block: Fix bdrv_next() memory leak

The bdrv_next() users all leaked the BdrvNextIterator after completing
the iteration. Simply changing bdrv_next() to free the iterator before
returning NULL at the end of list doesn't work because some callers exit
the loop before looking at all BDSes.

This patch moves the BdrvNextIterator from the heap to the stack of
the caller and switches to a bdrv_first()/bdrv_next() interface for
initialising the iterator.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>

1 files changed, 13 insertions, 2 deletions

diff --git a/include/block/block.h b/include/block/block.h
index a8c15e36e7..770ca26c57 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -17,7 +17,6 @@ typedef struct BlockJob BlockJob;
 typedef struct BdrvChild BdrvChild;
 typedef struct BdrvChildRole BdrvChildRole;
 typedef struct BlockJobTxn BlockJobTxn;
-typedef struct BdrvNextIterator BdrvNextIterator;
 
 typedef struct BlockDriverInfo {
     /* in bytes, 0 if irrelevant */
@@ -402,7 +401,19 @@ BlockDriverState *bdrv_lookup_bs(const char *device,
                                  Error **errp);
 bool bdrv_chain_contains(BlockDriverState *top, BlockDriverState *base);
 BlockDriverState *bdrv_next_node(BlockDriverState *bs);
-BdrvNextIterator *bdrv_next(BdrvNextIterator *it, BlockDriverState **bs);
+
+typedef struct BdrvNextIterator {
+    enum {
+        BDRV_NEXT_BACKEND_ROOTS,
+        BDRV_NEXT_MONITOR_OWNED,
+    } phase;
+    BlockBackend *blk;
+    BlockDriverState *bs;
+} BdrvNextIterator;
+
+BlockDriverState *bdrv_first(BdrvNextIterator *it);
+BlockDriverState *bdrv_next(BdrvNextIterator *it);
+
 BlockDriverState *bdrv_next_monitor_owned(BlockDriverState *bs);
 int bdrv_is_encrypted(BlockDriverState *bs);
 int bdrv_key_required(BlockDriverState *bs);