[RFC] remove the ->mapping_error method from dma_map_ops

[RFC] remove the ->mapping_error method from dma_map_ops

[Christoph Hellwig]

Error reporting for the dma_map_single and dma_map_page operations is
currently a mess.  Both APIs directly return the dma_addr_t to be used for
the DMA, with a magic error escape that is specific to the instance and
checked by another method provided.  This has a few downsides:

 - the error check is easily forgotten and a __must_check marker doesn't
   help as the value always is consumed anyway
 - the error checking requires another indirect call, which have gotten
   incredibly expensive
 - a lot of code is wasted on implementing these methods

The historical reason for this is that people thought DMA mappings would
not fail when the API was created, which sounds like a really bad
assumption in retrospective, and then we tried to cram error handling
onto it later on.

There basically are two variants:  the error code is 0 because the
implementation will never return 0 as a valid DMA address, or the error
code is all-F as the implementation won't ever return an address that
high.  The old AMD GART is the only one not falling into these two camps
as it picks sort of a relative zero relative to where it is mapped.

The 0 return doesn't work for a lot of IOMMUs that start allocating
bus space from address zero, so we can't consolidate on that, but I think
we can move everyone to all-Fs, which the patch here does.  The reason
for that is that there is only one way to ever get this address: by
doing a 1-byte long, 1-byte aligned mapping, but all our mappings
are not only longer but generally aligned, and the mappings have to
keep at least the basic alignment.  Please try to poke holes into this
idea as it would simplify our logic a lot, and also allow to change
at least the not so commonly used yet dma_map_single_attrs and
dma_map_page_attrs to actually return an error code and further improve
the error handling flow in the drivers.

[PATCH 1/2] dma-mapping: remove ->mapping_error

[Christoph Hellwig]

There is no need to perform an indirect function call to check if a
DMA mapping resulted in an error, if we always return the last
possible dma address as the error code.  While that could in theory
be a valid DMAable region, it would have to assume we want to
support unaligned DMAs of size 1, which is rather pointless.

Instead simplify the whole machinery by using (~(dma_addr_t)0x0)
as the common error return.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/alpha/kernel/pci_iommu.c        | 10 ++-----
 arch/arm/common/dmabounce.c          | 12 +++------
 arch/arm/include/asm/dma-iommu.h     |  2 --
 arch/arm/mm/dma-mapping.c            | 39 +++++++++++-----------------
 arch/arm64/mm/dma-mapping.c          | 15 +++--------
 arch/ia64/hp/common/sba_iommu.c      |  8 +-----
 arch/ia64/sn/pci/pci_dma.c           |  8 +-----
 arch/mips/include/asm/jazzdma.h      |  6 -----
 arch/mips/jazz/jazzdma.c             | 16 ++++--------
 arch/powerpc/include/asm/iommu.h     |  3 ---
 arch/powerpc/kernel/dma-iommu.c      |  6 -----
 arch/powerpc/kernel/dma-swiotlb.c    |  1 -
 arch/powerpc/kernel/iommu.c          | 28 ++++++++++----------
 arch/powerpc/platforms/cell/iommu.c  |  1 -
 arch/powerpc/platforms/pseries/vio.c |  3 +--
 arch/s390/pci/pci_dma.c              | 18 ++++---------
 arch/sparc/kernel/iommu.c            | 12 +++------
 arch/sparc/kernel/iommu_common.h     |  2 --
 arch/sparc/kernel/pci_sun4v.c        | 14 +++-------
 arch/x86/kernel/amd_gart_64.c        | 19 ++++----------
 arch/x86/kernel/pci-calgary_64.c     | 24 ++++++-----------
 drivers/iommu/amd_iommu.c            | 18 ++++---------
 drivers/iommu/dma-iommu.c            | 23 ++++++----------
 drivers/iommu/intel-iommu.c          | 13 +++++-----
 drivers/parisc/ccio-dma.c            | 10 +------
 drivers/parisc/sba_iommu.c           | 10 +------
 drivers/pci/controller/vmd.c         |  6 -----
 drivers/xen/swiotlb-xen.c            | 12 ++-------
 include/linux/dma-direct.h           |  3 ---
 include/linux/dma-iommu.h            |  1 -
 include/linux/dma-mapping.h          | 12 ++++-----
 kernel/dma/direct.c                  |  8 +-----
 kernel/dma/swiotlb.c                 |  9 +++----
 33 files changed, 105 insertions(+), 267 deletions(-)

diff --git a/arch/alpha/kernel/pci_iommu.c b/arch/alpha/kernel/pci_iommu.c
index 46e08e0d9181..30339a0369ce 100644
--- a/arch/alpha/kernel/pci_iommu.c
+++ b/arch/alpha/kernel/pci_iommu.c
@@ -291,7 +291,7 @@ pci_map_single_1(struct pci_dev *pdev, void *cpu_addr, size_t size,
 	   use direct_map above, it now must be considered an error. */
 	if (! alpha_mv.mv_pci_tbi) {
 		printk_once(KERN_WARNING "pci_map_single: no HW sg\n");
-		return 0;
+		return DMA_MAPPING_ERROR;
 	}
 
 	arena = hose->sg_pci;
@@ -307,7 +307,7 @@ pci_map_single_1(struct pci_dev *pdev, void *cpu_addr, size_t size,
 	if (dma_ofs < 0) {
 		printk(KERN_WARNING "pci_map_single failed: "
 		       "could not allocate dma page tables\n");
-		return 0;
+		return DMA_MAPPING_ERROR;
 	}
 
 	paddr &= PAGE_MASK;
@@ -935,11 +935,6 @@ iommu_unbind(struct pci_iommu_arena *arena, long pg_start, long pg_count)
 	return 0;
 }
 
