Re: [Qemu-devel] [PATCH 5/8] virtio-blk: fix "disabled data plane" mode

[Paolo Bonzini]

On 15/02/2016 18:58, Cornelia Huck wrote:
> It seems a bit odd to me that ->started is the only state that is not
> inside the dataplane struct... this approach saves a function call for
> an accessor, though.

Actually, I can do better by moving the flag entirely within
hw/block/virtio-blk.c:

diff --git a/hw/block/dataplane/virtio-blk.c b/hw/block/dataplane/virtio-blk.c
index cc521c1..29db94b 100644
--- a/hw/block/dataplane/virtio-blk.c
+++ b/hw/block/dataplane/virtio-blk.c
@@ -263,7 +263,7 @@ void virtio_blk_data_plane_start(VirtIOBlockDataPlane *s)
     VirtQueue *vq;
     int r;
 
-    if (vblk->dataplane_started || s->starting) {
+    if (s->starting) {
         return;
     }
 
@@ -295,7 +295,6 @@ void virtio_blk_data_plane_start(VirtIOBlockDataPlane *s)
     vblk->complete_request = complete_request_vring;
 
     s->starting = false;
-    vblk->dataplane_started = true;
     trace_virtio_blk_data_plane_start(s);
 
     blk_set_aio_context(s->conf->conf.blk, s->ctx);
@@ -317,7 +316,6 @@ void virtio_blk_data_plane_start(VirtIOBlockDataPlane *s)
   fail_vring:
     s->disabled = true;
     s->starting = false;
-    vblk->dataplane_started = true;
 }
 
 /* Context: QEMU global mutex held */
@@ -327,14 +325,13 @@ void virtio_blk_data_plane_stop(VirtIOBlockDataPlane *s)
     VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
     VirtIOBlock *vblk = VIRTIO_BLK(s->vdev);
 
-    if (!vblk->dataplane_started || s->stopping) {
+    if (s->stopping) {
         return;
     }
 
     /* Better luck next time. */
     if (s->disabled) {
         s->disabled = false;
-        vblk->dataplane_started = false;
         return;
     }
     s->stopping = true;
@@ -361,6 +358,5 @@ void virtio_blk_data_plane_stop(VirtIOBlockDataPlane *s)
     /* Clean up guest notifier (irq) */
     k->set_guest_notifiers(qbus->parent, 1, false);
 
-    vblk->dataplane_started = false;
     s->stopping = false;
 }
diff --git a/hw/block/virtio-blk.c b/hw/block/virtio-blk.c
index e04c8f5..34bae8e 100644
--- a/hw/block/virtio-blk.c
+++ b/hw/block/virtio-blk.c
@@ -590,6 +590,7 @@ static void virtio_blk_handle_output(VirtIODevice *vdev, 
VirtQueue *vq)
      * dataplane here instead of waiting for .set_status().
      */
     if (s->dataplane && !s->dataplane_started) {
+        s->dataplane_started = true;
         virtio_blk_data_plane_start(s->dataplane);
         return;
     }
@@ -658,8 +659,9 @@ static void virtio_blk_reset(VirtIODevice *vdev)
     aio_context_acquire(ctx);
     blk_drain(s->blk);
 
-    if (s->dataplane) {
+    if (s->dataplane && s->dataplane_started) {
         virtio_blk_data_plane_stop(s->dataplane);
+        s->dataplane_started = false;
     }
     aio_context_release(ctx);
 

Does it look better?

Paolo