From: Christoph Hellwig <hch@lst.de>
Date: Tue, 9 Jan 2018 23:40:57 +0100
Subject: dma-direct: retry allocations using GFP_DMA for small masks
Git-commit: 95f183916d4b0bc1943684948ecdd2469f1aa978
Patch-mainline: v4.16-rc1
References: jsc#SLE-6197 FATE#327012 bsc#1140559 LTC#173150
If an attempt to allocate memory succeeded, but isn't inside the
supported DMA mask, retry the allocation with GFP_DMA set as a
last resort.
Based on the x86 code, but an off by one error in what is now
dma_coherent_ok has been fixed vs the x86 code.
[ ptesarik: This is in fact a rewrite for dma-noop, taking only the
idea from the original commit. ]
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Petr Tesarik <ptesarik@suse.com>
---
lib/dma-noop.c | 16 ++++++++++++++++
1 file changed, 16 insertions(+)
--- a/lib/dma-noop.c
+++ b/lib/dma-noop.c
@@ -16,6 +16,11 @@
#define ARCH_ZONE_DMA_BITS 24
#endif
+static bool dma_coherent_ok(struct device *dev, phys_addr_t phys, size_t size)
+{
+ return phys_to_dma(dev, phys) + size - 1 <= dev->coherent_dma_mask;
+}
+
static void *dma_noop_alloc(struct device *dev, size_t size,
dma_addr_t *dma_handle, gfp_t gfp,
unsigned long attrs)
@@ -28,7 +33,18 @@ static void *dma_noop_alloc(struct devic
if (dev->coherent_dma_mask <= DMA_BIT_MASK(32) && !(gfp & GFP_DMA))
gfp |= GFP_DMA32;
+again:
ret = (void *)__get_free_pages(gfp, get_order(size));
+ if (ret && !dma_coherent_ok(dev, virt_to_phys(ret), size)) {
+ free_pages((unsigned long)ret, get_order(size));
+ ret = NULL;
+
+ if (dev->coherent_dma_mask < DMA_BIT_MASK(32) &&
+ !(gfp & GFP_DMA)) {
+ gfp = (gfp & ~GFP_DMA32) | GFP_DMA;
+ goto again;
+ }
+ }
if (ret)
*dma_handle = virt_to_phys(ret);
return ret;