virtio_ring: change host notification API

Currently a host kick error is silently ignored and not reflected in
the virtqueue of a particular virtio device.

Changing the notify API for guest->host notification seems to be one
prerequisite in order to be able to handle such errors in the context
where the kick is triggered.

This patch changes the notify API. The notify function must return a
bool return value. It returns false if the host notification failed.

Signed-off-by: Heinz Graalfs <graalfs@linux.vnet.ibm.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

2 files changed, 11 insertions, 5 deletions

diff --git a/tools/virtio/virtio_test.c b/tools/virtio/virtio_test.c
index da7a19558281..059cb723f6a7 100644
--- a/tools/virtio/virtio_test.c
+++ b/tools/virtio/virtio_test.c
@@ -41,13 +41,14 @@ struct vdev_info {
         struct vhost_memory *mem;
 };
 
-void vq_notify(struct virtqueue *vq)
+bool vq_notify(struct virtqueue *vq)
 {
         struct vq_info *info = vq->priv;
         unsigned long long v = 1;
         int r;
         r = write(info->kick, &v, sizeof v);
         assert(r == sizeof v);
+        return true;
 }
 
 void vq_callback(struct virtqueue *vq)
diff --git a/tools/virtio/vringh_test.c b/tools/virtio/vringh_test.c
index d053ea40c001..14a4f4cab5b9 100644
--- a/tools/virtio/vringh_test.c
+++ b/tools/virtio/vringh_test.c
@@ -22,7 +22,7 @@ static u64 user_addr_offset;
 #define RINGSIZE 256
 #define ALIGN 4096
 
-static void never_notify_host(struct virtqueue *vq)
+static bool never_notify_host(struct virtqueue *vq)
 {
         abort();
 }
@@ -65,17 +65,22 @@ struct guest_virtio_device {
         unsigned long notifies;
 };
 
-static void parallel_notify_host(struct virtqueue *vq)
+static bool parallel_notify_host(struct virtqueue *vq)
 {
+        int rc;
         struct guest_virtio_device *gvdev;
 
         gvdev = container_of(vq->vdev, struct guest_virtio_device, vdev);
-        write(gvdev->to_host_fd, "", 1);
+        rc = write(gvdev->to_host_fd, "", 1);
+        if (rc < 0)
+                return false;
         gvdev->notifies++;
+        return true;
 }
 
-static void no_notify_host(struct virtqueue *vq)
+static bool no_notify_host(struct virtqueue *vq)
 {
+        return true;
 }
 
 #define NUM_XFERS (10000000)