[PATCH RFC] vhost: optimize interrupt enable/disable

From: Michael S. Tsirkin
Date: Tue Jul 19 2011 - 11:04:41 EST

As we now only update used ring after enabling
the backend, we can write flags with __put_user:
as that's done on data path, it matters.

Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx>

It seems an obvious optimization so I queued this up

drivers/vhost/vhost.c | 4 ++--
1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index c16d225..c14c42b 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -998,7 +998,7 @@ int vhost_log_write(struct vhost_virtqueue *vq, struct vhost_log *log,
static int vhost_update_used_flags(struct vhost_virtqueue *vq)
void __user *used;
- if (put_user(vq->used_flags, &vq->used->flags) < 0)
+ if (__put_user(vq->used_flags, &vq->used->flags) < 0)
return -EFAULT;
if (unlikely(vq->log_used)) {
/* Make sure the flag is seen before log. */
@@ -1016,7 +1016,7 @@ static int vhost_update_used_flags(struct vhost_virtqueue *vq)

static int vhost_update_avail_event(struct vhost_virtqueue *vq, u16 avail_event)
- if (put_user(vq->avail_idx, vhost_avail_event(vq)))
+ if (__put_user(vq->avail_idx, vhost_avail_event(vq)))
return -EFAULT;
if (unlikely(vq->log_used)) {
void __user *used;
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