linux-kernel - Re: Problem with wake_up using real-time scheduling

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Date:	Thu, 02 Jul 2009 13:10:02 -0400
From:	Gregory Haskins <ghaskins@...ell.com>
To:	Zoltan Bus <zoltan.bus@...il.com>
CC:	linux-kernel@...r.kernel.org
Subject: Re: Problem with wake_up using real-time scheduling

Zoltan Bus wrote:
> Hello,
>
> I have a problem on kernel 2.6.26.3. I have a real-time task which
> uses the select system call to poll my audio driver. The sleeping task
> is waken up by wake_up() from an interrupt handler.
> The problem is, that the wake_up() function  sometimes does not wake
> up the task if real-time priority is used.
>
> The try_to_wake_up() returns from the out_running section, because of the check
>
>       if (p->se.on_rq)
>               goto out_running;
>
> There are no other tasks running when the poll function is called.
>
> Is this a known problem? Is it fixed somehow in newer versions?
> Unfortunately I do not have the possibility to change the newest kernel version.
> I am a newbie at linux, thank you very much for your help.
>
>   

That *should* work fine.  Can you post your code?

Regards,
-Greg


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