Re: [PATCH] VFS: br_write_lock locks on possible CPUs other thanonline CPUs

[Srivatsa S. Bhat]

On 12/20/2011 01:00 PM, mengcong wrote:

> On Tue, 2011-12-20 at 06:27 +0000, Al Viro wrote:
>> On Tue, Dec 20, 2011 at 10:26:05AM +0530, Srivatsa S. Bhat wrote:
>>> Oh, right, that has to be handled as well...
>>>
>>> Hmmm... How about registering a CPU hotplug notifier callback during lock init
>>> time, and then for every cpu that gets onlined (after we took a copy of the
>>> cpu_online_mask to work with), we see if that cpu is different from the ones
>>> we have already locked, and if it is, we lock it in the callback handler and
>>> update the locked_cpu_mask appropriately (so that we release the locks properly
>>> during the unlock operation).
>>>
>>> Handling the newly introduced race between the callback handler and lock-unlock
>>> code must not be difficult, I believe..
>>>
>>> Any loopholes in this approach? Or is the additional complexity just not worth
>>> it here?
>>
>> To summarize the modified variant of that approach hashed out on IRC:
>>
> On which IRC do you discuss?


#kernel on tinc.sekrit.org :-)

Regards,
Srivatsa S. Bhat

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