linux-kernel - Re: [PATCH 5/9] dmaengine: idxd: Allow DMA clients to empty the pending queue

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Message-ID: <006d3386-36ef-4c14-9373-7f6594a800f1@intel.com>
Date: Wed, 6 Aug 2025 10:17:02 -0700
From: Dave Jiang <dave.jiang@...el.com>
To: Vinicius Costa Gomes <vinicius.gomes@...el.com>,
 Vinod Koul <vkoul@...nel.org>, Dan Williams <dan.j.williams@...el.com>,
 Fenghua Yu <fenghuay@...dia.com>
Cc: dmaengine@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 5/9] dmaengine: idxd: Allow DMA clients to empty the
 pending queue



On 8/4/25 6:27 PM, Vinicius Costa Gomes wrote:
> Send a request to drain all pending commands from the hardware queue
> when the DMA clients request.
> 
> Signed-off-by: Vinicius Costa Gomes <vinicius.gomes@...el.com>
> ---
>  drivers/dma/idxd/dma.c | 10 ++++++++++
>  1 file changed, 10 insertions(+)
> 
> diff --git a/drivers/dma/idxd/dma.c b/drivers/dma/idxd/dma.c
> index dbecd699237e3ac5a73b49ed2097a897abc9a043..10356a00cbdfc2ddfeea629aa749c40e7eec0a56 100644
> --- a/drivers/dma/idxd/dma.c
> +++ b/drivers/dma/idxd/dma.c
> @@ -194,6 +194,15 @@ static void idxd_dma_release(struct dma_device *device)
>  	kfree(idxd_dma);
>  }
>  
> +static int idxd_dma_terminate_all(struct dma_chan *c)
> +{
> +	struct idxd_wq *wq = to_idxd_wq(c);
> +
> +	idxd_wq_drain(wq);

Definition in include/linux/dmaengine.h is "Aborts all transfers on a channel." So instead of drain, I think we need to abort and clean up all the pending descriptors on the irq list as well. Perhaps drain may be only for ->device_synchronize()?

DJ

> +
> +	return 0;
> +}
> +
>  int idxd_register_dma_device(struct idxd_device *idxd)
>  {
>  	struct idxd_dma_dev *idxd_dma;
> @@ -224,6 +233,7 @@ int idxd_register_dma_device(struct idxd_device *idxd)
>  	dma->device_issue_pending = idxd_dma_issue_pending;
>  	dma->device_alloc_chan_resources = idxd_dma_alloc_chan_resources;
>  	dma->device_free_chan_resources = idxd_dma_free_chan_resources;
> +	dma->device_terminate_all = idxd_dma_terminate_all;
>  
>  	rc = dma_async_device_register(dma);
>  	if (rc < 0) {
>