From: Robin Murphy <robin.murphy@arm.com>
To: Christoph Hellwig <hch@lst.de>, Will Deacon <will.deacon@arm.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: linux-arm-kernel@lists.infradead.org,
iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 03/10] swiotlb: do not panic on mapping failures
Date: Thu, 11 Oct 2018 19:06:31 +0100 [thread overview]
Message-ID: <ff847d0d-a2a1-65ba-ed18-aa71f632194d@arm.com> (raw)
In-Reply-To: <20181008080246.20543-4-hch@lst.de>
On 08/10/18 09:02, Christoph Hellwig wrote:
> All properly written drivers now have error handling in the
> dma_map_single / dma_map_page callers. As swiotlb_tbl_map_single already
> prints a useful warning when running out of swiotlb pool swace we can
> also remove swiotlb_full entirely as it serves no purpose now.
$ git grep -l 'dma_map_\(page\|single\)' drivers/ | wc -l
385
$ git grep -l dma_mapping_error drivers/ | wc -l
396
Close enough, to first approximation :D
I agree the other (non-fatal) warning seems sufficient, and frankly the
panic can be a bit of a pain for development sometimes.
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
> kernel/dma/swiotlb.c | 33 +--------------------------------
> 1 file changed, 1 insertion(+), 32 deletions(-)
>
> diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
> index 26d3af52956f..69bf305ee5f8 100644
> --- a/kernel/dma/swiotlb.c
> +++ b/kernel/dma/swiotlb.c
> @@ -761,34 +761,6 @@ static bool swiotlb_free_buffer(struct device *dev, size_t size,
> return true;
> }
>
> -static void
> -swiotlb_full(struct device *dev, size_t size, enum dma_data_direction dir,
> - int do_panic)
> -{
> - if (swiotlb_force == SWIOTLB_NO_FORCE)
> - return;
> -
> - /*
> - * Ran out of IOMMU space for this operation. This is very bad.
> - * Unfortunately the drivers cannot handle this operation properly.
> - * unless they check for dma_mapping_error (most don't)
> - * When the mapping is small enough return a static buffer to limit
> - * the damage, or panic when the transfer is too big.
> - */
> - dev_err_ratelimited(dev, "DMA: Out of SW-IOMMU space for %zu bytes\n",
> - size);
> -
> - if (size <= io_tlb_overflow || !do_panic)
> - return;
> -
> - if (dir == DMA_BIDIRECTIONAL)
> - panic("DMA: Random memory could be DMA accessed\n");
> - if (dir == DMA_FROM_DEVICE)
> - panic("DMA: Random memory could be DMA written\n");
> - if (dir == DMA_TO_DEVICE)
> - panic("DMA: Random memory could be DMA read\n");
> -}
> -
> /*
> * Map a single buffer of the indicated size for DMA in streaming mode. The
> * physical address to use is returned.
> @@ -817,10 +789,8 @@ dma_addr_t swiotlb_map_page(struct device *dev, struct page *page,
>
> /* Oh well, have to allocate and map a bounce buffer. */
> map = map_single(dev, phys, size, dir, attrs);
> - if (map == SWIOTLB_MAP_ERROR) {
> - swiotlb_full(dev, size, dir, 1);
> + if (map == SWIOTLB_MAP_ERROR)
> return __phys_to_dma(dev, io_tlb_overflow_buffer);
> - }
>
> dev_addr = __phys_to_dma(dev, map);
>
> @@ -948,7 +918,6 @@ swiotlb_map_sg_attrs(struct device *hwdev, struct scatterlist *sgl, int nelems,
