linux-kernel - [RFC 2/4] ARM: dma-mapping: IOMMU allocates pages from pool with GFP

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Date:	Wed, 22 Aug 2012 13:20:28 +0300
From:	Hiroshi Doyu <hdoyu@...dia.com>
To:	Marek Szyprowski <m.szyprowski@...sung.com>
CC:	Hiroshi Doyu <hdoyu@...dia.com>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linaro-mm-sig@...ts.linaro.org" <linaro-mm-sig@...ts.linaro.org>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"kyungmin.park@...sung.com" <kyungmin.park@...sung.com>,
	"arnd@...db.de" <arnd@...db.de>,
	"linux@....linux.org.uk" <linux@....linux.org.uk>,
	"chunsang.jeong@...aro.org" <chunsang.jeong@...aro.org>,
	Krishna Reddy <vdumpa@...dia.com>,
	"konrad.wilk@...cle.com" <konrad.wilk@...cle.com>,
	"subashrp@...il.com" <subashrp@...il.com>,
	"minchan@...nel.org" <minchan@...nel.org>
Subject: [RFC 2/4] ARM: dma-mapping: IOMMU allocates pages from pool with GFP_ATOMIC

Makes use of the same atomic pool from DMA, and skips kernel page
mapping which can involves sleep'able operation at allocating a kernel
page table.

Signed-off-by: Hiroshi Doyu <hdoyu@...dia.com>
---
 arch/arm/mm/dma-mapping.c |   22 ++++++++++++++++++----
 1 files changed, 18 insertions(+), 4 deletions(-)

diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
index aec0c06..9260107 100644
--- a/arch/arm/mm/dma-mapping.c
+++ b/arch/arm/mm/dma-mapping.c
@@ -1028,7 +1028,6 @@ 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)
 		pages = kzalloc(array_size, gfp);
@@ -1037,9 +1036,20 @@ 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 err_out;
+
+		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;
 error:
@@ -1055,6 +1065,10 @@ 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))
+		return 0;
+
 	for (i = 0; i < count; i++)
 		if (pages[i])
 			__free_pages(pages[i], 0);
-- 
1.7.5.4

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