Re: [PATCHSET] workqueue: implement and use WQ_UNBOUND

[Tejun Heo <tj@kernel.org>]

Hello,

On 07/21/2010 05:25 PM, David Howells wrote:
>> Each gcwq keeps track of currently running works in a hash table and looks
>> whether the work in question is already executing before starting executing
>> it.  It's a bit complex but as a work_struct may be freed once execution
>> starts, the status needs to be tracked outside.
> 
> Thanks, that's what I wanted to know.
> 
> I presume this survives an executing work_struct being freed, reallocated and
> requeued before the address of the work_struct is removed from the hash table?

It will unnecessarily stall the execution of the new work if the last
work is still running but nothing will be broken correctness-wise.

> I can see at least one way of doing this: marking the work_struct address in
> the hash when the address becomes pending again so that the process of hash
> removal will cause the work_struct to be requeued automatically.

If I'm correctly understanding what you're saying, the code already
does about the same thing.

Thanks.

-- 
tejun