[Qemu-devel] [PATCH v2 2/2] virtio-scsi-dataplane: Call blk_set_aio_context within BQL

[Fam Zheng <famz@redhat.com>]

It's not safe to call blk_set_aio_context from outside BQL because of
the bdrv_drain_all there. Let's put it in the hotplug callback which
will be called by qdev device realization for each scsi device attached
to the bus.

Signed-off-by: Fam Zheng <famz@redhat.com>
---
 hw/scsi/virtio-scsi.c | 15 +++++++--------
 1 file changed, 7 insertions(+), 8 deletions(-)

diff --git a/hw/scsi/virtio-scsi.c b/hw/scsi/virtio-scsi.c
index 9e2c718..8c437dd 100644
--- a/hw/scsi/virtio-scsi.c
+++ b/hw/scsi/virtio-scsi.c
@@ -254,10 +254,8 @@ static int virtio_scsi_do_tmf(VirtIOSCSI *s, VirtIOSCSIReq *req)
     int target;
     int ret = 0;
 
-    if (s->dataplane_started && blk_get_aio_context(d->conf.blk) != s->ctx) {
-        aio_context_acquire(s->ctx);
-        blk_set_aio_context(d->conf.blk, s->ctx);
-        aio_context_release(s->ctx);
+    if (s->dataplane_started) {
+        assert(blk_get_aio_context(d->conf.blk) == s->ctx);
     }
     /* Here VIRTIO_SCSI_S_OK means "FUNCTION COMPLETE".  */
     req->resp.tmf.response = VIRTIO_SCSI_S_OK;
@@ -540,10 +538,8 @@ bool virtio_scsi_handle_cmd_req_prepare(VirtIOSCSI *s, VirtIOSCSIReq *req)
         virtio_scsi_complete_cmd_req(req);
         return false;
     }
-    if (s->dataplane_started && blk_get_aio_context(d->conf.blk) != s->ctx) {
-        aio_context_acquire(s->ctx);
-        blk_set_aio_context(d->conf.blk, s->ctx);
-        aio_context_release(s->ctx);
+    if (s->dataplane_started) {
+        assert(blk_get_aio_context(d->conf.blk) == s->ctx);
     }
     req->sreq = scsi_req_new(d, req->req.cmd.tag,
                              virtio_scsi_get_lun(req->req.cmd.lun),
@@ -767,6 +763,9 @@ static void virtio_scsi_hotplug(HotplugHandler *hotplug_dev, DeviceState *dev,
             return;
         }
         blk_op_block_all(sd->conf.blk, s->blocker);
+        aio_context_acquire(s->ctx);
+        blk_set_aio_context(sd->conf.blk, s->ctx);
+        aio_context_release(s->ctx);
     }
 
     if ((vdev->guest_features >> VIRTIO_SCSI_F_HOTPLUG) & 1) {
-- 
2.1.0