[Qemu-devel] [PATCH v4 04/13] virtio-blk: Move complete_request to 'ops' structure

[Fam Zheng <famz@redhat.com>]

Should more ops be added to differentiate code between dataplane and
non-dataplane, the new saved_ops approach will be cleaner than messing
with N pointers.

Signed-off-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
---
 hw/block/dataplane/virtio-blk.c | 13 ++++++++-----
 hw/block/virtio-blk.c           |  8 ++++++--
 include/hw/virtio/virtio-blk.h  |  9 +++++++--
 3 files changed, 21 insertions(+), 9 deletions(-)

diff --git a/hw/block/dataplane/virtio-blk.c b/hw/block/dataplane/virtio-blk.c
index 3ecc8bd..e287e09 100644
--- a/hw/block/dataplane/virtio-blk.c
+++ b/hw/block/dataplane/virtio-blk.c
@@ -51,8 +51,7 @@ struct VirtIOBlockDataPlane {
 
     /* Operation blocker on BDS */
     Error *blocker;
-    void (*saved_complete_request)(struct VirtIOBlockReq *req,
-                                   unsigned char status);
+    const VirtIOBlockOps *saved_ops;
 };
 
 /* Raise an interrupt to signal guest, if necessary */
@@ -88,6 +87,10 @@ static void complete_request_vring(VirtIOBlockReq *req, unsigned char status)
     qemu_bh_schedule(s->bh);
 }
 
+static const VirtIOBlockOps virtio_blk_data_plane_ops = {
+    .complete_request = complete_request_vring,
+};
+
 static void handle_notify(EventNotifier *e)
 {
     VirtIOBlockDataPlane *s = container_of(e, VirtIOBlockDataPlane,
@@ -270,8 +273,8 @@ void virtio_blk_data_plane_start(VirtIOBlockDataPlane *s)
     }
     s->host_notifier = *virtio_queue_get_host_notifier(vq);
 
-    s->saved_complete_request = vblk->complete_request;
-    vblk->complete_request = complete_request_vring;
+    s->saved_ops = vblk->ops;
+    vblk->ops = &virtio_blk_data_plane_ops;
 
     s->starting = false;
     s->started = true;
@@ -314,7 +317,7 @@ void virtio_blk_data_plane_stop(VirtIOBlockDataPlane *s)
         return;
     }
     s->stopping = true;
-    vblk->complete_request = s->saved_complete_request;
+    vblk->ops = s->saved_ops;
     trace_virtio_blk_data_plane_stop(s);
 
     aio_context_acquire(s->ctx);
diff --git a/hw/block/virtio-blk.c b/hw/block/virtio-blk.c
index e6afe97..f4a9d19 100644
--- a/hw/block/virtio-blk.c
+++ b/hw/block/virtio-blk.c
@@ -59,9 +59,13 @@ static void virtio_blk_complete_request(VirtIOBlockReq *req,
     virtio_notify(vdev, s->vq);
 }
 
+static const VirtIOBlockOps virtio_blk_ops = (VirtIOBlockOps) {
+    .complete_request = virtio_blk_complete_request,
+};
+
 static void virtio_blk_req_complete(VirtIOBlockReq *req, unsigned char status)
 {
-    req->dev->complete_request(req, status);
+    req->dev->ops->complete_request(req, status);
 }
 
 static int virtio_blk_handle_rw_error(VirtIOBlockReq *req, int error,
@@ -905,7 +909,7 @@ static void virtio_blk_device_realize(DeviceState *dev, Error **errp)
     s->sector_mask = (s->conf.conf.logical_block_size / BDRV_SECTOR_SIZE) - 1;
 
     s->vq = virtio_add_queue(vdev, 128, virtio_blk_handle_output);
-    s->complete_request = virtio_blk_complete_request;
+    s->ops = &virtio_blk_ops;
     virtio_blk_data_plane_create(vdev, conf, &s->dataplane, &err);
     if (err != NULL) {
         error_propagate(errp, err);
diff --git a/include/hw/virtio/virtio-blk.h b/include/hw/virtio/virtio-blk.h
index 6bf5905..28b3436 100644
--- a/include/hw/virtio/virtio-blk.h
+++ b/include/hw/virtio/virtio-blk.h
@@ -44,6 +44,12 @@ struct VirtIOBlkConf
 struct VirtIOBlockDataPlane;
 
 struct VirtIOBlockReq;
+
+typedef struct {
+    /* Function to push to vq and notify guest */
+    void (*complete_request)(struct VirtIOBlockReq *req, unsigned char status);
+} VirtIOBlockOps;
+
 typedef struct VirtIOBlock {
     VirtIODevice parent_obj;
     BlockBackend *blk;
@@ -54,8 +60,7 @@ typedef struct VirtIOBlock {
     unsigned short sector_mask;
     bool original_wce;
     VMChangeStateEntry *change;
-    /* Function to push to vq and notify guest */
-    void (*complete_request)(struct VirtIOBlockReq *req, unsigned char status);
+    const VirtIOBlockOps *ops;
     Notifier migration_state_notifier;
     struct VirtIOBlockDataPlane *dataplane;
 } VirtIOBlock;
-- 
2.4.1