-static int alpha_pci_mapping_error(struct device *dev, dma_addr_t dma_addr)
-{
-	return dma_addr == 0;
-}
-
 const struct dma_map_ops alpha_pci_ops = {
 	.alloc			= alpha_pci_alloc_coherent,
 	.free			= alpha_pci_free_coherent,
@@ -947,7 +942,6 @@ const struct dma_map_ops alpha_pci_ops = {
 	.unmap_page		= alpha_pci_unmap_page,
 	.map_sg			= alpha_pci_map_sg,
 	.unmap_sg		= alpha_pci_unmap_sg,
-	.mapping_error		= alpha_pci_mapping_error,
 	.dma_supported		= alpha_pci_supported,
 };
 EXPORT_SYMBOL(alpha_pci_ops);
diff --git a/arch/arm/common/dmabounce.c b/arch/arm/common/dmabounce.c
index 9a92de63426f..5ba4622030ca 100644
--- a/arch/arm/common/dmabounce.c
+++ b/arch/arm/common/dmabounce.c
@@ -257,7 +257,7 @@ static inline dma_addr_t map_single(struct device *dev, void *ptr, size_t size,
 	if (buf == NULL) {
 		dev_err(dev, "%s: unable to map unsafe buffer %p!\n",
 		       __func__, ptr);
-		return ARM_MAPPING_ERROR;
+		return DMA_MAPPING_ERROR;
 	}
 
 	dev_dbg(dev, "%s: unsafe buffer %p (dma=%#x) mapped to %p (dma=%#x)\n",
@@ -327,7 +327,7 @@ static dma_addr_t dmabounce_map_page(struct device *dev, struct page *page,
 
 	ret = needs_bounce(dev, dma_addr, size);
 	if (ret < 0)
-		return ARM_MAPPING_ERROR;
+		return DMA_MAPPING_ERROR;
 
 	if (ret == 0) {
 		arm_dma_ops.sync_single_for_device(dev, dma_addr, size, dir);
@@ -336,7 +336,7 @@ static dma_addr_t dmabounce_map_page(struct device *dev, struct page *page,
 
 	if (PageHighMem(page)) {
 		dev_err(dev, "DMA buffer bouncing of HIGHMEM pages is not supported\n");
-		return ARM_MAPPING_ERROR;
+		return DMA_MAPPING_ERROR;
 	}
 
 	return map_single(dev, page_address(page) + offset, size, dir, attrs);
@@ -453,11 +453,6 @@ static int dmabounce_dma_supported(struct device *dev, u64 dma_mask)
 	return arm_dma_ops.dma_supported(dev, dma_mask);
 }
 
-static int dmabounce_mapping_error(struct device *dev, dma_addr_t dma_addr)
-{
-	return arm_dma_ops.mapping_error(dev, dma_addr);
-}
-
 static const struct dma_map_ops dmabounce_ops = {
 	.alloc			= arm_dma_alloc,
 	.free			= arm_dma_free,
@@ -472,7 +467,6 @@ static const struct dma_map_ops dmabounce_ops = {
 	.sync_sg_for_cpu	= arm_dma_sync_sg_for_cpu,
 	.sync_sg_for_device	= arm_dma_sync_sg_for_device,
 	.dma_supported		= dmabounce_dma_supported,
-	.mapping_error		= dmabounce_mapping_error,
 };
 
 static int dmabounce_init_pool(struct dmabounce_pool *pool, struct device *dev,
diff --git a/arch/arm/include/asm/dma-iommu.h b/arch/arm/include/asm/dma-iommu.h
index 6821f1249300..772f48ef84b7 100644
--- a/arch/arm/include/asm/dma-iommu.h
+++ b/arch/arm/include/asm/dma-iommu.h
@@ -9,8 +9,6 @@
 #include <linux/dma-debug.h>
 #include <linux/kref.h>
 
-#define ARM_MAPPING_ERROR		(~(dma_addr_t)0x0)
-
 struct dma_iommu_mapping {
 	/* iommu specific data */
 	struct iommu_domain	*domain;
diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
index 661fe48ab78d..2cfb17bad1e6 100644
--- a/arch/arm/mm/dma-mapping.c
+++ b/arch/arm/mm/dma-mapping.c
@@ -179,11 +179,6 @@ static void arm_dma_sync_single_for_device(struct device *dev,
 	__dma_page_cpu_to_dev(page, offset, size, dir);
 }
 
-static int arm_dma_mapping_error(struct device *dev, dma_addr_t dma_addr)
-{
-	return dma_addr == ARM_MAPPING_ERROR;
-}
-
 const struct dma_map_ops arm_dma_ops = {
 	.alloc			= arm_dma_alloc,
 	.free			= arm_dma_free,
@@ -197,7 +192,6 @@ const struct dma_map_ops arm_dma_ops = {
 	.sync_single_for_device	= arm_dma_sync_single_for_device,
 	.sync_sg_for_cpu	= arm_dma_sync_sg_for_cpu,
 	.sync_sg_for_device	= arm_dma_sync_sg_for_device,
-	.mapping_error		= arm_dma_mapping_error,
 	.dma_supported		= arm_dma_supported,
 };
 EXPORT_SYMBOL(arm_dma_ops);
@@ -217,7 +211,6 @@ const struct dma_map_ops arm_coherent_dma_ops = {
 	.get_sgtable		= arm_dma_get_sgtable,
 	.map_page		= arm_coherent_dma_map_page,
 	.map_sg			= arm_dma_map_sg,
-	.mapping_error		= arm_dma_mapping_error,
 	.dma_supported		= arm_dma_supported,
 };
 EXPORT_SYMBOL(arm_coherent_dma_ops);
@@ -774,7 +767,7 @@ static void *__dma_alloc(struct device *dev, size_t size, dma_addr_t *handle,
 	gfp &= ~(__GFP_COMP);
 	args.gfp = gfp;
 
-	*handle = ARM_MAPPING_ERROR;
+	*handle = DMA_MAPPING_ERROR;
 	allowblock = gfpflags_allow_blocking(gfp);
 	cma = allowblock ? dev_get_cma_area(dev) : false;
 
