block: Assert that drv->bdrv_child_perm is set in bdrv_child_perm()

There is no need to check for this because all block drivers that have
children implement bdrv_child_perm and all callers already ensure that
bs->drv is set.

Furthermore, if this check would fail then the callers would end up
with uninitialized values for nperm and nshared.

This patch replaces the check with an assertion.

Signed-off-by: Alberto Garcia <berto@igalia.com>
Message-id: 20190404112953.4058-1-berto@igalia.com
Signed-off-by: Max Reitz <mreitz@redhat.com>

1 files changed, 4 insertions, 5 deletions

diff --git a/block.c b/block.c
index 9ae5c0ed2f..7dc8fe289a 100644
--- a/block.c
+++ b/block.c
@@ -1743,11 +1743,10 @@ static void bdrv_child_perm(BlockDriverState *bs, BlockDriverState *child_bs,
                             uint64_t parent_perm, uint64_t parent_shared,
                             uint64_t *nperm, uint64_t *nshared)
 {
-    if (bs->drv && bs->drv->bdrv_child_perm) {
-        bs->drv->bdrv_child_perm(bs, c, role, reopen_queue,
-                                 parent_perm, parent_shared,
-                                 nperm, nshared);
-    }
+    assert(bs->drv && bs->drv->bdrv_child_perm);
+    bs->drv->bdrv_child_perm(bs, c, role, reopen_queue,
+                             parent_perm, parent_shared,
+                             nperm, nshared);
     /* TODO Take force_share from reopen_queue */
     if (child_bs && child_bs->force_share) {
         *nshared = BLK_PERM_ALL;