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Subject: Re: [PATCH] perf: Fix intel shared extra msr allocation
From: Peter Zijlstra <a.p.zijlstra@chello.nl>
To: "Yan, Zheng" <zheng.z.yan@linux.intel.com>
Cc: Stephane Eranian <eranian@google.com>,
        "Yan, Zheng" <zheng.z.yan@intel.com>, linux-kernel@vger.kernel.org
Date: Tue, 05 Jun 2012 12:14:31 +0200
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On Fri, 2012-06-01 at 22:11 +0800, Yan, Zheng wrote:
> 
> The real problem is from __intel_shared_reg_put_constraints(). it set
> reg->alloc to 0 

ok

> and decreases fake_cpuc->shared_regs->regs[reg->idx]'s
> reference count. 

So? That's fake state, who cares what its left in?

> Later when deleting the event,  put_constraints() will find
> reg->alloc is 0 and it won't decrease the shared msr's reference count.

OK, so the only problem is us setting reg->alloc to 0?