On 2012-10-23 14:12, Paolo Bonzini wrote: > Il 23/10/2012 14:04, Jan Kiszka ha scritto: >>>>>> >>>>>> So the stop_machine idea is thrown away? >>>> >>>> IIRC I convinced myself that it's just as bad. >> One tricky part with stop machine is that legacy code may trigger it >> while holding the BQL, does not expect to lose that lock even for a >> brief while, but synchronizing on other threads does require dropping >> the lock right now. Maybe an implementation detail, but at least a nasty >> one. > > But it would only be triggered by hot-unplug, no?
Once all code that adds/removes memory regions from within access handlers is converted. Legacy is biting, not necessarily the pure model. > That is already an > asynchronous action, so it is not a problem to delay the actual > stop_machine+qdev_free (and just that part!) to a bottom half or another > place when it is safe to drop the BQL. Jan -- Siemens AG, Corporate Technology, CT RTC ITP SDP-DE Corporate Competence Center Embedded Linux
