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Re: [PATCH 03/44] dmaengine: ioat: don't use DMA_ERROR_CODE

From Alexander Duyck <alexander.duyck@gmail.com>
Newsgroups linux.kernel
Subject Re: [PATCH 03/44] dmaengine: ioat: don't use DMA_ERROR_CODE
Date 2017-06-16 22:50 +0200
Message-ID <tT6lQ-5cd-3@gated-at.bofh.it> (permalink)
References <tT40F-3II-1@gated-at.bofh.it> <tT4an-3MU-27@gated-at.bofh.it>
Organization linux.* mail to news gateway

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On Fri, Jun 16, 2017 at 11:10 AM, Christoph Hellwig <hch@lst.de> wrote:
> DMA_ERROR_CODE is not a public API and will go away.  Instead properly
> unwind based on the loop counter.
>
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> Acked-by: Dave Jiang <dave.jiang@intel.com>
> Acked-By: Vinod Koul <vinod.koul@intel.com>
> ---
>  drivers/dma/ioat/init.c | 24 +++++++-----------------
>  1 file changed, 7 insertions(+), 17 deletions(-)
>
> diff --git a/drivers/dma/ioat/init.c b/drivers/dma/ioat/init.c
> index 6ad4384b3fa8..ed8ed1192775 100644
> --- a/drivers/dma/ioat/init.c
> +++ b/drivers/dma/ioat/init.c
> @@ -839,8 +839,6 @@ static int ioat_xor_val_self_test(struct ioatdma_device *ioat_dma)
>                 goto free_resources;
>         }
>
> -       for (i = 0; i < IOAT_NUM_SRC_TEST; i++)
> -               dma_srcs[i] = DMA_ERROR_CODE;
>         for (i = 0; i < IOAT_NUM_SRC_TEST; i++) {
>                 dma_srcs[i] = dma_map_page(dev, xor_srcs[i], 0, PAGE_SIZE,
>                                            DMA_TO_DEVICE);
> @@ -910,8 +908,6 @@ static int ioat_xor_val_self_test(struct ioatdma_device *ioat_dma)
>
>         xor_val_result = 1;
>
> -       for (i = 0; i < IOAT_NUM_SRC_TEST + 1; i++)
> -               dma_srcs[i] = DMA_ERROR_CODE;
>         for (i = 0; i < IOAT_NUM_SRC_TEST + 1; i++) {
>                 dma_srcs[i] = dma_map_page(dev, xor_val_srcs[i], 0, PAGE_SIZE,
>                                            DMA_TO_DEVICE);
> @@ -965,8 +961,6 @@ static int ioat_xor_val_self_test(struct ioatdma_device *ioat_dma)
>         op = IOAT_OP_XOR_VAL;
>
>         xor_val_result = 0;
> -       for (i = 0; i < IOAT_NUM_SRC_TEST + 1; i++)
> -               dma_srcs[i] = DMA_ERROR_CODE;
>         for (i = 0; i < IOAT_NUM_SRC_TEST + 1; i++) {
>                 dma_srcs[i] = dma_map_page(dev, xor_val_srcs[i], 0, PAGE_SIZE,
>                                            DMA_TO_DEVICE);
> @@ -1017,18 +1011,14 @@ static int ioat_xor_val_self_test(struct ioatdma_device *ioat_dma)
>         goto free_resources;
>  dma_unmap:
>         if (op == IOAT_OP_XOR) {
> -               if (dest_dma != DMA_ERROR_CODE)
> -                       dma_unmap_page(dev, dest_dma, PAGE_SIZE,
> -                                      DMA_FROM_DEVICE);
> -               for (i = 0; i < IOAT_NUM_SRC_TEST; i++)
> -                       if (dma_srcs[i] != DMA_ERROR_CODE)
> -                               dma_unmap_page(dev, dma_srcs[i], PAGE_SIZE,
> -                                              DMA_TO_DEVICE);
> +               while (--i >= 0)
> +                       dma_unmap_page(dev, dma_srcs[i], PAGE_SIZE,
> +                                      DMA_TO_DEVICE);
> +               dma_unmap_page(dev, dest_dma, PAGE_SIZE, DMA_FROM_DEVICE);
>         } else if (op == IOAT_OP_XOR_VAL) {
> -               for (i = 0; i < IOAT_NUM_SRC_TEST + 1; i++)
> -                       if (dma_srcs[i] != DMA_ERROR_CODE)
> -                               dma_unmap_page(dev, dma_srcs[i], PAGE_SIZE,
> -                                              DMA_TO_DEVICE);
> +               while (--i >= 0)
> +                       dma_unmap_page(dev, dma_srcs[i], PAGE_SIZE,
> +                                      DMA_TO_DEVICE);

