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

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Date:   Wed, 12 Jul 2023 10:58:47 -0700
From:   Dave Jiang <dave.jiang@...el.com>
To:     Fenghua Yu <fenghua.yu@...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



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?
> ---
> 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?

>   	memset(wq->name, 0, WQ_NAME_SIZE);
>   	wq->max_xfer_bytes = WQ_DEFAULT_MAX_XFER;
>   	idxd_wq_set_max_batch_size(idxd->data->type, wq, WQ_DEFAULT_MAX_BATCH);