Subject: Re: [PATCH V9 02/13] powerpc, perf: Change type of the bhrb_users variable

From: Anshuman Khandual <[email-masked]>
Date: Thu, 25 Jun 2015 18:21:21 +0530

On 06/25/2015 11:12 AM, Daniel Axtens wrote:
>> -	int				bhrb_users;
>> +	unsigned int			bhrb_users;
> 
> OK, so this is a good start.
> 
> A quick git grep for bhrb_users reveals this:
> perf/core-book3s.c:     WARN_ON_ONCE(cpuhw->bhrb_users < 0);
> 
> That occurs in power_pmu_bhrb_disable, immediately following a decrement
> of bhrb_users. Now that the test can never be true, this patch should
> change the function to check if bhrb_users is 0 before decrementing.

Sure. Would replace with 'WARN_ON_ONCE(!cpuhw->bhrb_users)' before
decrementing bhrb_users in the function.