@@ -1217,7 +1210,7 @@ static inline dma_addr_t __alloc_iova(struct dma_iommu_mapping *mapping,
 	if (i == mapping->nr_bitmaps) {
 		if (extend_iommu_mapping(mapping)) {
 			spin_unlock_irqrestore(&mapping->lock, flags);
-			return ARM_MAPPING_ERROR;
+			return DMA_MAPPING_ERROR;
 		}
 
 		start = bitmap_find_next_zero_area(mapping->bitmaps[i],
@@ -1225,7 +1218,7 @@ static inline dma_addr_t __alloc_iova(struct dma_iommu_mapping *mapping,
 
 		if (start > mapping->bits) {
 			spin_unlock_irqrestore(&mapping->lock, flags);
-			return ARM_MAPPING_ERROR;
+			return DMA_MAPPING_ERROR;
 		}
 
 		bitmap_set(mapping->bitmaps[i], start, count);
@@ -1409,7 +1402,7 @@ __iommu_create_mapping(struct device *dev, struct page **pages, size_t size,
 	int i;
 
 	dma_addr = __alloc_iova(mapping, size);
-	if (dma_addr == ARM_MAPPING_ERROR)
+	if (dma_addr == DMA_MAPPING_ERROR)
 		return dma_addr;
 
 	iova = dma_addr;
@@ -1436,7 +1429,7 @@ __iommu_create_mapping(struct device *dev, struct page **pages, size_t size,
 fail:
 	iommu_unmap(mapping->domain, dma_addr, iova-dma_addr);
 	__free_iova(mapping, dma_addr, size);
-	return ARM_MAPPING_ERROR;
+	return DMA_MAPPING_ERROR;
 }
 
 static int __iommu_remove_mapping(struct device *dev, dma_addr_t iova, size_t size)
@@ -1497,7 +1490,7 @@ static void *__iommu_alloc_simple(struct device *dev, size_t size, gfp_t gfp,
 		return NULL;
 
 	*handle = __iommu_create_mapping(dev, &page, size, attrs);
-	if (*handle == ARM_MAPPING_ERROR)
+	if (*handle == DMA_MAPPING_ERROR)
 		goto err_mapping;
 
 	return addr;
@@ -1525,7 +1518,7 @@ static void *__arm_iommu_alloc_attrs(struct device *dev, size_t size,
 	struct page **pages;
 	void *addr = NULL;
 
-	*handle = ARM_MAPPING_ERROR;
+	*handle = DMA_MAPPING_ERROR;
 	size = PAGE_ALIGN(size);
 
 	if (coherent_flag  == COHERENT || !gfpflags_allow_blocking(gfp))
@@ -1546,7 +1539,7 @@ static void *__arm_iommu_alloc_attrs(struct device *dev, size_t size,
 		return NULL;
 
 	*handle = __iommu_create_mapping(dev, pages, size, attrs);
-	if (*handle == ARM_MAPPING_ERROR)
+	if (*handle == DMA_MAPPING_ERROR)
 		goto err_buffer;
 
 	if (attrs & DMA_ATTR_NO_KERNEL_MAPPING)
@@ -1696,10 +1689,10 @@ static int __map_sg_chunk(struct device *dev, struct scatterlist *sg,
 	int prot;
 
 	size = PAGE_ALIGN(size);
-	*handle = ARM_MAPPING_ERROR;
+	*handle = DMA_MAPPING_ERROR;
 
 	iova_base = iova = __alloc_iova(mapping, size);
-	if (iova == ARM_MAPPING_ERROR)
+	if (iova == DMA_MAPPING_ERROR)
 		return -ENOMEM;
 
 	for (count = 0, s = sg; count < (size >> PAGE_SHIFT); s = sg_next(s)) {
@@ -1739,7 +1732,7 @@ static int __iommu_map_sg(struct device *dev, struct scatterlist *sg, int nents,
 	for (i = 1; i < nents; i++) {
 		s = sg_next(s);
 
-		s->dma_address = ARM_MAPPING_ERROR;
+		s->dma_address = DMA_MAPPING_ERROR;
 		s->dma_length = 0;
 
 		if (s->offset || (size & ~PAGE_MASK) || size + s->length > max) {
@@ -1914,7 +1907,7 @@ static dma_addr_t arm_coherent_iommu_map_page(struct device *dev, struct page *p
 	int ret, prot, len = PAGE_ALIGN(size + offset);
 
 	dma_addr = __alloc_iova(mapping, len);
-	if (dma_addr == ARM_MAPPING_ERROR)
+	if (dma_addr == DMA_MAPPING_ERROR)
 		return dma_addr;
 
 	prot = __dma_info_to_prot(dir, attrs);
@@ -1926,7 +1919,7 @@ static dma_addr_t arm_coherent_iommu_map_page(struct device *dev, struct page *p
 	return dma_addr + offset;
 fail:
 	__free_iova(mapping, dma_addr, len);
-	return ARM_MAPPING_ERROR;
+	return DMA_MAPPING_ERROR;
 }
 
 /**
@@ -2020,7 +2013,7 @@ static dma_addr_t arm_iommu_map_resource(struct device *dev,
 	size_t len = PAGE_ALIGN(size + offset);
 
 	dma_addr = __alloc_iova(mapping, len);
-	if (dma_addr == ARM_MAPPING_ERROR)
+	if (dma_addr == DMA_MAPPING_ERROR)
 		return dma_addr;
 
 	prot = __dma_info_to_prot(dir, attrs) | IOMMU_MMIO;
@@ -2032,7 +2025,7 @@ static dma_addr_t arm_iommu_map_resource(struct device *dev,
 	return dma_addr + offset;
 fail:
 	__free_iova(mapping, dma_addr, len);
-	return ARM_MAPPING_ERROR;
+	return DMA_MAPPING_ERROR;
 }
 
 /**
@@ -2105,7 +2098,6 @@ const struct dma_map_ops iommu_ops = {
 	.map_resource		= arm_iommu_map_resource,
 	.unmap_resource		= arm_iommu_unmap_resource,
 
