linux-kernel - Re: the select system call's implementation may have some bug in preempt kernel mode

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Message-ID: <alpine.LFD.2.00.0910090921530.9428@localhost.localdomain>
Date:	Fri, 9 Oct 2009 09:22:49 +0200 (CEST)
From:	Thomas Gleixner <tglx@...utronix.de>
To:	wu Jianfeng <stormplayer@...il.com>
cc:	linux-kernel@...r.kernel.org
Subject: Re: the select system call's implementation may have some bug in
 preempt kernel mode

On Fri, 9 Oct 2009, wu Jianfeng wrote:

> > Right, but that does not cause the task to be scheduled out for ever.
> 
> I don't know why ???
> the process state is TASK_INTERRUPTIBLE, and was scheduled out.
> 
> if no one wake up it or any signals received, it will sleep for ever.
> The process does't entered any file's wait queue at that point, so I
> am sure no one will wake up it.
> 
> Am i right?

No. Did you actually read, what I wrote further down ?
 
> > When the task is scheduled out at that point, it is not
> > deactivated. It is preempted, which means it stays on the run queue
> > despite of the TASK_INTERRUPTIBLE state and is scheduled back in later
> > on.

Thanks,

	tglx
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