On Tue, Jan 02, 2018 at 04:43:15PM +0000, Vladimir Murzin wrote:
On 29/12/17 08:18, Christoph Hellwig wrote:If we got back an allocation that wasn't inside the support coherent mask, retry the allocation using GFP_DMA. Based on the x86 code. Signed-off-by: Christoph Hellwig <hch@xxxxxx> --- lib/dma-direct.c | 25 ++++++++++++++++++++++++- 1 file changed, 24 insertions(+), 1 deletion(-) diff --git a/lib/dma-direct.c b/lib/dma-direct.c index ab81de3ac1d3..f8467cb3d89a 100644 --- a/lib/dma-direct.c +++ b/lib/dma-direct.c @@ -28,6 +28,11 @@ check_addr(struct device *dev, dma_addr_t dma_addr, size_t size, return true; } +static bool dma_coherent_ok(struct device *dev, phys_addr_t phys, size_t size) +{ + return phys_to_dma(dev, phys) + size <= dev->coherent_dma_mask;Shouldn't it be: phys_to_dma(dev, phys) + size - 1 <= dev->coherent_dma_mask ?
Yes, I think it should. The existing code was blindly copy and pasted from x86.
+ if (page && !dma_coherent_ok(dev, page_to_phys(page), size)) { + __free_pages(page, page_order); + page = NULL; + + if (dev->coherent_dma_mask < DMA_BIT_MASK(32) && + !(gfp & GFP_DMA)) { + gfp = (gfp & ~GFP_DMA32) | GFP_DMA; + goto again;Shouldn't we limit number of attempts?
We only retty once anyway, due to the !GFP_DMA check first and then ORing in GFP_DMA. -- To unsubscribe from this list: send the line "unsubscribe linux-m68k" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
