3 insertions, 3 deletions
diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index 080422f5464f..ad2146a9ab2d 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -1369,7 +1369,7 @@ int vhost_get_vq_desc(struct vhost_virtqueue *vq,
/* Grab the next descriptor number they're advertising, and increment
* the index we've seen. */
if (unlikely(__get_user(ring_head,
- &vq->avail->ring[last_avail_idx % vq->num]))) {
+ &vq->avail->ring[last_avail_idx & (vq->num - 1)]))) {
vq_err(vq, "Failed to read head: idx %d address %p\n",
last_avail_idx,
&vq->avail->ring[last_avail_idx % vq->num]);
@@ -1489,7 +1489,7 @@ static int __vhost_add_used_n(struct vhost_virtqueue *vq,
u16 old, new;
int start;
- start = vq->last_used_idx % vq->num;
+ start = vq->last_used_idx & (vq->num - 1);
used = vq->used->ring + start;
if (count == 1) {
if (__put_user(heads[0].id, &used->id)) {
@@ -1531,7 +1531,7 @@ int vhost_add_used_n(struct vhost_virtqueue *vq, struct vring_used_elem *heads,
{
int start, n, r;
- start = vq->last_used_idx % vq->num;
+ start = vq->last_used_idx & (vq->num - 1);
n = vq->num - start;
if (n < count) {
r = __vhost_add_used_n(vq, heads, n);