From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx105.postini.com [74.125.245.105]) by kanga.kvack.org (Postfix) with SMTP id 8D2D46B0044 for ; Thu, 23 Aug 2012 03:33:23 -0400 (EDT) Received: from epcpsbgm2.samsung.com (mailout3.samsung.com [203.254.224.33]) by mailout3.samsung.com (Oracle Communications Messaging Server 7u4-24.01(7.0.4.24.0) 64bit (built Nov 17 2011)) with ESMTP id <0M97001H56B92P10@mailout3.samsung.com> for linux-mm@kvack.org; Thu, 23 Aug 2012 16:33:22 +0900 (KST) Received: from AMDC159 ([106.116.147.30]) by mmp1.samsung.com (Oracle Communications Messaging Server 7u4-24.01 (7.0.4.24.0) 64bit (built Nov 17 2011)) with ESMTPA id <0M97002YW6B6HG50@mmp1.samsung.com> for linux-mm@kvack.org; Thu, 23 Aug 2012 16:33:21 +0900 (KST) From: Marek Szyprowski References: <1345702229-9539-1-git-send-email-hdoyu@nvidia.com> <1345702229-9539-5-git-send-email-hdoyu@nvidia.com> In-reply-to: <1345702229-9539-5-git-send-email-hdoyu@nvidia.com> Subject: RE: [v2 4/4] ARM: dma-mapping: IOMMU allocates pages from atomic_pool with GFP_ATOMIC Date: Thu, 23 Aug 2012 09:33:05 +0200 Message-id: <013c01cd8101$8ccfa020$a66ee060$%szyprowski@samsung.com> MIME-version: 1.0 Content-type: text/plain; charset=us-ascii Content-transfer-encoding: 7bit Content-language: pl Sender: owner-linux-mm@kvack.org List-ID: To: 'Hiroshi Doyu' Cc: linux-arm-kernel@lists.infradead.org, linaro-mm-sig@lists.linaro.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, kyungmin.park@samsung.com, arnd@arndb.de, linux@arm.linux.org.uk, chunsang.jeong@linaro.org, vdumpa@nvidia.com, konrad.wilk@oracle.com, subashrp@gmail.com, minchan@kernel.org, pullip.cho@samsung.com Hi Hiroshi, On Thursday, August 23, 2012 8:10 AM Hiroshi Doyu wrote: > Makes use of the same atomic pool from DMA, and skips kernel page > mapping which can involve sleep'able operations at allocating a kernel > page table. > > Signed-off-by: Hiroshi Doyu > --- > arch/arm/mm/dma-mapping.c | 30 +++++++++++++++++++++++++----- > 1 files changed, 25 insertions(+), 5 deletions(-) > > diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c > index 7ab016b..433312a 100644 > --- a/arch/arm/mm/dma-mapping.c > +++ b/arch/arm/mm/dma-mapping.c > @@ -1063,7 +1063,6 @@ static struct page **__iommu_alloc_buffer(struct device *dev, size_t > size, > struct page **pages; > int count = size >> PAGE_SHIFT; > int array_size = count * sizeof(struct page *); > - int err; > > if ((array_size <= PAGE_SIZE) || (gfp & GFP_ATOMIC)) > pages = kzalloc(array_size, gfp); > @@ -1072,9 +1071,20 @@ static struct page **__iommu_alloc_buffer(struct device *dev, size_t > size, > if (!pages) > return NULL; > > - err = __alloc_fill_pages(&pages, count, gfp); > - if (err) > - goto error > + if (gfp & GFP_ATOMIC) { > + struct page *page; > + int i; > + void *addr = __alloc_from_pool(size, &page); > + if (!addr) > + goto error; > + > + for (i = 0; i < count; i++) > + pages[i] = page + i; > + } else { > + int err = __alloc_fill_pages(&pages, count, gfp); > + if (err) > + goto error; > + } > > return pages; > > @@ -1091,9 +1101,15 @@ static int __iommu_free_buffer(struct device *dev, struct page **pages, > size_t s > int count = size >> PAGE_SHIFT; > int array_size = count * sizeof(struct page *); > int i; > + > + if (__free_from_pool(page_address(pages[0]), size)) > + goto out; > + > for (i = 0; i < count; i++) > if (pages[i]) > __free_pages(pages[i], 0); > + > +out: > if ((array_size <= PAGE_SIZE) || > __in_atomic_pool(page_address(pages[0]), size)) > kfree(pages); > @@ -1221,6 +1237,9 @@ static void *arm_iommu_alloc_attrs(struct device *dev, size_t size, > if (*handle == DMA_ERROR_CODE) > goto err_buffer; > > + if (gfp & GFP_ATOMIC) > + return page_address(pages[0]); > + > if (dma_get_attr(DMA_ATTR_NO_KERNEL_MAPPING, attrs)) > return pages; > I've read the whole code and it looks that it starts to become a little spaghetti - there are too many places altered by those atomic changes and it is hard to follow the logic at the first sight. IMHO it will be better to add a following function: static void *__iommu_alloc_atomic(struct device *dev, size_t size, dma_addr_t *handle) { struct page *page, **pages; int count = size >> PAGE_SHIFT; int array_size = count * sizeof(struct page *); void *addr; int i; pages = kzalloc(array_size, gfp); if (!pages) return NULL; addr = __alloc_from_pool(size, &page); if (!addr) goto err_pool; for (i = 0; i < count; i++) pages[i] = page + i; *handle = __iommu_create_mapping(dev, pages, size); if (*handle == DMA_ERROR_CODE) goto err_mapping; return addr; err_mapping: __free_from_pool(addr, size); err_pool: kfree(pages); return NULL; } and then call it at the beginning of the arm_iommu_alloc_attrs(): if (gfp & GFP_ATOMIC) return __iommu_alloc_atomic(dev, size, handle); You should also add support for the allocation from atomic_pool to __iommu_get_pages() function to get dma_mmap() and dma_get_sgtable() working correctly. > @@ -1279,7 +1298,8 @@ void arm_iommu_free_attrs(struct device *dev, size_t size, void > *cpu_addr, > return; > } > > - if (!dma_get_attr(DMA_ATTR_NO_KERNEL_MAPPING, attrs)) { > + if (!dma_get_attr(DMA_ATTR_NO_KERNEL_MAPPING, attrs) || > + !__in_atomic_pool(cpu_addr, size)) { > unmap_kernel_range((unsigned long)cpu_addr, size); > vunmap(cpu_addr); > } Are you sure this one works? __iommu_get_pages() won't find pages array, because atomic allocations don't get their separate vm_struct area, so this check will be never reached. Maybe a __iommu_free_atomic() function would also make it safer and easier to understand. Best regards -- Marek Szyprowski Samsung Poland R&D Center -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org