1 files changed, 2 insertions, 0 deletions
diff --git a/block/dmg.c b/block/dmg.c
index 64c3cce46a..111aeaecd9 100644
--- a/block/dmg.c
+++ b/block/dmg.c
@@ -28,6 +28,7 @@
 #include <zlib.h>
 
 typedef struct BDRVDMGState {
+    CoMutex lock;
     /* each chunk contains a certain number of sectors,
      * offsets[i] is the offset in the .dmg file,
      * lengths[i] is the length of the compressed chunk,
@@ -177,6 +178,7 @@ static int dmg_open(BlockDriverState *bs, int flags)
 
     s->current_chunk = s->n_chunks;
 
+    qemu_co_mutex_init(&s->lock);
     return 0;
 fail:
     return -1;