commit ede01e4635050a395eacd57b7d7fbea8ea208704
author Kevin Wolf <kwolf@redhat.com> Mon Sep 11 11:46:18 2023 +0200
committer Kevin Wolf <kwolf@redhat.com> Wed Sep 20 17:46:01 2023 +0200
tree 92113b8f904153f9ab38134a921b8993240c0946
parent 7f831d29e3d005e499b22c0591a26a33eb5c406d

block: Mark bdrv_root_unref_child() GRAPH_WRLOCK

Instead of taking the writer lock internally, require callers to already
hold it when calling bdrv_root_unref_child(). These callers will
typically already hold the graph lock once the locking work is
completed, which means that they can't call functions that take it
internally.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-ID: <20230911094620.45040-20-kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

block.c

diff --git a/block.c b/block.c
index 8e589bb..9ea8333 100644
--- a/block.c
+++ b/block.c
@@ -3268,7 +3268,6 @@
     BlockDriverState *child_bs = child->bs;
 
     GLOBAL_STATE_CODE();
-    bdrv_graph_wrlock(NULL);
     bdrv_replace_child_noperm(child, NULL);
     bdrv_child_free(child);
 
@@ -3288,8 +3287,7 @@
                                     NULL);
     }
 
-    bdrv_graph_wrunlock();
-    bdrv_unref(child_bs);
+    bdrv_schedule_unref(child_bs);
 }
 
 typedef struct BdrvSetInheritsFrom {
@@ -3366,8 +3364,10 @@
         return;
     }
 
+    bdrv_graph_wrlock(NULL);
     bdrv_unset_inherits_from(parent, child, NULL);
     bdrv_root_unref_child(child);
+    bdrv_graph_wrunlock();
 }