On Tue, Jan 14, 2014 at 11:13:46PM +0900, Akinobu Mita wrote: > Calling dma_alloc_coherent() with __GFP_ZERO must return zeroed memory. > > But when the contiguous memory allocator (CMA) is enabled on x86 and > the memory region is allocated by dma_alloc_from_contiguous(), it > doesn't return zeroed memory. Because dma_generic_alloc_coherent()
So why not fix it there to return zeroed out memory? > forgot to fill the memory region with zero if it was allocated by > dma_alloc_from_contiguous() > > Most implementations of dma_alloc_coherent() return zeroed memory > regardless of whether __GFP_ZERO is specified. So this fixes it by > unconditionally zeroing the allocated memory region. > > Cc: Marek Szyprowski <[email protected]> > Cc: Konrad Rzeszutek Wilk <[email protected]> > Cc: David Woodhouse <[email protected]> > Cc: Don Dutile <[email protected]> > Cc: Thomas Gleixner <[email protected]> > Cc: Ingo Molnar <[email protected]> > Cc: "H. Peter Anvin" <[email protected]> > Cc: Andi Kleen <[email protected]> > Cc: [email protected] > Cc: [email protected] > Signed-off-by: Akinobu Mita <[email protected]> > --- > New patch from this version > > arch/x86/kernel/pci-dma.c | 3 +-- > 1 file changed, 1 insertion(+), 2 deletions(-) > > diff --git a/arch/x86/kernel/pci-dma.c b/arch/x86/kernel/pci-dma.c > index 872079a..9644405 100644 > --- a/arch/x86/kernel/pci-dma.c > +++ b/arch/x86/kernel/pci-dma.c > @@ -97,7 +97,6 @@ void *dma_generic_alloc_coherent(struct device *dev, size_t > size, > > dma_mask = dma_alloc_coherent_mask(dev, flag); > > - flag |= __GFP_ZERO; > again: > page = NULL; > if (!(flag & GFP_ATOMIC)) > @@ -118,7 +117,7 @@ again: > > return NULL; > } > - > + memset(page_address(page), 0, size); > *dma_addr = addr; > return page_address(page); > } > -- > 1.8.3.2 > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