> if (map == SWIOTLB_MAP_ERROR) {
> /* Don't panic here, we expect map_sg users
> to do proper error handling. */
> - swiotlb_full(hwdev, sg->length, dir, 0);
> attrs |= DMA_ATTR_SKIP_CPU_SYNC;
> swiotlb_unmap_sg_attrs(hwdev, sgl, i, dir,
> attrs);
>
next prev parent reply other threads:[~2018-10-11 18:06 UTC|newest]
Thread overview: 57+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-08 8:02 move swiotlb noncoherent dma support from arm64 to generic code V2 Christoph Hellwig
2018-10-08 8:02 ` [PATCH 01/10] swiotlb: remove a pointless comment Christoph Hellwig
2018-10-11 17:49 ` Robin Murphy
2018-10-19 0:09 ` Konrad Rzeszutek Wilk
2018-10-08 8:02 ` [PATCH 02/10] swiotlb: mark is_swiotlb_buffer static Christoph Hellwig
2018-10-11 17:54 ` Robin Murphy
2018-10-19 0:12 ` Konrad Rzeszutek Wilk
2018-10-08 8:02 ` [PATCH 03/10] swiotlb: do not panic on mapping failures Christoph Hellwig
2018-10-11 18:06 ` Robin Murphy [this message]
2018-10-19 0:18 ` Konrad Rzeszutek Wilk
2018-10-19 0:17 ` Konrad Rzeszutek Wilk
2018-10-19 6:04 ` Christoph Hellwig
2018-10-19 13:45 ` Konrad Rzeszutek Wilk
2018-10-08 8:02 ` [PATCH 04/10] swiotlb: remove the overflow buffer Christoph Hellwig
2018-10-11 18:19 ` Robin Murphy
2018-10-12 17:04 ` Catalin Marinas
2018-10-19 0:23 ` Konrad Rzeszutek Wilk
2018-10-08 8:02 ` [PATCH 05/10] swiotlb: merge swiotlb_unmap_page and unmap_single Christoph Hellwig
2018-10-18 17:44 ` Robin Murphy
2018-10-19 0:25 ` Konrad Rzeszutek Wilk
2018-10-08 8:02 ` [PATCH 06/10] swiotlb: use swiotlb_map_page in swiotlb_map_sg_attrs Christoph Hellwig
2018-10-18 17:53 ` Robin Murphy
2018-10-19 0:33 ` Konrad Rzeszutek Wilk
2018-11-07 1:27 ` John Stultz
2018-11-09 7:49 ` Christoph Hellwig
2018-11-09 16:37 ` Robin Murphy
2018-11-19 19:36 ` Robin Murphy
2018-11-20 9:22 ` Christoph Hellwig
2018-11-13 0:07 ` John Stultz
2018-11-13 0:26 ` John Stultz
2018-11-14 14:13 ` Christoph Hellwig
2018-11-14 16:12 ` Christoph Hellwig
2018-11-19 23:22 ` John Stultz
2018-11-20 9:25 ` Christoph Hellwig
2018-11-23 18:27 ` Will Deacon
2018-11-23 19:34 ` Robin Murphy
2018-11-26 19:31 ` Will Deacon
2018-10-08 8:02 ` [PATCH 07/10] swiotlb: refactor swiotlb_map_page Christoph Hellwig
2018-10-18 18:09 ` Robin Murphy
2018-10-19 0:37 ` Konrad Rzeszutek Wilk
2018-10-19 6:52 ` Christoph Hellwig
2018-10-19 13:46 ` Konrad Rzeszutek Wilk
2018-10-08 8:02 ` [PATCH 08/10] swiotlb: don't dip into swiotlb pool for coherent allocations Christoph Hellwig
2018-10-12 17:04 ` Catalin Marinas
2018-10-19 0:40 ` Konrad Rzeszutek Wilk
2018-10-19 16:45 ` Robin Murphy
2018-10-08 8:02 ` [PATCH 09/10] swiotlb: add support for non-coherent DMA Christoph Hellwig
2018-10-19 0:49 ` Konrad Rzeszutek Wilk
2018-10-22 17:11 ` Robin Murphy
2018-10-26 8:04 ` Christoph Hellwig
2018-10-26 9:59 ` Robin Murphy
2018-10-08 8:02 ` [PATCH 10/10] arm64: use the generic swiotlb_dma_ops Christoph Hellwig
2018-10-12 13:01 ` Robin Murphy
2018-10-12 14:40 ` Christoph Hellwig
2018-10-12 17:05 ` Catalin Marinas
2018-10-22 17:52 ` Robin Murphy
2018-10-26 12:44 ` Christoph Hellwig
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