Add GRAPH_RDLOCK annotation to declare parallels_inactivate() have to hold
a reader lock for the graph because it calls
bdrv_get_device_or_node_name(), which accesses the parents list of a node.

Assert we are in the main thread in parallels_close() and guard the code
with GRAPH_RDLOCK_GUARD_MAINLOOP().

Signed-off-by: Alexander Ivanov <alexander.ivanov@virtuozzo.com>
---
 block/parallels.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/block/parallels.c b/block/parallels.c
index 2d82e8ff6a..4c2cb09e43 100644
--- a/block/parallels.c
+++ b/block/parallels.c
@@ -1465,7 +1465,7 @@ fail:
     return ret;
 }
 
-static int parallels_inactivate(BlockDriverState *bs)
+static int GRAPH_RDLOCK parallels_inactivate(BlockDriverState *bs)
 {
     BDRVParallelsState *s = bs->opaque;
     Error *err = NULL;
@@ -1491,10 +1491,13 @@ static int parallels_inactivate(BlockDriverState *bs)
     return ret;
 }
 
-static void parallels_close(BlockDriverState *bs)
+static void GRAPH_UNLOCKED parallels_close(BlockDriverState *bs)
 {
     BDRVParallelsState *s = bs->opaque;
 
+    GLOBAL_STATE_CODE();
+    GRAPH_RDLOCK_GUARD_MAINLOOP();
+
     if ((bs->open_flags & BDRV_O_RDWR) && !(bs->open_flags & BDRV_O_INACTIVE)) {
         parallels_inactivate(bs);
     }
-- 
2.34.1