-	.mapping_error		= arm_dma_mapping_error,
 	.dma_supported		= arm_dma_supported,
 };
 
@@ -2124,7 +2116,6 @@ const struct dma_map_ops iommu_coherent_ops = {
 	.map_resource	= arm_iommu_map_resource,
 	.unmap_resource	= arm_iommu_unmap_resource,
 
-	.mapping_error		= arm_dma_mapping_error,
 	.dma_supported		= arm_dma_supported,
 };
 
diff --git a/arch/arm64/mm/dma-mapping.c b/arch/arm64/mm/dma-mapping.c
index a3ac26284845..4cc70029cf8d 100644
--- a/arch/arm64/mm/dma-mapping.c
+++ b/arch/arm64/mm/dma-mapping.c
@@ -282,7 +282,7 @@ static dma_addr_t __dummy_map_page(struct device *dev, struct page *page,
 				   enum dma_data_direction dir,
 				   unsigned long attrs)
 {
-	return 0;
+	return DMA_MAPPING_ERROR;
 }
 
 static void __dummy_unmap_page(struct device *dev, dma_addr_t dev_addr,
@@ -317,11 +317,6 @@ static void __dummy_sync_sg(struct device *dev,
 {
 }
 
-static int __dummy_mapping_error(struct device *hwdev, dma_addr_t dma_addr)
-{
-	return 1;
-}
-
 static int __dummy_dma_supported(struct device *hwdev, u64 mask)
 {
 	return 0;
@@ -339,7 +334,6 @@ const struct dma_map_ops dummy_dma_ops = {
 	.sync_single_for_device = __dummy_sync_single,
 	.sync_sg_for_cpu        = __dummy_sync_sg,
 	.sync_sg_for_device     = __dummy_sync_sg,
-	.mapping_error          = __dummy_mapping_error,
 	.dma_supported          = __dummy_dma_supported,
 };
 EXPORT_SYMBOL(dummy_dma_ops);
@@ -403,7 +397,7 @@ static void *__iommu_alloc_attrs(struct device *dev, size_t size,
 			return NULL;
 
 		*handle = iommu_dma_map_page(dev, page, 0, iosize, ioprot);
-		if (iommu_dma_mapping_error(dev, *handle)) {
+		if (*handle == DMA_MAPPING_ERROR) {
 			if (coherent)
 				__free_pages(page, get_order(size));
 			else
@@ -420,7 +414,7 @@ static void *__iommu_alloc_attrs(struct device *dev, size_t size,
 			return NULL;
 
 		*handle = iommu_dma_map_page(dev, page, 0, iosize, ioprot);
-		if (iommu_dma_mapping_error(dev, *handle)) {
+		if (*handle == DMA_MAPPING_ERROR) {
 			dma_release_from_contiguous(dev, page,
 						    size >> PAGE_SHIFT);
 			return NULL;
@@ -580,7 +574,7 @@ static dma_addr_t __iommu_map_page(struct device *dev, struct page *page,
 	dma_addr_t dev_addr = iommu_dma_map_page(dev, page, offset, size, prot);
 
 	if (!coherent && !(attrs & DMA_ATTR_SKIP_CPU_SYNC) &&
-	    !iommu_dma_mapping_error(dev, dev_addr))
+	    dev_addr != DMA_MAPPING_ERROR)
 		__dma_map_area(page_address(page) + offset, size, dir);
 
 	return dev_addr;
@@ -663,7 +657,6 @@ static const struct dma_map_ops iommu_dma_ops = {
 	.sync_sg_for_device = __iommu_sync_sg_for_device,
 	.map_resource = iommu_dma_map_resource,
 	.unmap_resource = iommu_dma_unmap_resource,
-	.mapping_error = iommu_dma_mapping_error,
 };
 
 static int __init __iommu_dma_init(void)
diff --git a/arch/ia64/hp/common/sba_iommu.c b/arch/ia64/hp/common/sba_iommu.c
index e8a93b07283e..5fca8ca85629 100644
--- a/arch/ia64/hp/common/sba_iommu.c
+++ b/arch/ia64/hp/common/sba_iommu.c
@@ -973,7 +973,7 @@ static dma_addr_t sba_map_page(struct device *dev, struct page *page,
 
 	pide = sba_alloc_range(ioc, dev, size);
 	if (pide < 0)
-		return 0;
+		return DMA_MAPPING_ERROR;
 
 	iovp = (dma_addr_t) pide << iovp_shift;
 
@@ -2170,11 +2170,6 @@ static int sba_dma_supported (struct device *dev, u64 mask)
 	return ((mask & 0xFFFFFFFFUL) == 0xFFFFFFFFUL);
 }
 
-static int sba_dma_mapping_error(struct device *dev, dma_addr_t dma_addr)
-{
-	return 0;
-}
-
 __setup("nosbagart", nosbagart);
 
 static int __init
@@ -2208,7 +2203,6 @@ const struct dma_map_ops sba_dma_ops = {
 	.map_sg			= sba_map_sg_attrs,
 	.unmap_sg		= sba_unmap_sg_attrs,
 	.dma_supported		= sba_dma_supported,
-	.mapping_error		= sba_dma_mapping_error,
 };
 
 void sba_dma_init(void)
diff --git a/arch/ia64/sn/pci/pci_dma.c b/arch/ia64/sn/pci/pci_dma.c
index 4ce4ee4ef9f2..b7d42e4edc1f 100644
--- a/arch/ia64/sn/pci/pci_dma.c
+++ b/arch/ia64/sn/pci/pci_dma.c
@@ -196,7 +196,7 @@ static dma_addr_t sn_dma_map_page(struct device *dev, struct page *page,
 
 	if (!dma_addr) {
 		printk(KERN_ERR "%s: out of ATEs\n", __func__);
-		return 0;
+		return DMA_MAPPING_ERROR;
 	}
 	return dma_addr;
 }
@@ -314,11 +314,6 @@ static int sn_dma_map_sg(struct device *dev, struct scatterlist *sgl,
 	return nhwentries;
 }
 
