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Date: Tue, 17 Dec 2013 10:48:40 +0100
From: Peter Zijlstra <peterz@infradead.org>
To: Richard Guy Briggs <rgb@redhat.com>
Cc: Oleg Nesterov <oleg@redhat.com>, Eric Paris <eparis@redhat.com>,
        linux-kernel@vger.kernel.org, linux-audit@redhat.com,
        Andrew Morton <akpm@linux-foundation.org>,
        "Eric W. Biederman" <ebiederm@xmission.com>,
        "Serge E. Hallyn" <serge@hallyn.com>
Subject: Re: [PATCH 11/12] pid: rewrite task helper functions avoiding
 task->pid and task->tgid
Message-ID: <20131217094840.GP3694@twins.programming.kicks-ass.net>
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On Tue, Dec 17, 2013 at 10:34:42AM +0100, Peter Zijlstra wrote:
> On Mon, Dec 16, 2013 at 05:20:51PM -0500, Richard Guy Briggs wrote:
> 
>  >  static inline bool is_idle_task(const struct task_struct *p)
>  >  {
>  > -	return p->pid == 0;
>  > +	return task_pid(p) == &init_struct_pid;
>  >  }
> 
> > I'll stick with task_pid_nr(p) == 0.
> 
> We're going to probably switch to:
> 
>   return p->flags & PF_IDLE;
> 
> Soon, because people are playing silly tricks and want normal threads
> to temporarily appear to be the idle thread (idle time injection).

See http://marc.info/?l=linux-kernel&m=138548236506953&w=2 for more
context.