Messages in this thread | | | Date | Sun, 9 Dec 2012 21:57:33 +0100 | From | Oleg Nesterov <> | Subject | Re: [RFC PATCH v3 1/9] CPU hotplug: Provide APIs to prevent CPU offline from atomic context |
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On 12/07, Srivatsa S. Bhat wrote: > > 4. No deadlock possibilities > > Per-cpu locking is not the way to go if we want to have relaxed rules > for lock-ordering. Because, we can end up in circular-locking dependencies > as explained in https://lkml.org/lkml/2012/12/6/290
OK, but this assumes that, contrary to what Steven said, read-write-read deadlock is not possible when it comes to rwlock_t. So far I think this is true and we can't deadlock. Steven?
However. If this is true, then compared to preempt_disable/stop_machine livelock is possible. Probably this is fine, we have the same problem with get_online_cpus(). But if we can accept this fact I feel we can simmplify this somehow... Can't prove, only feel ;)
Oleg.
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