diff options
| author | Michael S. Tsirkin <mst@redhat.com> | 2015-11-29 13:34:44 +0200 |
|---|---|---|
| committer | Michael S. Tsirkin <mst@redhat.com> | 2015-12-07 17:28:10 +0200 |
| commit | 5fba13b5cf5856e725de35665c37b647323d3b9a (patch) | |
| tree | ddbe8a6688700a93fd7a53d7b16444a40e82729d /drivers/vhost/vhost.c | |
| parent | 55564a02b2ad4dab0c29fd9391d5118592c7fdc8 (diff) | |
| download | lwn-5fba13b5cf5856e725de35665c37b647323d3b9a.tar.gz lwn-5fba13b5cf5856e725de35665c37b647323d3b9a.zip | |
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/vhost/vhost.c')
| -rw-r--r-- | drivers/vhost/vhost.c | 6 |
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); |