-static int sn_dma_mapping_error(struct device *dev, dma_addr_t dma_addr)
-{
-	return 0;
-}
-
 static u64 sn_dma_get_required_mask(struct device *dev)
 {
 	return DMA_BIT_MASK(64);
@@ -441,7 +436,6 @@ static struct dma_map_ops sn_dma_ops = {
 	.unmap_page		= sn_dma_unmap_page,
 	.map_sg			= sn_dma_map_sg,
 	.unmap_sg		= sn_dma_unmap_sg,
-	.mapping_error		= sn_dma_mapping_error,
 	.dma_supported		= sn_dma_supported,
 	.get_required_mask	= sn_dma_get_required_mask,
 };
diff --git a/arch/mips/include/asm/jazzdma.h b/arch/mips/include/asm/jazzdma.h
index d913439c738c..d13f940022d5 100644
--- a/arch/mips/include/asm/jazzdma.h
+++ b/arch/mips/include/asm/jazzdma.h
@@ -39,12 +39,6 @@ extern int vdma_get_enable(int channel);
 #define VDMA_PAGE(a)		((unsigned int)(a) >> 12)
 #define VDMA_OFFSET(a)		((unsigned int)(a) & (VDMA_PAGESIZE-1))
 
-/*
- * error code returned by vdma_alloc()
- * (See also arch/mips/kernel/jazzdma.c)
- */
-#define VDMA_ERROR		0xffffffff
-
 /*
  * VDMA pagetable entry description
  */
diff --git a/arch/mips/jazz/jazzdma.c b/arch/mips/jazz/jazzdma.c
index 4c41ed0a637e..6256d35dbf4d 100644
--- a/arch/mips/jazz/jazzdma.c
+++ b/arch/mips/jazz/jazzdma.c
@@ -104,12 +104,12 @@ unsigned long vdma_alloc(unsigned long paddr, unsigned long size)
 		if (vdma_debug)
 			printk("vdma_alloc: Invalid physical address: %08lx\n",
 			       paddr);
-		return VDMA_ERROR;	/* invalid physical address */
+		return DMA_MAPPING_ERROR;	/* invalid physical address */
 	}
 	if (size > 0x400000 || size == 0) {
 		if (vdma_debug)
 			printk("vdma_alloc: Invalid size: %08lx\n", size);
-		return VDMA_ERROR;	/* invalid physical address */
+		return DMA_MAPPING_ERROR;	/* invalid physical address */
 	}
 
 	spin_lock_irqsave(&vdma_lock, flags);
@@ -123,7 +123,7 @@ unsigned long vdma_alloc(unsigned long paddr, unsigned long size)
 		       first < VDMA_PGTBL_ENTRIES) first++;
 		if (first + pages > VDMA_PGTBL_ENTRIES) {	/* nothing free */
 			spin_unlock_irqrestore(&vdma_lock, flags);
-			return VDMA_ERROR;
+			return DMA_MAPPING_ERROR;
 		}
 
 		last = first + 1;
@@ -569,7 +569,7 @@ static void *jazz_dma_alloc(struct device *dev, size_t size,
 		return NULL;
 
 	*dma_handle = vdma_alloc(virt_to_phys(ret), size);
-	if (*dma_handle == VDMA_ERROR) {
+	if (*dma_handle == DMA_MAPPING_ERROR) {
 		dma_direct_free_pages(dev, size, ret, *dma_handle, attrs);
 		return NULL;
 	}
@@ -620,7 +620,7 @@ static int jazz_dma_map_sg(struct device *dev, struct scatterlist *sglist,
 			arch_sync_dma_for_device(dev, sg_phys(sg), sg->length,
 				dir);
 		sg->dma_address = vdma_alloc(sg_phys(sg), sg->length);
-		if (sg->dma_address == VDMA_ERROR)
+		if (sg->dma_address == DMA_MAPPING_ERROR)
 			return 0;
 		sg_dma_len(sg) = sg->length;
 	}
@@ -674,11 +674,6 @@ static void jazz_dma_sync_sg_for_cpu(struct device *dev,
 		arch_sync_dma_for_cpu(dev, sg_phys(sg), sg->length, dir);
 }
 
-static int jazz_dma_mapping_error(struct device *dev, dma_addr_t dma_addr)
-{
-	return dma_addr == VDMA_ERROR;
-}
-
 const struct dma_map_ops jazz_dma_ops = {
 	.alloc			= jazz_dma_alloc,
 	.free			= jazz_dma_free,
@@ -692,6 +687,5 @@ const struct dma_map_ops jazz_dma_ops = {
 	.sync_sg_for_device	= jazz_dma_sync_sg_for_device,
 	.dma_supported		= dma_direct_supported,
 	.cache_sync		= arch_dma_cache_sync,
-	.mapping_error		= jazz_dma_mapping_error,
 };
 EXPORT_SYMBOL(jazz_dma_ops);
diff --git a/arch/powerpc/include/asm/iommu.h b/arch/powerpc/include/asm/iommu.h
index 35db0cbc9222..5c45e702133c 100644
--- a/arch/powerpc/include/asm/iommu.h
+++ b/arch/powerpc/include/asm/iommu.h
@@ -142,9 +142,6 @@ int get_iommu_order(unsigned long size, struct iommu_table *tbl)
 struct scatterlist;
 
 #ifdef CONFIG_PPC64
-
-#define IOMMU_MAPPING_ERROR		(~(dma_addr_t)0x0)
-
 static inline void set_iommu_table_base(struct device *dev,
 					struct iommu_table *base)
 {
diff --git a/arch/powerpc/kernel/dma-iommu.c b/arch/powerpc/kernel/dma-iommu.c
index f9fe2080ceb9..5ebacf0fe41a 100644
--- a/arch/powerpc/kernel/dma-iommu.c
+++ b/arch/powerpc/kernel/dma-iommu.c
@@ -106,11 +106,6 @@ static u64 dma_iommu_get_required_mask(struct device *dev)
 	return mask;
 }
 
