block: Honor blk_set_aio_context() context requirements

The documentation for bdrv_set_aio_context_ignore() states this:

 * The caller must own the AioContext lock for the old AioContext of bs, but it
 * must not own the AioContext lock for new_context (unless new_context is the
 * same as the current context of bs).

As blk_set_aio_context() makes use of this function, this rule also
applies to it.

Fix all occurrences where this rule wasn't honored.

Suggested-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Sergio Lopez <slp@redhat.com>
Message-Id: <20201214170519.223781-2-slp@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Eric Blake <eblake@redhat.com>

1 files changed, 4 insertions, 2 deletions

diff --git a/hw/scsi/virtio-scsi.c b/hw/scsi/virtio-scsi.c
index 9690bc6..99ff261 100644
--- a/hw/scsi/virtio-scsi.c
+++ b/hw/scsi/virtio-scsi.c
@@ -849,15 +849,17 @@ static void virtio_scsi_hotplug(HotplugHandler *hotplug_dev, DeviceState *dev,
     VirtIODevice *vdev = VIRTIO_DEVICE(hotplug_dev);
     VirtIOSCSI *s = VIRTIO_SCSI(vdev);
     SCSIDevice *sd = SCSI_DEVICE(dev);
+    AioContext *old_context;
     int ret;
 
     if (s->ctx && !s->dataplane_fenced) {
         if (blk_op_is_blocked(sd->conf.blk, BLOCK_OP_TYPE_DATAPLANE, errp)) {
             return;
         }
-        virtio_scsi_acquire(s);
+        old_context = blk_get_aio_context(sd->conf.blk);
+        aio_context_acquire(old_context);
         ret = blk_set_aio_context(sd->conf.blk, s->ctx, errp);
-        virtio_scsi_release(s);
+        aio_context_release(old_context);
         if (ret < 0) {
             return;
         }