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Subject: Re: [tip:perfcounters/core] perf_counter: Use PID namespaces
 properly
From: Peter Zijlstra <a.p.zijlstra@chello.nl>
To: Oleg Nesterov <oleg@redhat.com>
Cc: linux-tip-commits@vger.kernel.org, linux-kernel@vger.kernel.org,
       acme@redhat.com, paulus@samba.org, hpa@zytor.com, mingo@redhat.com,
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       mingo@elte.hu
In-Reply-To: <20090602154816.GA15734@redhat.com>
References: <tip-709e50cf870e61745b39552044aa6c7c38e4f9e0@git.kernel.org>
	 <20090602154816.GA15734@redhat.com>
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Date: Tue, 02 Jun 2009 18:28:05 +0200
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On Tue, 2009-06-02 at 17:55 +0200, Oleg Nesterov wrote:
> On 06/02, tip-bot for Peter Zijlstra wrote:
> >
> > +static u32 perf_counter_pid(struct perf_counter *counter, struct task_struct *p)
> > +{
> > +	/*
> > +	 * only top level counters have the pid namespace they were created in
> > +	 */
> > +	if (counter->parent)
> > +		counter = counter->parent;
> > +
> > +	return task_tgid_nr_ns(p, counter->ns);
> > +}
> > +
> > +static u32 perf_counter_tid(struct perf_counter *counter, struct task_struct *p)
> > +{
> > +	/*
> > +	 * only top level counters have the pid namespace they were created in
> > +	 */
> > +	if (counter->parent)
> > +		counter = counter->parent;
> > +
> > +	return task_pid_nr_ns(p, counter->ns);
> 
> Perhaps this should be
> 
> 	return task_pid_nr_ns(p->group_leader);
> 
> ?

That seems to be exactly what task_tgid_nr_ns() does.

so  pid = task->group_leader->pids[PIDTYPE_PID].pid
and tid = task->pids[PIDTYPE_PID].pid

> > +		tid_entry.pid = perf_counter_pid(counter, current);
> > +		tid_entry.tid = perf_counter_tid(counter, current);
> 
> 
> Otherwise we seem to always report .pid == .tid

tgid vs pid, I don't think they end up being equal. Are they?