-int dma_iommu_mapping_error(struct device *dev, dma_addr_t dma_addr)
-{
-	return dma_addr == IOMMU_MAPPING_ERROR;
-}
-
 struct dma_map_ops dma_iommu_ops = {
 	.alloc			= dma_iommu_alloc_coherent,
 	.free			= dma_iommu_free_coherent,
@@ -121,6 +116,5 @@ struct dma_map_ops dma_iommu_ops = {
 	.map_page		= dma_iommu_map_page,
 	.unmap_page		= dma_iommu_unmap_page,
 	.get_required_mask	= dma_iommu_get_required_mask,
-	.mapping_error		= dma_iommu_mapping_error,
 };
 EXPORT_SYMBOL(dma_iommu_ops);
diff --git a/arch/powerpc/kernel/dma-swiotlb.c b/arch/powerpc/kernel/dma-swiotlb.c
index 5fc335f4d9cd..3d8df2cf8be9 100644
--- a/arch/powerpc/kernel/dma-swiotlb.c
+++ b/arch/powerpc/kernel/dma-swiotlb.c
@@ -59,7 +59,6 @@ const struct dma_map_ops powerpc_swiotlb_dma_ops = {
 	.sync_single_for_device = swiotlb_sync_single_for_device,
 	.sync_sg_for_cpu = swiotlb_sync_sg_for_cpu,
 	.sync_sg_for_device = swiotlb_sync_sg_for_device,
-	.mapping_error = dma_direct_mapping_error,
 	.get_required_mask = swiotlb_powerpc_get_required,
 };
 
diff --git a/arch/powerpc/kernel/iommu.c b/arch/powerpc/kernel/iommu.c
index f0dc680e659a..ca7f73488c62 100644
--- a/arch/powerpc/kernel/iommu.c
+++ b/arch/powerpc/kernel/iommu.c
@@ -197,11 +197,11 @@ static unsigned long iommu_range_alloc(struct device *dev,
 	if (unlikely(npages == 0)) {
 		if (printk_ratelimit())
 			WARN_ON(1);
-		return IOMMU_MAPPING_ERROR;
+		return DMA_MAPPING_ERROR;
 	}
 
 	if (should_fail_iommu(dev))
-		return IOMMU_MAPPING_ERROR;
+		return DMA_MAPPING_ERROR;
 
 	/*
 	 * We don't need to disable preemption here because any CPU can
@@ -277,7 +277,7 @@ static unsigned long iommu_range_alloc(struct device *dev,
 		} else {
 			/* Give up */
 			spin_unlock_irqrestore(&(pool->lock), flags);
-			return IOMMU_MAPPING_ERROR;
+			return DMA_MAPPING_ERROR;
 		}
 	}
 
@@ -309,13 +309,13 @@ static dma_addr_t iommu_alloc(struct device *dev, struct iommu_table *tbl,
 			      unsigned long attrs)
 {
 	unsigned long entry;
-	dma_addr_t ret = IOMMU_MAPPING_ERROR;
+	dma_addr_t ret = DMA_MAPPING_ERROR;
 	int build_fail;
 
 	entry = iommu_range_alloc(dev, tbl, npages, NULL, mask, align_order);
 
-	if (unlikely(entry == IOMMU_MAPPING_ERROR))
-		return IOMMU_MAPPING_ERROR;
+	if (unlikely(entry == DMA_MAPPING_ERROR))
+		return DMA_MAPPING_ERROR;
 
 	entry += tbl->it_offset;	/* Offset into real TCE table */
 	ret = entry << tbl->it_page_shift;	/* Set the return dma address */
@@ -327,12 +327,12 @@ static dma_addr_t iommu_alloc(struct device *dev, struct iommu_table *tbl,
 
 	/* tbl->it_ops->set() only returns non-zero for transient errors.
 	 * Clean up the table bitmap in this case and return
-	 * IOMMU_MAPPING_ERROR. For all other errors the functionality is
+	 * DMA_MAPPING_ERROR. For all other errors the functionality is
 	 * not altered.
 	 */
 	if (unlikely(build_fail)) {
 		__iommu_free(tbl, ret, npages);
-		return IOMMU_MAPPING_ERROR;
+		return DMA_MAPPING_ERROR;
 	}
 
 	/* Flush/invalidate TLB caches if necessary */
@@ -477,7 +477,7 @@ int ppc_iommu_map_sg(struct device *dev, struct iommu_table *tbl,
 		DBG("  - vaddr: %lx, size: %lx\n", vaddr, slen);
 
 		/* Handle failure */
-		if (unlikely(entry == IOMMU_MAPPING_ERROR)) {
+		if (unlikely(entry == DMA_MAPPING_ERROR)) {
 			if (!(attrs & DMA_ATTR_NO_WARN) &&
 			    printk_ratelimit())
 				dev_info(dev, "iommu_alloc failed, tbl %p "
@@ -544,7 +544,7 @@ int ppc_iommu_map_sg(struct device *dev, struct iommu_table *tbl,
 	 */
 	if (outcount < incount) {
 		outs = sg_next(outs);
-		outs->dma_address = IOMMU_MAPPING_ERROR;
+		outs->dma_address = DMA_MAPPING_ERROR;
 		outs->dma_length = 0;
 	}
 
@@ -562,7 +562,7 @@ int ppc_iommu_map_sg(struct device *dev, struct iommu_table *tbl,
 			npages = iommu_num_pages(s->dma_address, s->dma_length,
 						 IOMMU_PAGE_SIZE(tbl));
 			__iommu_free(tbl, vaddr, npages);
-			s->dma_address = IOMMU_MAPPING_ERROR;
+			s->dma_address = DMA_MAPPING_ERROR;
 			s->dma_length = 0;
 		}
 		if (s == outs)
@@ -776,7 +776,7 @@ dma_addr_t iommu_map_page(struct device *dev, struct iommu_table *tbl,
 			  unsigned long mask, enum dma_data_direction direction,
 			  unsigned long attrs)
 {
-	dma_addr_t dma_handle = IOMMU_MAPPING_ERROR;
+	dma_addr_t dma_handle = DMA_MAPPING_ERROR;
 	void *vaddr;
 	unsigned long uaddr;
 	unsigned int npages, align;
@@ -796,7 +796,7 @@ dma_addr_t iommu_map_page(struct device *dev, struct iommu_table *tbl,
 		dma_handle = iommu_alloc(dev, tbl, vaddr, npages, direction,
 					 mask >> tbl->it_page_shift, align,
 					 attrs);
-		if (dma_handle == IOMMU_MAPPING_ERROR) {
+		if (dma_handle == DMA_MAPPING_ERROR) {
 			if (!(attrs & DMA_ATTR_NO_WARN) &&
 			    printk_ratelimit())  {
 				dev_info(dev, "iommu_alloc failed, tbl %p "
@@ -868,7 +868,7 @@ void *iommu_alloc_coherent(struct device *dev, struct iommu_table *tbl,
 	io_order = get_iommu_order(size, tbl);
 	mapping = iommu_alloc(dev, tbl, ret, nio_pages, DMA_BIDIRECTIONAL,
 			      mask >> tbl->it_page_shift, io_order, 0);
-	if (mapping == IOMMU_MAPPING_ERROR) {
+	if (mapping == DMA_MAPPING_ERROR) {
 		free_pages((unsigned long)ret, order);
 		return NULL;
 	}
diff --git a/arch/powerpc/platforms/cell/iommu.c b/arch/powerpc/platforms/cell/iommu.c
index 12352a58072a..af2a3c15e0ec 100644
--- a/arch/powerpc/platforms/cell/iommu.c
+++ b/arch/powerpc/platforms/cell/iommu.c
@@ -654,7 +654,6 @@ static const struct dma_map_ops dma_iommu_fixed_ops = {
 	.dma_supported  = dma_suported_and_switch,
 	.map_page       = dma_fixed_map_page,
 	.unmap_page     = dma_fixed_unmap_page,
-	.mapping_error	= dma_iommu_mapping_error,
 };
 
 static void cell_dma_dev_setup(struct device *dev)
diff --git a/arch/powerpc/platforms/pseries/vio.c b/arch/powerpc/platforms/pseries/vio.c
index 88f1ad1d6309..a29ad7db918a 100644
--- a/arch/powerpc/platforms/pseries/vio.c
+++ b/arch/powerpc/platforms/pseries/vio.c
@@ -519,7 +519,7 @@ static dma_addr_t vio_dma_iommu_map_page(struct device *dev, struct page *page,
 {
 	struct vio_dev *viodev = to_vio_dev(dev);
 	struct iommu_table *tbl;
-	dma_addr_t ret = IOMMU_MAPPING_ERROR;
+	dma_addr_t ret = DMA_MAPPING_ERROR;
 
 	tbl = get_iommu_table_base(dev);
 	if (vio_cmo_alloc(viodev, roundup(size, IOMMU_PAGE_SIZE(tbl)))) {
@@ -625,7 +625,6 @@ static const struct dma_map_ops vio_dma_mapping_ops = {
 	.unmap_page        = vio_dma_iommu_unmap_page,
 	.dma_supported     = vio_dma_iommu_dma_supported,
 	.get_required_mask = vio_dma_get_required_mask,
-	.mapping_error	   = dma_iommu_mapping_error,
 };
 
 /**
diff --git a/arch/s390/pci/pci_dma.c b/arch/s390/pci/pci_dma.c
index d387a0fbdd7e..346ba382193a 100644
--- a/arch/s390/pci/pci_dma.c
+++ b/arch/s390/pci/pci_dma.c
@@ -15,8 +15,6 @@
 #include <linux/pci.h>
 #include <asm/pci_dma.h>
 
-#define S390_MAPPING_ERROR		(~(dma_addr_t) 0x0)
-
 static struct kmem_cache *dma_region_table_cache;
 static struct kmem_cache *dma_page_table_cache;
 static int s390_iommu_strict;
@@ -301,7 +299,7 @@ static dma_addr_t dma_alloc_address(struct device *dev, int size)
 
 out_error:
 	spin_unlock_irqrestore(&zdev->iommu_bitmap_lock, flags);
-	return S390_MAPPING_ERROR;
+	return DMA_MAPPING_ERROR;
 }
 
 static void dma_free_address(struct device *dev, dma_addr_t dma_addr, int size)
@@ -349,7 +347,7 @@ static dma_addr_t s390_dma_map_pages(struct device *dev, struct page *page,
 	/* This rounds up number of pages based on size and offset */
 	nr_pages = iommu_num_pages(pa, size, PAGE_SIZE);
 	dma_addr = dma_alloc_address(dev, nr_pages);
-	if (dma_addr == S390_MAPPING_ERROR) {
+	if (dma_addr == DMA_MAPPING_ERROR) {
 		ret = -ENOSPC;
 		goto out_err;
 	}
@@ -372,7 +370,7 @@ static dma_addr_t s390_dma_map_pages(struct device *dev, struct page *page,
 out_err:
 	zpci_err("map error:\n");
 	zpci_err_dma(ret, pa);
-	return S390_MAPPING_ERROR;
+	return DMA_MAPPING_ERROR;
 }
 
 static void s390_dma_unmap_pages(struct device *dev, dma_addr_t dma_addr,
@@ -449,7 +447,7 @@ static int __s390_dma_map_sg(struct device *dev, struct scatterlist *sg,
 	int ret;
 
 	dma_addr_base = dma_alloc_address(dev, nr_pages);
-	if (dma_addr_base == S390_MAPPING_ERROR)
+	if (dma_addr_base == DMA_MAPPING_ERROR)
 		return -ENOMEM;
 
 	dma_addr = dma_addr_base;
@@ -496,7 +494,7 @@ static int s390_dma_map_sg(struct device *dev, struct scatterlist *sg,
 	for (i = 1; i < nr_elements; i++) {
 		s = sg_next(s);
 
