linux-kernel - Re: [PATCH] perf/smmuv3: Remove the leftover put

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Message-ID: <7dd33c04-3755-3eb6-d310-8e40207b16d9@huawei.com>
Date:   Wed, 11 Dec 2019 14:22:00 +0800
From:   Hanjun Guo <guohanjun@...wei.com>
To:     Will Deacon <will@...nel.org>
CC:     Mark Rutland <mark.rutland@....com>,
        Robin Murphy <robin.murphy@....com>,
        Shameer Kolothum <shameerali.kolothum.thodi@...wei.com>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] perf/smmuv3: Remove the leftover put_cpu() in error path

On 2019/12/10 22:10, Will Deacon wrote:
> On Tue, Dec 10, 2019 at 09:55:28PM +0800, Hanjun Guo wrote:
>> On 2019/12/10 21:24, Will Deacon wrote:
>>> On Tue, Dec 10, 2019 at 06:46:24PM +0800, Hanjun Guo wrote:
>>>> In smmu_pmu_probe(), there is put_cpu() in the error path,
>>>> which is wrong because we use raw_smp_processor_id() to
>>>> get the cpu ID, not get_cpu(), remove it.
>>>>
>>>> Signed-off-by: Hanjun Guo <guohanjun@...wei.com>
>>>> ---
>>>>  drivers/perf/arm_smmuv3_pmu.c | 1 -
>>>>  1 file changed, 1 deletion(-)
>>>>
>>>> diff --git a/drivers/perf/arm_smmuv3_pmu.c b/drivers/perf/arm_smmuv3_pmu.c
>>>> index 773128f..fd1d46a 100644
>>>> --- a/drivers/perf/arm_smmuv3_pmu.c
>>>> +++ b/drivers/perf/arm_smmuv3_pmu.c
>>>> @@ -834,7 +834,6 @@ static int smmu_pmu_probe(struct platform_device *pdev)
>>>>  out_unregister:
>>>>  	cpuhp_state_remove_instance_nocalls(cpuhp_state_num, &smmu_pmu->node);
>>>>  out_cpuhp_err:
>>>> -	put_cpu();
>>>>  	return err;
>>>
>>> Can we kill 'out_cpuhp_err' altogether then and just return err if we fail
>>> to add the hotplug instance?
>>
>> Makes sense, but I think we can go further to kill both 'out_cpuhp_err' and
>> 'out_register' as below [1], what do you think?
> 
> Although that's functionally correct, I'd prefer to keep out_unregister(),
> since it acts as good reminder to anybody extending this function in future
> that they need to unregister the hotplug instance on failure.

OK, I will add Robin's ACK and resend.

Thanks
Hanjun