linux-kernel - Re: [PATCH v2] dmaengine: idxd: Clear PRS disable flag when disabling IDXD device

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Message-ID: <14f4e06e-8584-9dc3-ce85-b2491645b894@intel.com>
Date:   Wed, 12 Jul 2023 12:07:19 -0700
From:   Fenghua Yu <fenghua.yu@...el.com>
To:     Dave Jiang <dave.jiang@...el.com>, Vinod Koul <vkoul@...nel.org>
CC:     <dmaengine@...r.kernel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Tony Zhu <tony.zhu@...el.com>
Subject: Re: [PATCH v2] dmaengine: idxd: Clear PRS disable flag when disabling
 IDXD device

Hi, Dave,

On 7/12/23 10:58, Dave Jiang wrote:
> 
> 
> On 7/12/23 10:42, Fenghua Yu wrote:
>> Disabling IDXD device doesn't reset Page Request Service (PRS)
>> disable flag to its initial value 0. This may cause user confusion
>> because once PRS is disabled user will see PRS still remains the
>> previous setting (i.e. disabled) via sysfs interface even after the
>> device is disabled.
>>
>> To eliminate the confusion, reset PRS disable flag when the device
>> is disabled.
>>
>> Tested-by: Tony Zhu <tony.zhu@...el.com>
>> Signed-off-by: Fenghua Yu <fenghua.yu@...el.com>
> 
> Should there be a Fixes tag?

Will add a Fixes tag.

>> ---
>> v2:
>> - Fix Tony's email typo
>>
>>   drivers/dma/idxd/device.c | 1 +
>>   1 file changed, 1 insertion(+)
>>
>> diff --git a/drivers/dma/idxd/device.c b/drivers/dma/idxd/device.c
>> index 5abbcc61c528..71dfb2c13066 100644
>> --- a/drivers/dma/idxd/device.c
>> +++ b/drivers/dma/idxd/device.c
>> @@ -387,6 +387,7 @@ static void idxd_wq_disable_cleanup(struct idxd_wq 
>> *wq)
>>       clear_bit(WQ_FLAG_DEDICATED, &wq->flags);
>>       clear_bit(WQ_FLAG_BLOCK_ON_FAULT, &wq->flags);
>>       clear_bit(WQ_FLAG_ATS_DISABLE, &wq->flags);
>> +    clear_bit(WQ_FLAG_PRS_DISABLE, &wq->flags);
> 
> I wonder if it's better if we just do wq->flags = 0? I don't see any 
> bits we need to preserve. Do you?

wq->flags = 0 is better.

Thanks.

-Fenghua