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Subject: Re: Inconsistency in changing the state of task ??
From: Robert Love <rml@tech9.net>
To: prash_t@softhome.net
Cc: linux-kernel@vger.kernel.org
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On Tue, 2003-03-04 at 03:36, prash_t@softhome.net wrote:

>      while browsing through fs/select.c file of 2.4.19, I came across two 
> DIFFERENT ways of changing the state of the current task in do_select(): 
> 
>             set_current_state = TASK_INTERRUPTIBLE;
>      AND    current->state = TASK_RUNNING; 
> 
> I am curious to know if the second line of code doesn't cause any problem in 
> SMP systems.  I also see the same situation in do_poll().

You normally want to use set_current_state(), which is a nice
abstraction and safe for SMP.

Sometimes it is safe to use __set_current_state(), which does not
provide a memory barrier.

The above open-coded line can be changed to
__set_current_state(TASK_RUNNING).

	Robert Love

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