[PATCH 13/40] vdpa: ref counting VhostVDPAShared

[Si-Wei Liu]

Subsequent patches attempt to release VhostVDPAShared resources,
for example iova tree to free and memory listener to unregister,
in vdpa_dev_cleanup(). Instead of checking against the vq index,
which is not always available in all of the callers, counting
the usage by reference. Then it'll be easy to free resource
upon the last deref.

Signed-off-by: Si-Wei Liu <si-wei.liu@oracle.com>
---
 include/hw/virtio/vhost-vdpa.h |  2 ++
 net/vhost-vdpa.c               | 14 ++++++++++----
 2 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/include/hw/virtio/vhost-vdpa.h b/include/hw/virtio/vhost-vdpa.h
index 63493ff..7b8d3bf 100644
--- a/include/hw/virtio/vhost-vdpa.h
+++ b/include/hw/virtio/vhost-vdpa.h
@@ -70,6 +70,8 @@ typedef struct vhost_vdpa_shared {
 
     /* Vdpa must send shadow addresses as IOTLB key for data queues, not GPA */
     bool shadow_data;
+
+    unsigned refcnt;
 } VhostVDPAShared;
 
 typedef struct vhost_vdpa {
diff --git a/net/vhost-vdpa.c b/net/vhost-vdpa.c
index aebaa53..a126e5c 100644
--- a/net/vhost-vdpa.c
+++ b/net/vhost-vdpa.c
@@ -236,11 +236,11 @@ static void vhost_vdpa_cleanup(NetClientState *nc)
         g_free(s->vhost_net);
         s->vhost_net = NULL;
     }
-    if (s->vhost_vdpa.index != 0) {
-        return;
+    if (--s->vhost_vdpa.shared->refcnt == 0) {
+        qemu_close(s->vhost_vdpa.shared->device_fd);
+        g_free(s->vhost_vdpa.shared);
     }
-    qemu_close(s->vhost_vdpa.shared->device_fd);
-    g_free(s->vhost_vdpa.shared);
+    s->vhost_vdpa.shared = NULL;
 }
 
 /** Dummy SetSteeringEBPF to support RSS for vhost-vdpa backend  */
@@ -1896,6 +1896,7 @@ static NetClientState *net_vhost_vdpa_init(NetClientState 
*peer,
         s->vhost_vdpa.shared->device_fd = vdpa_device_fd;
         s->vhost_vdpa.shared->iova_range = iova_range;
         s->vhost_vdpa.shared->shadow_data = svq;
+        s->vhost_vdpa.shared->refcnt++;
     } else if (!is_datapath) {
         s->cvq_cmd_out_buffer = mmap(NULL, vhost_vdpa_net_cvq_cmd_page_len(),
                                      PROT_READ | PROT_WRITE,
@@ -1910,6 +1911,7 @@ static NetClientState *net_vhost_vdpa_init(NetClientState 
*peer,
     }
     if (queue_pair_index != 0) {
         s->vhost_vdpa.shared = shared;
+        s->vhost_vdpa.shared->refcnt++;
     }
 
     ret = vhost_vdpa_add(nc, (void *)&s->vhost_vdpa, queue_pair_index, nvqs);
@@ -1928,6 +1930,10 @@ static NetClientState 
*net_vhost_vdpa_init(NetClientState *peer,
     return nc;
 
 err:
+    if (--s->vhost_vdpa.shared->refcnt == 0) {
+        g_free(s->vhost_vdpa.shared);
+    }
+    s->vhost_vdpa.shared = NULL;
     qemu_del_net_client(nc);
     return NULL;
 }
-- 
1.8.3.1