From mboxrd@z Thu Jan 1 00:00:00 1970 From: will.deacon@arm.com (Will Deacon) Date: Wed, 26 Oct 2016 19:26:28 +0100 Subject: [PATCH] arm64: Remove pointless WARN_ON in DMA teardown In-Reply-To: <74f5ae2ead8bb8fa9fabcf88b5962885b29eb2d5.1477505971.git.robin.murphy@arm.com> References: <74f5ae2ead8bb8fa9fabcf88b5962885b29eb2d5.1477505971.git.robin.murphy@arm.com> Message-ID: <20161026182628.GI15216@arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Wed, Oct 26, 2016 at 07:19:31PM +0100, Robin Murphy wrote: > We expect arch_teardown_dma_ops() to be called very late in a device's > life, after it has been removed from its bus, and thus after the IOMMU > bus notifier has run. As such, even if this funny little check did make > sense, it's unlikely to achieve what it thinks it's trying to do anyway. > It's a residual trace of an earlier implementation which didn't belong > here from the start; belatedly snuff it out. > > Signed-off-by: Robin Murphy > --- > arch/arm64/mm/dma-mapping.c | 5 ----- > 1 file changed, 5 deletions(-) > > diff --git a/arch/arm64/mm/dma-mapping.c b/arch/arm64/mm/dma-mapping.c > index 5cd0a383b14b..290a84f3351f 100644 > --- a/arch/arm64/mm/dma-mapping.c > +++ b/arch/arm64/mm/dma-mapping.c > @@ -940,11 +940,6 @@ static void __iommu_setup_dma_ops(struct device *dev, u64 dma_base, u64 size, > > void arch_teardown_dma_ops(struct device *dev) > { > - struct iommu_domain *domain = iommu_get_domain_for_dev(dev); > - > - if (WARN_ON(domain)) > - iommu_detach_device(domain, dev); > - > dev->archdata.dma_ops = NULL; > } Acked-by: Will Deacon I guess Catalin will pick this up when he starts queueing things for 4.10. Will