Messages in this thread | | | Date | Mon, 8 Dec 2014 20:30:18 +0100 | From | David Hildenbrand <> | Subject | Re: [PATCH v1] CPU hotplug: active_reader not woken up in some cases - deadlock |
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> > active_writer is cleared while holding cpuhp_lock, so this should be safe, > > right? > > You lost me on that one. Don't we get to that piece of code precisely > because we don't hold any of the CPU-hotplug locks? If so, the > writer might well hold all the locks it needs, and might well change > cpu_hotplug.active_writer out from under us. > > What am I missing here? > > Thanx, Paul
I was missing that cpuhp_lock_* are simply lockdep anotations ... it's getting late :)
So you're right, we need to verify that we don't get a 0 on the second access.
Will send an updated version soon.
Thanks!
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