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Subject: Re: [RFC][PATCH 1/3] sched: Provide delayed wakeup list
From: Peter Zijlstra <a.p.zijlstra@chello.nl>
To: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>, Thomas Gleixner <tglx@linutronix.de>,
        linux-kernel@vger.kernel.org, Steven Rostedt <rostedt@goodmis.org>,
        Darren Hart <dvhart@linux.intel.com>,
        Manfred Spraul <manfred@colorfullife.com>,
        David Miller <davem@davemloft.net>, Mike Galbraith <efault@gmx.de>
Date: Wed, 14 Sep 2011 16:12:23 +0200
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On Wed, 2011-09-14 at 16:08 +0200, Eric Dumazet wrote:
> I dont understand why you make a get_task_struct() before the cmpxchg()
> and rollback. We certainly must hold a lock/mutex before calling
> wake_list_add()
> 
> It could be :
> 
> {
>         if (cmpxchg(&n->next, NULL, head->first))
>                 return;
>          
>         get_task_struct(p);
>         head->first = n;
> } 

You're quite right. No idea why I wrote it like that..