Adding linux-snps and linux-arch mailing lists.
> Revert the clearing of __GFP_ZERO in dma_alloc_attrs and move it to
> dma_direct_alloc for now. While most common architectures always zero dma
> cohereny allocations (and x86 did so since day one) this is not documented
> and at least arc and s390 do not zero without the explicit __GFP_ZERO
> argument.
This patch fixed Ethernet issues on ARC HSDK.
https://www.spinics.net/lists/kernel/msg2762054.html
Tested-by: Evgeniy Didin <evgeniy.di...@synopsys.com>
> Fixes: 57bf5a8963f8 ("dma-mapping: clear harmful GFP_* flags in common code")
> Reported-by: Evgeniy Didin <evgeniy.di...@synopsys.com>
> Reported-by: Sebastian Ott <seb...@linux.vnet.ibm.com>
> Signed-off-by: Christoph Hellwig <h...@lst.de>
> ---
> include/linux/dma-mapping.h | 8 ++------
> lib/dma-direct.c | 3 +++
> 2 files changed, 5 insertions(+), 6 deletions(-)
>
> diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
> index eb9eab4ecd6d..12fedcba9a9a 100644
> --- a/include/linux/dma-mapping.h
> +++ b/include/linux/dma-mapping.h
> @@ -518,12 +518,8 @@ static inline void *dma_alloc_attrs(struct device *dev,
> size_t size,
> if (dma_alloc_from_dev_coherent(dev, size, dma_handle, &cpu_addr))
> return cpu_addr;
>
> - /*
> - * Let the implementation decide on the zone to allocate from, and
> - * decide on the way of zeroing the memory given that the memory
> - * returned should always be zeroed.
> - */
> - flag &= ~(__GFP_DMA | __GFP_DMA32 | __GFP_HIGHMEM | __GFP_ZERO);
> + /* let the implementation decide on the zone to allocate from: */
> + flag &= ~(__GFP_DMA | __GFP_DMA32 | __GFP_HIGHMEM);
>
> if (!arch_dma_alloc_attrs(&dev, &flag))
> return NULL;
> diff --git a/lib/dma-direct.c b/lib/dma-direct.c
> index 1277d293d4da..c0bba30fef0a 100644
> --- a/lib/dma-direct.c
> +++ b/lib/dma-direct.c
> @@ -59,6 +59,9 @@ void *dma_direct_alloc(struct device *dev, size_t size,
> dma_addr_t *dma_handle,
> struct page *page = NULL;
> void *ret;
>
> + /* we always manually zero the memory once we are done: */
> + gfp &= ~__GFP_ZERO;
> +
> /* GFP_DMA32 and GFP_DMA are no ops without the corresponding zones: */
> if (dev->coherent_dma_mask <= DMA_BIT_MASK(ARCH_ZONE_DMA_BITS))
> gfp |= GFP_DMA;
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