Re: [PATCH] arm64/dma-mapping: Fix null-pointer check

From: Olav Haugan
Date: Mon Jun 12 2017 - 16:33:34 EST


On 17-06-12 13:29:04, Catalin Marinas wrote:
> On Sat, Jun 10, 2017 at 12:41:10PM -0700, Olav Haugan wrote:
> > @@ -149,6 +140,11 @@ static void *__dma_alloc(struct device *dev, size_t size,
> > bool coherent = is_device_dma_coherent(dev);
> > pgprot_t prot = __get_dma_pgprot(attrs, PAGE_KERNEL, false);
> >
> > + if (!dev) {
> > + WARN_ONCE(1, "Use an actual device structure for DMA allocation\n");
> > + return NULL;
> > + }
> > +
> > size = PAGE_ALIGN(size);
> >
> > if (!coherent && !gfpflags_allow_blocking(flags)) {
> > @@ -192,8 +188,13 @@ static void __dma_free(struct device *dev, size_t size,
> > void *vaddr, dma_addr_t dma_handle,
> > unsigned long attrs)
> > {
> > - void *swiotlb_addr = phys_to_virt(dma_to_phys(dev, dma_handle));
> > + void *swiotlb_addr;
> >
> > + if (!dev) {
> > + WARN_ONCE(1, "Use an actual device structure for DMA free\n");
> > + return;
> > + }
> > + swiotlb_addr = phys_to_virt(dma_to_phys(dev, dma_handle));
>
> I don't think we need the checks anymore. With commit 1dccb598df54
> ("arm64: simplify dma_get_ops") __generic_dma_ops() returns
> dummy_dma_ops when dev == NULL, so the above __dma_alloc/__dma_free
> functions would not be called.

Ah, you are right. I will remove the checks then! Thanks.

--
.Olav

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