Wouldn't it make more sense to pull out the while loop and just call
dma_unmap_page on dest_dma if "op == IOAT_OP_XOR"? Odds are it is what
the compiler is already generating and will save a few lines of code
so what you end up with is something like:
    while (--i >= 0)
        dma_unmap_page(dev, dma_srcs[i], PAGE_SIZE, DMA_TO_DEVICE);
    if (op == IOAT_OP_XOR)
        dma_unmap_page(dev, dest_dma, PAGE_SIZE, DMA_FROM_DEVICE);

>         }
>  free_resources:
>         dma->device_free_chan_resources(dma_chan);
> --
> 2.11.0
>

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Thread

clean up and modularize arch dma_mapping interface V2 Christoph Hellwig <hch@lst.de> - 2017-06-16 20:20 +0200
  [PATCH 44/44] powerpc: merge __dma_set_mask into dma_set_mask Christoph Hellwig <hch@lst.de> - 2017-06-16 20:20 +0200
  [PATCH 38/44] arm: implement ->dma_supported instead of ->set_dma_mask Christoph Hellwig <hch@lst.de> - 2017-06-16 20:20 +0200
  [PATCH 36/44] dma-mapping: remove HAVE_ARCH_DMA_SUPPORTED Christoph Hellwig <hch@lst.de> - 2017-06-16 20:20 +0200
  [PATCH 42/44] powerpc/cell: use the dma_supported method for ops switching Christoph Hellwig <hch@lst.de> - 2017-06-16 20:20 +0200
    Re: [PATCH 42/44] powerpc/cell: use the dma_supported method for  ops switching Benjamin Herrenschmidt <benh@kernel.crashing.org> - 2017-06-17 23:00 +0200
      Re: [PATCH 42/44] powerpc/cell: use the dma_supported method for ops  switching Christoph Hellwig <hch@infradead.org> - 2017-06-18 09:20 +0200
        Re: [PATCH 42/44] powerpc/cell: use the dma_supported method for  ops switching Benjamin Herrenschmidt <benh@kernel.crashing.org> - 2017-06-18 12:00 +0200
  [PATCH 27/44] sparc: remove leon_dma_ops Christoph Hellwig <hch@lst.de> - 2017-06-16 20:20 +0200
  [PATCH 31/44] hexagon: remove arch-specific dma_supported implementation Christoph Hellwig <hch@lst.de> - 2017-06-16 20:20 +0200
  [PATCH 34/44] arm: remove arch specific dma_supported implementation Christoph Hellwig <hch@lst.de> - 2017-06-16 20:20 +0200
  [PATCH 29/44] dma-noop: remove dma_supported and mapping_error methods Christoph Hellwig <hch@lst.de> - 2017-06-16 20:20 +0200
  [PATCH 40/44] tile: remove dma_supported and mapping_error methods Christoph Hellwig <hch@lst.de> - 2017-06-16 20:20 +0200
  [PATCH 41/44] powerpc/cell: clean up fixed mapping dma_ops initialization Christoph Hellwig <hch@lst.de> - 2017-06-16 20:20 +0200
  [PATCH 33/44] openrisc: remove arch-specific dma_supported implementation Christoph Hellwig <hch@lst.de> - 2017-06-16 20:20 +0200
  [PATCH 39/44] xen-swiotlb: remove xen_swiotlb_set_dma_mask Christoph Hellwig <hch@lst.de> - 2017-06-16 20:20 +0200
  [PATCH 17/44] hexagon: switch to use ->mapping_error for error reporting Christoph Hellwig <hch@lst.de> - 2017-06-16 20:20 +0200
  [PATCH 35/44] x86: remove arch specific dma_supported implementation Christoph Hellwig <hch@lst.de> - 2017-06-16 20:20 +0200
  [PATCH 32/44] hexagon: remove the unused dma_is_consistent prototype Christoph Hellwig <hch@lst.de> - 2017-06-16 20:20 +0200
  [PATCH 13/44] openrisc: remove DMA_ERROR_CODE Christoph Hellwig <hch@lst.de> - 2017-06-16 20:20 +0200
  [PATCH 37/44] mips/loongson64: implement ->dma_supported instead of ->set_dma_mask Christoph Hellwig <hch@lst.de> - 2017-06-16 20:20 +0200
  [PATCH 15/44] xtensa: remove DMA_ERROR_CODE Christoph Hellwig <hch@lst.de> - 2017-06-16 20:20 +0200
  [PATCH 24/44] x86: remove DMA_ERROR_CODE Christoph Hellwig <hch@lst.de> - 2017-06-16 20:20 +0200
  [PATCH 28/44] sparc: remove arch specific dma_supported implementations Christoph Hellwig <hch@lst.de> - 2017-06-16 20:20 +0200
  [PATCH 02/44] ibmveth: properly unwind on init errors Christoph Hellwig <hch@lst.de> - 2017-06-16 20:20 +0200
  [PATCH 01/44] firmware/ivc: use dma_mapping_error Christoph Hellwig <hch@lst.de> - 2017-06-16 20:20 +0200
  [PATCH 43/44] dma-mapping: remove the set_dma_mask method Christoph Hellwig <hch@lst.de> - 2017-06-16 20:20 +0200
  [PATCH 30/44] dma-virt: remove dma_supported and mapping_error methods Christoph Hellwig <hch@lst.de> - 2017-06-16 20:20 +0200
  [PATCH 26/44] dma-mapping: remove DMA_ERROR_CODE Christoph Hellwig <hch@lst.de> - 2017-06-16 20:30 +0200
  [PATCH 16/44] arm64: remove DMA_ERROR_CODE Christoph Hellwig <hch@lst.de> - 2017-06-16 20:30 +0200
  [PATCH 21/44] powerpc: implement ->mapping_error Christoph Hellwig <hch@lst.de> - 2017-06-16 20:30 +0200
  [PATCH 14/44] sh: remove DMA_ERROR_CODE Christoph Hellwig <hch@lst.de> - 2017-06-16 20:30 +0200
  [PATCH 19/44] s390: implement ->mapping_error Christoph Hellwig <hch@lst.de> - 2017-06-16 20:30 +0200
  [PATCH 25/44] arm: implement ->mapping_error Christoph Hellwig <hch@lst.de> - 2017-06-16 20:30 +0200
  [PATCH 23/44] x86/calgary: implement ->mapping_error Christoph Hellwig <hch@lst.de> - 2017-06-16 20:30 +0200
  [PATCH 06/44] iommu/dma: don't rely on DMA_ERROR_CODE Christoph Hellwig <hch@lst.de> - 2017-06-16 20:30 +0200
    Re: [PATCH 06/44] iommu/dma: don't rely on DMA_ERROR_CODE Robin Murphy <robin.murphy@arm.com> - 2017-06-19 17:20 +0200
  [PATCH 18/44] iommu/amd: implement ->mapping_error Christoph Hellwig <hch@lst.de> - 2017-06-16 20:30 +0200
  [PATCH 20/44] sparc: implement ->mapping_error Christoph Hellwig <hch@lst.de> - 2017-06-16 20:30 +0200
  [PATCH 10/44] ia64: remove DMA_ERROR_CODE Christoph Hellwig <hch@lst.de> - 2017-06-16 20:30 +0200
  [PATCH 08/44] xen-swiotlb: implement ->mapping_error Christoph Hellwig <hch@lst.de> - 2017-06-16 20:30 +0200
  [PATCH 03/44] dmaengine: ioat: don't use DMA_ERROR_CODE Christoph Hellwig <hch@lst.de> - 2017-06-16 20:30 +0200
    Re: [PATCH 03/44] dmaengine: ioat: don't use DMA_ERROR_CODE Alexander Duyck <alexander.duyck@gmail.com> - 2017-06-16 22:50 +0200
      Re: [PATCH 03/44] dmaengine: ioat: don't use DMA_ERROR_CODE Christoph Hellwig <hch@infradead.org> - 2017-06-18 09:10 +0200
  [PATCH 04/44] drm/exynos: don't use DMA_ERROR_CODE Christoph Hellwig <hch@lst.de> - 2017-06-16 20:30 +0200
  [PATCH 09/44] c6x: remove DMA_ERROR_CODE Christoph Hellwig <hch@lst.de> - 2017-06-16 20:30 +0200
  [PATCH 07/44] xen-swiotlb: consolidate xen_swiotlb_dma_ops Christoph Hellwig <hch@lst.de> - 2017-06-16 20:30 +0200
  [PATCH 11/44] m32r: remove DMA_ERROR_CODE Christoph Hellwig <hch@lst.de> - 2017-06-16 20:30 +0200
  [PATCH 22/44] x86/pci-nommu: implement ->mapping_error Christoph Hellwig <hch@lst.de> - 2017-06-16 20:30 +0200
  [PATCH 12/44] microblaze: remove DMA_ERROR_CODE Christoph Hellwig <hch@lst.de> - 2017-06-16 20:30 +0200
  [PATCH 05/44] drm/armada: don't abuse DMA_ERROR_CODE Christoph Hellwig <hch@lst.de> - 2017-06-16 20:30 +0200

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