* Peter Xu (pet...@redhat.com) wrote: > On Wed, Feb 27, 2019 at 04:49:00PM +0000, Dr. David Alan Gilbert (git) wrote: > > From: "Dr. David Alan Gilbert" <dgilb...@redhat.com> > > > > Currently we cleanup the migration object as we exit main after the > > main_loop finishes; however if there's a migration running things > > get messy and we can end up with the migration thread still trying > > to access freed structures. > > > > We now take a ref to the object around the migration thread itself, > > so the act of dropping the ref during exit doesn't cause us to lose > > the state until the thread quits. > > > > Cancelling the migration during migration also tries to get the thread > > to quit. > > > > We do this a bit earlier; so hopefully migration gets out of the way > > before all the devices etc are freed. > > So does it mean that even with the patch it's still possible the > migration thread will be accessing device structs that have already > been freed which can still crash QEMU?
Possibly yes; I'm not sure how to go to the next stage and stop that case; the consensus seems to be we don't want to explicitly block during the exit process, so doing a join on the migration thread doesn't seem to be wanted. Dave > Thanks, > > -- > Peter Xu -- Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK
