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.Didin at synopsys.com> > Fixes: 57bf5a8963f8 ("dma-mapping: clear harmful GFP_* flags in common code") > Reported-by: Evgeniy Didin <Evgeniy.Didin at synopsys.com> > Reported-by: Sebastian Ott <sebott at linux.vnet.ibm.com> > Signed-off-by: Christoph Hellwig <hch at 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;
