linux-kernel - [PATCH 3.4 39/92] MIPS: dma-default: Fix 32-bit fall back to GFP

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Message-Id: <1460976397-5688-39-git-send-email-lizf@kernel.org>
Date:	Mon, 18 Apr 2016 18:45:44 +0800
From:	lizf@...nel.org
To:	stable@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, James Hogan <james.hogan@...tec.com>,
	Ralf Baechle <ralf@...ux-mips.org>, linux-mips@...ux-mips.org,
	Zefan Li <lizefan@...wei.com>
Subject: [PATCH 3.4 39/92] MIPS: dma-default: Fix 32-bit fall back to GFP_DMA

From: James Hogan <james.hogan@...tec.com>

3.4.112-rc1 review patch.  If anyone has any objections, please let me know.

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


commit 53960059d56ecef67d4ddd546731623641a3d2d1 upstream.

If there is a DMA zone (usually 24bit = 16MB I believe), but no DMA32
zone, as is the case for some 32-bit kernels, then massage_gfp_flags()
will cause DMA memory allocated for devices with a 32..63-bit
coherent_dma_mask to fall back to using __GFP_DMA, even though there may
only be 32-bits of physical address available anyway.

Correct that case to compare against a mask the size of phys_addr_t
instead of always using a 64-bit mask.

Signed-off-by: James Hogan <james.hogan@...tec.com>
Fixes: a2e715a86c6d ("MIPS: DMA: Fix computation of DMA flags from device's coherent_dma_mask.")
Cc: Ralf Baechle <ralf@...ux-mips.org>
Cc: linux-mips@...ux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/9610/
Signed-off-by: Ralf Baechle <ralf@...ux-mips.org>
Signed-off-by: Zefan Li <lizefan@...wei.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 0eea2d2..f395d5d 100644
--- a/arch/mips/mm/dma-default.c
+++ b/arch/mips/mm/dma-default.c
@@ -71,7 +71,7 @@ static gfp_t massage_gfp_flags(const struct device *dev, gfp_t gfp)
 	else
 #endif
 #if defined(CONFIG_ZONE_DMA) && !defined(CONFIG_ZONE_DMA32)
-	     if (dev->coherent_dma_mask < DMA_BIT_MASK(64))
+	     if (dev->coherent_dma_mask < DMA_BIT_MASK(sizeof(phys_addr_t) * 8))
 		dma_flag = __GFP_DMA;
 	else
 #endif
-- 
1.9.1