Re: [PATCH 5/8] nvmet: pci-epf: Remove unnecessary dmaengine_terminate_sync() on each DMA transfer

Damien Le Moal
2025-12-09T06:56:48Z

On 12/9/25 2:09 AM, Frank Li wrote:
> dmaengine_terminate_sync() cancels all pending requests. Calling it for
> every DMA transfer is unnecessary and counterproductive. This function is
> generally intended for cleanup paths such as module removal, device close,
> or unbind operations.
>
> Remove the redundant calls.
>
> Signed-off-by: Frank Li <Frank.Li@nxp.com>
> ---
> This one also fix stress test failure after remove mutex and use new API
> dmaengine_prep_slave_sg_config().
> ---
> drivers/nvme/target/pci-epf.c | 2 --
> 1 file changed, 2 deletions(-)
>
> diff --git a/drivers/nvme/target/pci-epf.c b/drivers/nvme/target/pci-epf.c
> index 2e78397a7373a7d8ba67150f301f392123db88d1..85225a4f75b5bd7abb6897d064123766af021542 100644
> --- a/drivers/nvme/target/pci-epf.c
> +++ b/drivers/nvme/target/pci-epf.c
> @@ -420,8 +420,6 @@ static int nvmet_pci_epf_dma_transfer(struct nvmet_pci_epf *nvme_epf,
> ret = -EIO;
> }
>
> - dmaengine_terminate_sync(chan);

If the above dma_sync_wait failed, we better call this here as we have no idea
why we got the failure, no ?
For success case, we indeed may want to remove it.

> -
> unmap:
> dma_unmap_single(dma_dev, dma_addr, seg->length, dir);
>
>

--
Damien Le Moal
Western Digital Research