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SubjectRe: [PATCH v2 2/3] nvme: implement DMA_ATTR_NO_WARN

On Thu, 7 Jul 2016 09:45:08 -0300 Mauricio Faria De Oliveira wrote:
> Use the DMA_ATTR_NO_WARN attribute on dma_map_sg() calls of nvme driver.
>
> Signed-off-by: Mauricio Faria de Oliveira <mauricfo@linux.vnet.ibm.com>
> Reviewed-by: Gabriel Krisman Bertazi <krisman@linux.vnet.ibm.com>
> ---
> Changelog:
> v2:
> - address warnings from checkpatch.pl (line wrapping and typos)
>
> drivers/nvme/host/pci.c | 12 ++++++++++--
> 1 file changed, 10 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
> index d1a8259..a7ccad8 100644
> --- a/drivers/nvme/host/pci.c
> +++ b/drivers/nvme/host/pci.c
> @@ -18,6 +18,7 @@
> #include <linux/blk-mq.h>
> #include <linux/cpu.h>
> #include <linux/delay.h>
> +#include <linux/dma-attrs.h>
> #include <linux/errno.h>
> #include <linux/fs.h>
> #include <linux/genhd.h>
> @@ -65,6 +66,8 @@ MODULE_PARM_DESC(use_cmb_sqes, "use controller's memory buffer for I/O SQes");
>
> static struct workqueue_struct *nvme_workq;
>
> +static DEFINE_DMA_ATTRS(nvme_dma_attrs);
> +
> struct nvme_dev;
> struct nvme_queue;
>
> @@ -498,7 +501,8 @@ static int nvme_map_data(struct nvme_dev *dev, struct request *req,
> goto out;
>
> ret = BLK_MQ_RQ_QUEUE_BUSY;
> - if (!dma_map_sg(dev->dev, iod->sg, iod->nents, dma_dir))
> + if (!dma_map_sg_attrs(dev->dev, iod->sg, iod->nents, dma_dir,
> + &nvme_dma_attrs))

This change is OK because the return value of nvme_map_data() is
BLK_MQ_RQ_QUEUE_BUSY, so the IO will be requeued.

> goto out;
>
> if (!nvme_setup_prps(dev, req, size))
> @@ -516,7 +520,8 @@ static int nvme_map_data(struct nvme_dev *dev, struct request *req,
> if (rq_data_dir(req))
> nvme_dif_remap(req, nvme_dif_prep);
>
> - if (!dma_map_sg(dev->dev, &iod->meta_sg, 1, dma_dir))
> + if (!dma_map_sg_attrs(dev->dev, &iod->meta_sg, 1, dma_dir,
> + &nvme_dma_attrs))

Here, I think the error messages should not be suppressed because
the return value of nvme_map_data() is BLK_MQ_RQ_QUEUE_ERROR, so
the IO returns as -EIO.

- Masayoshi Mizuma

> goto out_unmap;
> }
>
> @@ -2118,6 +2123,9 @@ static int __init nvme_init(void)
> result = pci_register_driver(&nvme_driver);
> if (result)
> destroy_workqueue(nvme_workq);
> +
> + dma_set_attr(DMA_ATTR_NO_WARN, &nvme_dma_attrs);
> +
> return result;
> }
>
>

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