linux-kernel - Re: [PATCH v3] dmaengine: idxd: Clear PRS disable flag when disabling IDXD device

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Message-ID: <42f9e042-e404-2ecb-5e92-c3810671ecad@intel.com>
Date:   Wed, 12 Jul 2023 13:11:07 -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 v3] dmaengine: idxd: Clear PRS disable flag when disabling
 IDXD device



On 7/12/23 12:35, 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 user confusion, reset PRS disable flag to ensure that
> the PRS flag bit reflects correct state after the device is disabled.
> 
> Additionally, simplify the code by setting wq->flags to 0, which clears
> all flag bits, including any future additions.
> 
> Fixes: f2dc327131b5 ("dmaengine: idxd: add per wq PRS disable")
> Tested-by: Tony Zhu <tony.zhu@...el.com>
> Signed-off-by: Fenghua Yu <fenghua.yu@...el.com>

Reviewed-by: Dave Jiang <dave.jiang@...el.com>
> ---
> v3:
> - Add "Fixes" tag.
> - Set wq->flags to 0.
> 
> v2:
> - Fix Tony's email typo
> 
>   drivers/dma/idxd/device.c | 4 +---
>   1 file changed, 1 insertion(+), 3 deletions(-)
> 
> diff --git a/drivers/dma/idxd/device.c b/drivers/dma/idxd/device.c
> index 5abbcc61c528..9a15f0d12c79 100644
> --- a/drivers/dma/idxd/device.c
> +++ b/drivers/dma/idxd/device.c
> @@ -384,9 +384,7 @@ static void idxd_wq_disable_cleanup(struct idxd_wq *wq)
>   	wq->threshold = 0;
>   	wq->priority = 0;
>   	wq->enqcmds_retries = IDXD_ENQCMDS_RETRIES;
> -	clear_bit(WQ_FLAG_DEDICATED, &wq->flags);
> -	clear_bit(WQ_FLAG_BLOCK_ON_FAULT, &wq->flags);
> -	clear_bit(WQ_FLAG_ATS_DISABLE, &wq->flags);
> +	wq->flags = 0;
>   	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);