virtio: explicit enable_cb/disable_cb rather than callback return.

It seems that virtio_net wants to disable callbacks (interrupts) before
calling netif_rx_schedule(), so we can't use the return value to do so.

Rename "restart" to "cb_enable" and introduce "cb_disable" hook: callback
now returns void, rather than a boolean.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

4 files changed, 26 insertions, 15 deletions

diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
index 1c63d5b64c20..54a8017ad487 100644
--- a/drivers/block/virtio_blk.c
+++ b/drivers/block/virtio_blk.c
@@ -36,7 +36,7 @@ struct virtblk_req
         struct virtio_blk_inhdr in_hdr;
 };
 
-static bool blk_done(struct virtqueue *vq)
+static void blk_done(struct virtqueue *vq)
 {
         struct virtio_blk *vblk = vq->vdev->priv;
         struct virtblk_req *vbr;
@@ -65,7 +65,6 @@ static bool blk_done(struct virtqueue *vq)
         /* In case queue is stopped waiting for more buffers. */
         blk_start_queue(vblk->disk->queue);
         spin_unlock_irqrestore(&vblk->lock, flags);
-        return true;
 }
 
 static bool do_req(struct request_queue *q, struct virtio_blk *vblk,
diff --git a/drivers/lguest/lguest_device.c b/drivers/lguest/lguest_device.c
index 07f57a53658b..ced5b44cebce 100644
--- a/drivers/lguest/lguest_device.c
+++ b/drivers/lguest/lguest_device.c
@@ -191,7 +191,7 @@ static void lg_notify(struct virtqueue *vq)
  * So we provide devices with a "find virtqueue and set it up" function. */
 static struct virtqueue *lg_find_vq(struct virtio_device *vdev,
                                     unsigned index,
-                                    bool (*callback)(struct virtqueue *vq))
+                                    void (*callback)(struct virtqueue *vq))
 {
         struct lguest_device *ldev = to_lgdev(vdev);
         struct lguest_vq_info *lvq;
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 4b8138312750..7b0059f0f5d4 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -52,13 +52,12 @@ static inline void vnet_hdr_to_sg(struct scatterlist *sg, struct sk_buff *skb)
         sg_init_one(sg, skb_vnet_hdr(skb), sizeof(struct virtio_net_hdr));
 }
 
-static bool skb_xmit_done(struct virtqueue *rvq)
+static void skb_xmit_done(struct virtqueue *rvq)
 {
         struct virtnet_info *vi = rvq->vdev->priv;
 
         /* In case we were waiting for output buffers. */
         netif_wake_queue(vi->dev);
-        return true;
 }
 
 static void receive_skb(struct net_device *dev, struct sk_buff *skb,
@@ -161,12 +160,14 @@ static void try_fill_recv(struct virtnet_info *vi)
         vi->rvq->vq_ops->kick(vi->rvq);
 }
 
-static bool skb_recv_done(struct virtqueue *rvq)
+static void skb_recv_done(struct virtqueue *rvq)
 {
         struct virtnet_info *vi = rvq->vdev->priv;
-        netif_rx_schedule(vi->dev, &vi->napi);
-        /* Suppress further interrupts. */
-        return false;
+        /* Schedule NAPI, Suppress further interrupts if successful. */
+        if (netif_rx_schedule_prep(vi->dev, &vi->napi)) {
+                rvq->vq_ops->disable_cb(rvq);
+                __netif_rx_schedule(vi->dev, &vi->napi);
+        }
 }
 
 static int virtnet_poll(struct napi_struct *napi, int budget)
@@ -192,7 +193,7 @@ again:
         /* Out of packets? */
         if (received < budget) {
                 netif_rx_complete(vi->dev, napi);
-                if (unlikely(!vi->rvq->vq_ops->restart(vi->rvq))
+                if (unlikely(!vi->rvq->vq_ops->enable_cb(vi->rvq))
                     && netif_rx_reschedule(vi->dev, napi))
                         goto again;
         }
diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index 1dc04b6684e6..342bb0363fbe 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -220,7 +220,17 @@ static void *vring_get_buf(struct virtqueue *_vq, unsigned int *len)
         return ret;
 }
 
-static bool vring_restart(struct virtqueue *_vq)
+static void vring_disable_cb(struct virtqueue *_vq)
+{
+        struct vring_virtqueue *vq = to_vvq(_vq);
+
+        START_USE(vq);
+        BUG_ON(vq->vring.avail->flags & VRING_AVAIL_F_NO_INTERRUPT);
+        vq->vring.avail->flags |= VRING_AVAIL_F_NO_INTERRUPT;
+        END_USE(vq);
+}
+
+static bool vring_enable_cb(struct virtqueue *_vq)
 {
         struct vring_virtqueue *vq = to_vvq(_vq);
 
@@ -254,8 +264,8 @@ irqreturn_t vring_interrupt(int irq, void *_vq)
                 return IRQ_HANDLED;
 
         pr_debug("virtqueue callback for %p (%p)\n", vq, vq->vq.callback);
-        if (vq->vq.callback && !vq->vq.callback(&vq->vq))
-                vq->vring.avail->flags |= VRING_AVAIL_F_NO_INTERRUPT;
+        if (vq->vq.callback)
+                vq->vq.callback(&vq->vq);
 
         return IRQ_HANDLED;
 }
@@ -264,7 +274,8 @@ static struct virtqueue_ops vring_vq_ops = {
         .add_buf = vring_add_buf,
         .get_buf = vring_get_buf,
         .kick = vring_kick,
-        .restart = vring_restart,
+        .disable_cb = vring_disable_cb,
+        .enable_cb = vring_enable_cb,
         .shutdown = vring_shutdown,
 };
 
@@ -272,7 +283,7 @@ struct virtqueue *vring_new_virtqueue(unsigned int num,
                                       struct virtio_device *vdev,
                                       void *pages,
                                       void (*notify)(struct virtqueue *),
-                                      bool (*callback)(struct virtqueue *))
+                                      void (*callback)(struct virtqueue *))
 {
         struct vring_virtqueue *vq;
         unsigned int i;