Subject: Re: Share Wait Queue between different modules ?
From: Steven Rostedt <rostedt@goodmis.org>
To: Dinesh Ahuja <mdlinux7@yahoo.co.in>
Cc: linux-kernel <linux-kernel@vger.kernel.org>
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Organization: Kihon Technologies
Date: Wed, 18 May 2005 11:45:03 -0400
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On Wed, 2005-05-18 at 16:02 +0100, Dinesh Ahuja wrote:
> Thanks Steven for answer.
> 
> Could please tell me know how to share wait queue
> between different modules and where will be pratical
> implementation of that case.

A wait_queue is where a task goes while waiting for some event. If you
want to share it among modules you first need to determine where the
wait queue would be declared.  If module A and module B use the same
wait queue, and module A has declared it. Then module B would be
dependent on module A.  Module A would also have to export the wait
queue via the EXPORT_SYMBOL macro.  Or, the wait queue can be declared
in the kernel itself and all modules can use it. 

As for a practical implementation for doing this, I'm not sure what you
are asking for since the question itself is quite abstract.  I haven't
needed to export a wait queue from one module to the next. The best I
can tell you is if one module supplies some functionality or driver for
some device that has a wait queue for some event, and another module
adds functionality or a sub system of the device that needs to have
tasks wait on the same event, then I guess that would be one case.

-- Steve


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