linux-kernel - [PATCH 3.8 11/81] x86: dma-mapping: fix GFP

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Message-Id: <1395767794-5012-12-git-send-email-kamal@canonical.com>
Date:	Tue, 25 Mar 2014 10:15:24 -0700
From:	Kamal Mostafa <kamal@...onical.com>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	kernel-team@...ts.ubuntu.com
Cc:	Marek Szyprowski <m.szyprowski@...sung.com>,
	Kamal Mostafa <kamal@...onical.com>
Subject: [PATCH 3.8 11/81] x86: dma-mapping: fix GFP_ATOMIC macro usage

3.8.13.20 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Marek Szyprowski <m.szyprowski@...sung.com>

commit c091c71ad2218fc50a07b3d1dab85783f3b77efd upstream.

GFP_ATOMIC is not a single gfp flag, but a macro which expands to the other
flags, where meaningful is the LACK of __GFP_WAIT flag. To check if caller
wants to perform an atomic allocation, the code must test for a lack of the
__GFP_WAIT flag. This patch fixes the issue introduced in v3.5-rc1.

Signed-off-by: Marek Szyprowski <m.szyprowski@...sung.com>
Signed-off-by: Kamal Mostafa <kamal@...onical.com>
---
 arch/x86/kernel/pci-dma.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/pci-dma.c b/arch/x86/kernel/pci-dma.c
index 872079a..f7d0672 100644
--- a/arch/x86/kernel/pci-dma.c
+++ b/arch/x86/kernel/pci-dma.c
@@ -100,8 +100,10 @@ void *dma_generic_alloc_coherent(struct device *dev, size_t size,
 	flag |= __GFP_ZERO;
 again:
 	page = NULL;
-	if (!(flag & GFP_ATOMIC))
+	/* CMA can be used only in the context which permits sleeping */
+	if (flag & __GFP_WAIT)
 		page = dma_alloc_from_contiguous(dev, count, get_order(size));
+	/* fallback */
 	if (!page)
 		page = alloc_pages_node(dev_to_node(dev), flag, get_order(size));
 	if (!page)
-- 
1.8.3.2

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