On Wednesday, 26 of December 2007, Alan Stern wrote: > On Tue, 25 Dec 2007, Rafael J. Wysocki wrote: > > > > > Do we need to worry about the possibility that when the system wakes up > > > > from hibernation, the set of usable CPUs might be smaller than it was > > > > beforehand? > > > > > > This is possible in error conditions. > > > > > > > Is any special handling needed for this, or is it already accounted for? > > > > > > Hm, well. The cleanest thing would be to allow the drivers to remove the > > > device objects on CPU_UP_CANCELED_FROZEN, which means that we weren't able to > > > bring the CPU up during a resume, but still that will deadlock with > > > gregkh-driver-pm-acquire-device-locks-prior-to-suspending.patch. > > > > Hmm. In principle, device objects may be destroyed on CPU_UP_CANCELED_FROZEN > > without acquiring the device locks, since in fact we know these objects won't > > be accessed concurrently at that time (the locks are already held by the PM > > core, but the PM core is not going to actually access the devices before the > > subsequent resume). > > How about delaying the CPU_UP_CANCELED_FROZEN announcements until it's > really safe to send them out? That is, after all devices have been > resumed and the PM core no longer holds any of their locks. (Should > this be before or after tasks leave the freezer? -- I'm not sure.) > > So the idea is send appropriate announcements at the usual time for > CPUs that do come back up normally, and don't send anything right away > for CPUs that fail to come up. Just keep track of which ones failed, > and then later take care of them. However, we don't want to execute .resume() for device objects that correspond to the "dead" CPUs, so to a minimum we should remove them from the dpm_off list on CPU_UP_CANCELED_FROZEN. For this purpose, we can define a callback that will remove the device from dpm_off immediately and schedule its destruction after all devices have been resumed. Rafael _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
