Re: [PATCH] parisc: DMA API: return error instead of BUG_ON for dma ops on non dma devs

From: Helge Deller
Date: Wed Jul 05 2017 - 15:36:58 EST


Hi Christoph,

On 05.07.2017 20:57, Christoph Hellwig wrote:
> I've got a tree pending that removes DMA_ERROR_CODE, and it's been
> in linux-next for a while.

I had the parisc patch in for-next as well and didn't received
any warnings.

> While this won't compile-time conflict with this patch and will
> basically revert the effect.
>
> Can you please test the patch below and send it to Linus ASAP so that
> I can send the pull request for the dma-mapping tree?

I'll do that now.


> ---
> From 85942d54e2f0ad5f4b4e074ce2e271be17b31274 Mon Sep 17 00:00:00 2001
> From: Christoph Hellwig <hch@xxxxxx>
> Date: Tue, 4 Jul 2017 19:55:06 -0700
> Subject: parisc: ->mapping_error
>
> DMA_ERROR_CODE already went away in linux-next, but parisc unfortunately
> added a new instance of it without any review as far as I can tell.

Can we please change this to something like
"Prepare parisc to get rid of DMA_ERROR_CODE tree-wide" ?
It's somewhat more neutral.

Helge

>
> Move the two iommu drivers to report errors through ->mapping_error.
>
> Signed-off-by: Christoph Hellwig <hch@xxxxxx>
> ---
> arch/parisc/include/asm/dma-mapping.h | 2 --
> drivers/parisc/ccio-dma.c | 10 +++++++++-
> drivers/parisc/sba_iommu.c | 10 +++++++++-
> 3 files changed, 18 insertions(+), 4 deletions(-)
>
> diff --git a/arch/parisc/include/asm/dma-mapping.h b/arch/parisc/include/asm/dma-mapping.h
> index 9a2a8956a695..2b16282add69 100644
> --- a/arch/parisc/include/asm/dma-mapping.h
> +++ b/arch/parisc/include/asm/dma-mapping.h
> @@ -20,8 +20,6 @@
> ** flush/purge and allocate "regular" cacheable pages for everything.
> */
>
> -#define DMA_ERROR_CODE (~(dma_addr_t)0)
> -
> #ifdef CONFIG_PA11
> extern const struct dma_map_ops pcxl_dma_ops;
> extern const struct dma_map_ops pcx_dma_ops;
> diff --git a/drivers/parisc/ccio-dma.c b/drivers/parisc/ccio-dma.c
> index 56c93f096de9..6aa1e7f6672f 100644
> --- a/drivers/parisc/ccio-dma.c
> +++ b/drivers/parisc/ccio-dma.c
> @@ -110,6 +110,8 @@
> #define CMD_TLB_DIRECT_WRITE 35 /* IO_COMMAND for I/O TLB Writes */
> #define CMD_TLB_PURGE 33 /* IO_COMMAND to Purge I/O TLB entry */
>
> +#define CCIO_MAPPING_ERROR (~(dma_addr_t)0)
> +
> struct ioa_registers {
> /* Runway Supervisory Set */
> int32_t unused1[12];
> @@ -742,7 +744,7 @@ ccio_map_single(struct device *dev, void *addr, size_t size,
> BUG_ON(!dev);
> ioc = GET_IOC(dev);
> if (!ioc)
> - return DMA_ERROR_CODE;
> + return CCIO_MAPPING_ERROR;
>
> BUG_ON(size <= 0);
>
> @@ -1023,6 +1025,11 @@ ccio_unmap_sg(struct device *dev, struct scatterlist *sglist, int nents,
> DBG_RUN_SG("%s() DONE (nents %d)\n", __func__, nents);
> }
>
> +static int ccio_mapping_error(struct device *dev, dma_addr_t dma_addr)
> +{
> + return dma_addr == CCIO_MAPPING_ERROR;
> +}
> +
> static const struct dma_map_ops ccio_ops = {
> .dma_supported = ccio_dma_supported,
> .alloc = ccio_alloc,
> @@ -1031,6 +1038,7 @@ static const struct dma_map_ops ccio_ops = {
> .unmap_page = ccio_unmap_page,
> .map_sg = ccio_map_sg,
> .unmap_sg = ccio_unmap_sg,
> + .mapping_error = ccio_mapping_error,
> };
>
> #ifdef CONFIG_PROC_FS
> diff --git a/drivers/parisc/sba_iommu.c b/drivers/parisc/sba_iommu.c
> index 87ad5fd6a7a2..4086f79d58d5 100644
> --- a/drivers/parisc/sba_iommu.c
> +++ b/drivers/parisc/sba_iommu.c
> @@ -93,6 +93,8 @@
>
> #define DEFAULT_DMA_HINT_REG 0
>
> +#define SBA_MAPPING_ERROR (~(dma_addr_t)0)
> +
> struct sba_device *sba_list;
> EXPORT_SYMBOL_GPL(sba_list);
>
> @@ -725,7 +727,7 @@ sba_map_single(struct device *dev, void *addr, size_t size,
>
> ioc = GET_IOC(dev);
> if (!ioc)
> - return DMA_ERROR_CODE;
> + return SBA_MAPPING_ERROR;
>
> /* save offset bits */
> offset = ((dma_addr_t) (long) addr) & ~IOVP_MASK;
> @@ -1083,6 +1085,11 @@ sba_unmap_sg(struct device *dev, struct scatterlist *sglist, int nents,
>
> }
>
> +static int sba_mapping_error(struct device *dev, dma_addr_t dma_addr)
> +{
> + return dma_addr == SBA_MAPPING_ERROR;
> +}
> +
> static const struct dma_map_ops sba_ops = {
> .dma_supported = sba_dma_supported,
> .alloc = sba_alloc,
> @@ -1091,6 +1098,7 @@ static const struct dma_map_ops sba_ops = {
> .unmap_page = sba_unmap_page,
> .map_sg = sba_map_sg,
> .unmap_sg = sba_unmap_sg,
> + .mapping_error = sba_mapping_error,
> };
>
>
>