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Subject: Re: [RFC][PATCH v2 02/11] perf: core, add pmu register and lookup
 functions
From: Lin Ming <ming.m.lin@intel.com>
To: Cyrill Gorcunov <gorcunov@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>, Ingo Molnar <mingo@elte.hu>,
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Date: Wed, 19 May 2010 10:00:55 +0800
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On Wed, 2010-05-19 at 02:38 +0800, Cyrill Gorcunov wrote:
> On Wed, May 19, 2010 at 01:45:02AM +0000, Lin Ming wrote:
> ...
> > +int perf_event_register_pmu(struct pmu *pmu)
> > +{
> > +	struct pmu *tmp;
> > +	int ret = 1;
> > +
> > +	rcu_read_lock();
> > +	list_for_each_entry_rcu(tmp, &pmus, entry) {
> > +		if (tmp->id == pmu->id) {
> > +			ret = 0;
> > +			goto err;
> 
> Hi Ming, is it supposed to get out in locked state?
> I mean imbalanced rcu_read_lock somehow suspicicous ;)

Ah, yes, that's real bug.
I'll fix it.

Thanks for review.

> 
> > +		}
> > +	}
> > +	rcu_read_unlock();
> > +
> > +	spin_lock(&pmus_lock);
> > +	list_add_tail_rcu(&pmu->entry, &pmus);
> > +	spin_unlock(&pmus_lock);
> > +
> > +err:
> > +	return ret;
> > +}
> > +
> ...
> 
> 	-- Cyrill