Messages in this thread |  | | Date | Tue, 10 Apr 2012 17:28:36 -0700 | | From | "Paul E. McKenney" <> | | Subject | Re: CPU Hotplug rework |
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On Tue, Apr 10, 2012 at 08:09:59PM -0400, Steven Rostedt wrote: > On Sat, 2012-04-07 at 01:22 +0530, Srivatsa S. Bhat wrote: > > > Wrapping only do_setup() within get/put_online_cpus() wouldn't serve our > > purpose, since the race with CPU Hotplug would still exist, just like > > before. So, let's consider what happens when we wrap both the functions > > within get/put_online_cpus(): > > > > get_online_cpus(); > > register_cpu_notifier(nb, mask); > > do_setup(mask); > > put_online_cpus(); > > > > Unfortunately this leads to an ABBA deadlock (see below). > > > > Just to throw out the stupid silly approach. > > What about creating a "__register_cpu_notifier()" that just does: > > int __ref __register_cpu_notifier(struct notifier_block *nb) > { > return raw_notifier_chain_register(&cpu_chain, nb); > } > > Also making cpu_maps_update_begin/done() global (and probably rename > them). > > and then in the above code do: > > cpu_maps_update_begin(); > __register_cpu_notifier(nb); > do_setup(); > cpu_maps_update_done(); > > > Just saying,
That does have some attractive properties, now that you mention it. ;-)
Thanx, Paul
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