Kevin Wolf <kw...@redhat.com> wrote: > Am 05.09.2017 um 10:54 hat Fam Zheng geschrieben: >> On Tue, 09/05 10:44, Kevin Wolf wrote: >> > Am 30.08.2017 um 12:06 hat Fam Zheng geschrieben: >> > > This fixes the assertion due to op blockers added by BMDS: >> > > >> > > block.c:3248: bdrv_delete: Assertion `bdrv_op_blocker_is_empty(bs)' >> > > failed. >> > > >> > > Reproducer: simply start block migration and quit QEMU before it ends. >> > > >> > > Cc: qemu-sta...@nongnu.org >> > > Signed-off-by: Fam Zheng <f...@redhat.com> >> > > --- >> > > block.c | 2 ++ >> > > migration/block.c | 2 +- >> > > migration/block.h | 1 + >> > > stubs/Makefile.objs | 1 + >> > > stubs/block-migration.c | 6 ++++++ >> > > 5 files changed, 11 insertions(+), 1 deletion(-) >> > > create mode 100644 stubs/block-migration.c >> > > >> > > diff --git a/block.c b/block.c >> > > index 3308814bba..508a57274d 100644 >> > > --- a/block.c >> > > +++ b/block.c >> > > @@ -43,6 +43,7 @@ >> > > #include "qemu/cutils.h" >> > > #include "qemu/id.h" >> > > #include "qapi/util.h" >> > > +#include "migration/block.h" >> > > >> > > #ifdef CONFIG_BSD >> > > #include <sys/ioctl.h> >> > > @@ -3111,6 +3112,7 @@ static void bdrv_close(BlockDriverState *bs) >> > > >> > > void bdrv_close_all(void) >> > > { >> > > + block_migration_cleanup_bmds(); >> > > block_job_cancel_sync_all(); >> > > nbd_export_close_all(); >> > >> > This is before bdrv_drain_all(). Can't we still have a block migration >> > request in flight, whose callback will then dereference a stale pointer? >> >> You're right, bdrv_drain_all should be called first. > > Actually, looking a bit closer, what prevents the migration thread from > starting new requests even after bdrv_drain_all()? Maybe what we really > need to do is cancelling the migration before calling bdrv_close_all().
I was wondering *where* to put this call inside the migration cleanup code, but I got to the conclusion that I was not sure that the migration cancellation code got called when you just do a "quit". Later, Juan.