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From: Robin Murphy <robin.murphy@arm.com>
To: Christoph Hellwig <hch@lst.de>, iommu@lists.linux-foundation.org
Cc: David Rientjes <rientjes@google.com>
Subject: Re: [PATCH 07/11] dma-direct: fail allocations that can't be made coherent
Date: Mon, 6 Dec 2021 16:33:28 +0000	[thread overview]
Message-ID: <b0b70acc-20f7-67dc-042a-5a9ddf19e32c@arm.com> (raw)
In-Reply-To: <20211111065028.32761-8-hch@lst.de>

On 2021-11-11 06:50, Christoph Hellwig wrote:
> If the architecture can't remap or set an address uncached there is no way
> to fullfill a request for a coherent allocation.  Return NULL in that case.
> Note that this case currently does not happen, so this is a theoretical
> fixup and/or a preparation for eventually supporting platforms that
> can't support coherent allocations with the generic code.

Reviewed-by: Robin Murphy <robin.murphy@arm.com>

> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>   kernel/dma/direct.c | 5 +++--
>   1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c
> index f9658fe18498c..a13017656ecae 100644
> --- a/kernel/dma/direct.c
> +++ b/kernel/dma/direct.c
> @@ -233,8 +233,9 @@ void *dma_direct_alloc(struct device *dev, size_t size,
>   				return dma_direct_alloc_from_pool(dev, size,
>   						dma_handle, gfp);
>   		} else {
> -			if (IS_ENABLED(CONFIG_ARCH_HAS_DMA_SET_UNCACHED))
> -				set_uncached = true;
> +			if (!IS_ENABLED(CONFIG_ARCH_HAS_DMA_SET_UNCACHED))
> +				return NULL;
> +			set_uncached = true;
>   		}
>   	}
>   
> 
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  reply	other threads:[~2021-12-06 16:33 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-11-11  6:50 dma-direct fixes and cleanups v3 Christoph Hellwig
2021-11-11  6:50 ` [PATCH 01/11] dma-direct: factor out dma_set_{de,en}crypted helpers Christoph Hellwig
2021-11-11  6:50 ` [PATCH 02/11] dma-direct: don't call dma_set_decrypted for remapped allocations Christoph Hellwig
2021-11-11  6:50 ` [PATCH 03/11] dma-direct: always leak memory that can't be re-encrypted Christoph Hellwig
2021-12-06 16:32   ` Robin Murphy
2021-12-07 11:48     ` Christoph Hellwig
2021-11-11  6:50 ` [PATCH 04/11] dma-direct: clean up the remapping checks in dma_direct_alloc Christoph Hellwig
2021-12-06 16:33   ` Robin Murphy
2021-12-07 11:49     ` Christoph Hellwig
2021-12-07 12:43       ` Robin Murphy
2021-11-11  6:50 ` [PATCH 05/11] dma-direct: factor out a helper for DMA_ATTR_NO_KERNEL_MAPPING allocations Christoph Hellwig
2021-11-11  6:50 ` [PATCH 06/11] dma-direct: refactor the !coherent checks in dma_direct_alloc Christoph Hellwig
2021-12-06 16:33   ` Robin Murphy
2021-11-11  6:50 ` [PATCH 07/11] dma-direct: fail allocations that can't be made coherent Christoph Hellwig
2021-12-06 16:33   ` Robin Murphy [this message]
2021-11-11  6:50 ` [PATCH 08/11] dma-direct: warn if there is no pool for force unencrypted allocations Christoph Hellwig
2021-11-11  6:50 ` [PATCH 09/11] dma-direct: drop two CONFIG_DMA_RESTRICTED_POOL conditionals Christoph Hellwig
2021-11-11  6:50 ` [PATCH 10/11] dma-direct: factor the swiotlb code out of __dma_direct_alloc_pages Christoph Hellwig
2021-11-11  6:50 ` [PATCH 11/11] dma-direct: add a dma_direct_use_pool helper Christoph Hellwig
2021-12-08 15:44   ` Marek Szyprowski
2021-12-08 15:48     ` Christoph Hellwig
2021-11-16 11:31 ` dma-direct fixes and cleanups v3 Robin Murphy
2021-11-17  5:51   ` Christoph Hellwig

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