On Thu, Jun 30, 2016 at 04:45:52PM +0800, Changlong Xie wrote: > On 06/30/2016 04:25 PM, Fam Zheng wrote: > >On Thu, 06/30 16:01, Changlong Xie wrote: > >>Otherwise, we could never trigger assert(!bitmap->successor) > >> > >>Signed-off-by: Changlong Xie <xiecl.f...@cn.fujitsu.com> > >>--- > >> block/dirty-bitmap.c | 1 - > >> 1 file changed, 1 deletion(-) > >> > >>diff --git a/block/dirty-bitmap.c b/block/dirty-bitmap.c > >>index 4902ca5..e9df5ac 100644 > >>--- a/block/dirty-bitmap.c > >>+++ b/block/dirty-bitmap.c > >>@@ -131,7 +131,6 @@ int bdrv_dirty_bitmap_create_successor(BlockDriverState > >>*bs, > >> if (bdrv_dirty_bitmap_frozen(bitmap)) { > >> error_setg(errp, "Cannot create a successor for a bitmap that is " > >> "currently frozen"); > >>- return -1; > >> } > >> assert(!bitmap->successor); > > > >This is wrong. Then we will always trigger assert for a frozen bitmap. > > > > IMO, when it's a frozen bitmap, we will always return -1. So > "assert(!bitmap->successor)" is useless here, am i right? >
I don't see a path where the assert could trigger, so I would agree that the assert itself, while harmless, is not necessary (although it could be argued it is in place in case the code above it changes in a way that does not check bitmap->successor). That doesn't mean we want to try and trigger an assert, however! :) The error return is the proper error handling -- we don't expect that asserts should ever be encountered QEMU, if one happens that is a sign of a bug. Jeff