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Re: [PATCH 5/5] MIPS/Perf-events: Use unsigned delta for right shift in

To: Will Deacon <will.deacon@arm.com>
Subject: Re: [PATCH 5/5] MIPS/Perf-events: Use unsigned delta for right shift in event update
From: Deng-Cheng Zhu <dengcheng.zhu@gmail.com>
Date: Fri, 19 Nov 2010 15:16:38 +0800
Cc: ralf@linux-mips.org, a.p.zijlstra@chello.nl, fweisbec@gmail.com, linux-mips@linux-mips.org, linux-kernel@vger.kernel.org, wuzhangjin@gmail.com, paulus@samba.org, mingo@elte.hu, acme@redhat.com
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Thanks. The commit you pointed out was also in this patch set (#3).

But I think the return value should stick to 0, not 1. Something out of my
consideration?


Deng-Cheng


2010/11/18 Will Deacon <will.deacon@arm.com>:
> On Thu, 2010-11-18 at 06:56 +0000, Deng-Cheng Zhu wrote:
>> Leverage the commit for ARM by Will Deacon:
>>
>> 446a5a8b1eb91a6990e5c8fe29f14e7a95b69132
>>         ARM: 6205/1: perf: ensure counter delta is treated as unsigned
>>
>> Signed-off-by: Deng-Cheng Zhu <dengcheng.zhu@gmail.com>
>> ---
>>  arch/mips/kernel/perf_event.c |    2 +-
>>  1 files changed, 1 insertions(+), 1 deletions(-)
>>
>> diff --git a/arch/mips/kernel/perf_event.c b/arch/mips/kernel/perf_event.c
>> index 345232a..0f1cdf5 100644
>> --- a/arch/mips/kernel/perf_event.c
>> +++ b/arch/mips/kernel/perf_event.c
>> @@ -169,7 +169,7 @@ static void mipspmu_event_update(struct perf_event 
>> *event,
>>         unsigned long flags;
>>         int shift = 64 - TOTAL_BITS;
>>         s64 prev_raw_count, new_raw_count;
>> -       s64 delta;
>> +       u64 delta;
>>
>>  again:
>>         prev_raw_count = local64_read(&hwc->prev_count);
>> --
>> 1.7.1
>
> Acked-by: Will Deacon <will.deacon@arm.com>
>
> You might also want to look at commit 65b4711f if you based
> the MIPS port on the old ARM code.
>
> Thanks,
>
> Will
>
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