| Message ID | 20171229081911.2802-31-hch@lst.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
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@lst.de> > --- > 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 ? > +} > + > static void *dma_direct_alloc(struct device *dev, size_t size, > dma_addr_t *dma_handle, gfp_t gfp, unsigned long attrs) > { > @@ -35,11 +40,29 @@ static void *dma_direct_alloc(struct device *dev, size_t size, > int page_order = get_order(size); > struct page *page = NULL; > > +again: > /* CMA can be used only in the context which permits sleeping */ > - if (gfpflags_allow_blocking(gfp)) > + if (gfpflags_allow_blocking(gfp)) { > page = dma_alloc_from_contiguous(dev, count, page_order, gfp); > + if (page && !dma_coherent_ok(dev, page_to_phys(page), size)) { > + dma_release_from_contiguous(dev, page, count); > + page = NULL; > + } > + } > if (!page) > page = alloc_pages_node(dev_to_node(dev), gfp, page_order); > + > + 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? Thanks Vladimir
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@lst.de> > > --- > > 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.
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; +} + static void *dma_direct_alloc(struct device *dev, size_t size, dma_addr_t *dma_handle, gfp_t gfp, unsigned long attrs) { @@ -35,11 +40,29 @@ static void *dma_direct_alloc(struct device *dev, size_t size, int page_order = get_order(size); struct page *page = NULL; +again: /* CMA can be used only in the context which permits sleeping */ - if (gfpflags_allow_blocking(gfp)) + if (gfpflags_allow_blocking(gfp)) { page = dma_alloc_from_contiguous(dev, count, page_order, gfp); + if (page && !dma_coherent_ok(dev, page_to_phys(page), size)) { + dma_release_from_contiguous(dev, page, count); + page = NULL; + } + } if (!page) page = alloc_pages_node(dev_to_node(dev), gfp, page_order); + + 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; + } + } + if (!page) return NULL;
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@lst.de> --- lib/dma-direct.c | 25 ++++++++++++++++++++++++- 1 file changed, 24 insertions(+), 1 deletion(-)