Messages in this thread |  | | Date | Thu, 13 Feb 2014 18:44:52 +0100 | From | Oleg Nesterov <> | Subject | Re: [PATCH 01/51] CPU hotplug: Provide lockless versions of callback registration functions |
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On 02/12, Srivatsa S. Bhat wrote: > > On 02/11/2014 10:45 PM, Oleg Nesterov wrote: > > > > I am a bit confused... If we do this, why we can't simply turn > > cpu_add_remove_lock into rw_semaphore?
[...snip...]
> cpu_notifier_register_begin(); | Run in parallel > | with similar phases > for_each_online_cpu(cpu) | from other subsystems. > init_cpu(cpu); | > > /* Updates the cpu notifier chain. */ > register_cpu_notifier(&foobar_cpu_notifier); ||| -- Must run serially
Ah indeed, we can't use a single lock, thanks. Perhaps we can simply add a spinlock_t which only protects cpu_chain though, but I am not sure and currently this is off-topic anyway.
Thanks,
Oleg.
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