1 files changed, 9 insertions, 0 deletions

diff --git a/Documentation/lguest/lguest.c b/Documentation/lguest/lguest.c
index 84c471b07c27..20f8253881b3 100644
--- a/Documentation/lguest/lguest.c
+++ b/Documentation/lguest/lguest.c
@@ -151,6 +151,9 @@ struct virtqueue
         /* Last available index we saw. */
         u16 last_avail_idx;
 
+        /* How many are used since we sent last irq? */
+        unsigned int pending_used;
+
         /* Eventfd where Guest notifications arrive. */
         int eventfd;
 
@@ -556,6 +559,11 @@ static void trigger_irq(struct virtqueue *vq)
 {
         unsigned long buf[] = { LHREQ_IRQ, vq->config.irq };
 
+        /* Don't inform them if nothing used. */
+        if (!vq->pending_used)
+                return;
+        vq->pending_used = 0;
+
         /* If they don't want an interrupt, don't send one, unless empty. */
         if ((vq->vring.avail->flags & VRING_AVAIL_F_NO_INTERRUPT)
             && lg_last_avail(vq) != vq->vring.avail->idx)
@@ -647,6 +655,7 @@ static void add_used(struct virtqueue *vq, unsigned int head, int len)
         /* Make sure buffer is written before we update index. */
         wmb();
         vq->vring.used->idx++;
+        vq->pending_used++;
 }
 
 /* And here's the combo meal deal.  Supersize me! */