linux-kernel - [PATCH] MIPS: Fix DMA contiguous allocation

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Message-ID: <1449569930-2118-1-git-send-email-qais.yousef@imgtec.com>
Date:	Tue, 8 Dec 2015 10:18:50 +0000
From:	Qais Yousef <qais.yousef@...tec.com>
To:	<linux-mips@...ux-mips.org>
CC:	<linux-mm@...ck.org>, <linux-kernel@...r.kernel.org>,
	<ralf@...ux-mips.org>, <akpm@...ux-foundation.org>,
	<mgorman@...hsingularity.net>, Qais Yousef <qais.yousef@...tec.com>
Subject: [PATCH] MIPS: Fix DMA contiguous allocation

Recent changes to how GFP_ATOMIC is defined seems to have broken the condition
to use mips_alloc_from_contiguous() in mips_dma_alloc_coherent().

I couldn't bottom out the exact change but I think it's this one

d0164adc89f6 (mm, page_alloc: distinguish between being unable to sleep,
unwilling to sleep and avoiding waking kswapd)

>From what I see GFP_ATOMIC has multiple bits set and the check for !(gfp
& GFP_ATOMIC) isn't enough. To verify if the flag is atomic we need to make
sure that (gfp & GFP_ATOMIC) == GFP_ATOMIC to verify that all bits rquired to
satisfy GFP_ATOMIC condition are set.

Signed-off-by: Qais Yousef <qais.yousef@...tec.com>
---
 arch/mips/mm/dma-default.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/mips/mm/dma-default.c b/arch/mips/mm/dma-default.c
index d8117be729a2..d6b8a1445a3a 100644
--- a/arch/mips/mm/dma-default.c
+++ b/arch/mips/mm/dma-default.c
@@ -145,7 +145,7 @@ static void *mips_dma_alloc_coherent(struct device *dev, size_t size,
 
 	gfp = massage_gfp_flags(dev, gfp);
 
-	if (IS_ENABLED(CONFIG_DMA_CMA) && !(gfp & GFP_ATOMIC))
+	if (IS_ENABLED(CONFIG_DMA_CMA) && ((gfp & GFP_ATOMIC) != GFP_ATOMIC))
 		page = dma_alloc_from_contiguous(dev,
 					count, get_order(size));
 	if (!page)
-- 
2.1.0

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