-		s->dma_address = S390_MAPPING_ERROR;
+		s->dma_address = DMA_MAPPING_ERROR;
 		s->dma_length = 0;
 
 		if (s->offset || (size & ~PAGE_MASK) ||
@@ -546,11 +544,6 @@ static void s390_dma_unmap_sg(struct device *dev, struct scatterlist *sg,
 	}
 }
 	
-static int s390_mapping_error(struct device *dev, dma_addr_t dma_addr)
-{
-	return dma_addr == S390_MAPPING_ERROR;
-}
-
 int zpci_dma_init_device(struct zpci_dev *zdev)
 {
 	int rc;
@@ -675,7 +668,6 @@ const struct dma_map_ops s390_pci_dma_ops = {
 	.unmap_sg	= s390_dma_unmap_sg,
 	.map_page	= s390_dma_map_pages,
 	.unmap_page	= s390_dma_unmap_pages,
-	.mapping_error	= s390_mapping_error,
 	/* dma_supported is unconditionally true without a callback */
 };
 EXPORT_SYMBOL_GPL(s390_pci_dma_ops);
diff --git a/arch/sparc/kernel/iommu.c b/arch/sparc/kernel/iommu.c
index 40d008b0bd3e..0626bae5e3da 100644
--- a/arch/sparc/kernel/iommu.c
+++ b/arch/sparc/kernel/iommu.c
@@ -315,7 +315,7 @@ static dma_addr_t dma_4u_map_page(struct device *dev, struct page *page,
 bad_no_ctx:
 	if (printk_ratelimit())
 		WARN_ON(1);
-	return SPARC_MAPPING_ERROR;
+	return DMA_MAPPING_ERROR;
 }
 
 static void strbuf_flush(struct strbuf *strbuf, struct iommu *iommu,
@@ -548,7 +548,7 @@ static int dma_4u_map_sg(struct device *dev, struct scatterlist *sglist,
 
 	if (outcount < incount) {
 		outs = sg_next(outs);
-		outs->dma_address = SPARC_MAPPING_ERROR;
+		outs->dma_address = DMA_MAPPING_ERROR;
 		outs->dma_length = 0;
 	}
 
@@ -574,7 +574,7 @@ static int dma_4u_map_sg(struct device *dev, struct scatterlist *sglist,
 			iommu_tbl_range_free(&iommu->tbl, vaddr, npages,
 					     IOMMU_ERROR_CODE);
 
-			s->dma_address = SPARC_MAPPING_ERROR;
+			s->dma_address = DMA_MAPPING_ERROR;
 			s->dma_length = 0;
 		}
 		if (s == outs)
@@ -742,11 +742,6 @@ static void dma_4u_sync_sg_for_cpu(struct device *dev,
 	spin_unlock_irqrestore(&iommu->lock, flags);
 }
 
-static int dma_4u_mapping_error(struct device *dev, dma_addr_t dma_addr)
-{
-	return dma_addr == SPARC_MAPPING_ERROR;
-}
-
 static int dma_4u_supported(struct device *dev, u64 device_mask)
 {
 	struct iommu *iommu = dev->archdata.iommu;
@@ -772,7 +767,6 @@ static const struct dma_map_ops sun4u_dma_ops = {
 	.sync_single_for_cpu	= dma_4u_sync_single_for_cpu,
 	.sync_sg_for_cpu	= dma_4u_sync_sg_for_cpu,
 	.dma_supported		= dma_4u_supported,
-	.mapping_error		= dma_4u_mapping_error,
 };
 
 const struct dma_map_ops *dma_ops = &sun4u_dma_ops;
diff --git a/arch/sparc/kernel/iommu_common.h b/arch/sparc/kernel/iommu_common.h
index e3c02ba32500..d62ed9c5682d 100644
--- a/arch/sparc/kernel/iommu_common.h
+++ b/arch/sparc/kernel/iommu_common.h
@@ -48,6 +48,4 @@ static inline int is_span_boundary(unsigned long entry,
 	return iommu_is_span_boundary(entry, nr, shift, boundary_size);
 }
 
-#define SPARC_MAPPING_ERROR	(~(dma_addr_t)0x0)
-
 #endif /* _IOMMU_COMMON_H */
diff --git a/arch/sparc/kernel/pci_sun4v.c b/arch/sparc/kernel/pci_sun4v.c
index 565d9ac883d0..fa0e42b4cbfb 100644
--- a/arch/sparc/kernel/pci_sun4v.c
+++ b/arch/sparc/kernel/pci_sun4v.c
@@ -414,12 +414,12 @@ static dma_addr_t dma_4v_map_page(struct device *dev, struct page *page,
 bad:
 	if (printk_ratelimit())
 		WARN_ON(1);
-	return SPARC_MAPPING_ERROR;
+	return DMA_MAPPING_ERROR;
 
 iommu_map_fail:
 	local_irq_restore(flags);
 	iommu_tbl_range_free(tbl, bus_addr, npages, IOMMU_ERROR_CODE);
-	return SPARC_MAPPING_ERROR;
+	return DMA_MAPPING_ERROR;
 }
 
 static void dma_4v_unmap_page(struct device *dev, dma_addr_t bus_addr,
@@ -592,7 +592,7 @@ static int dma_4v_map_sg(struct device *dev, struct scatterlist *sglist,
 
 	if (outcount < incount) {
 		outs = sg_next(outs);
-		outs->dma_address = SPARC_MAPPING_ERROR;
+		outs->dma_address = DMA_MAPPING_ERROR;
 		outs->dma_length = 0;
 	}
 
@@ -609,7 +609,7 @@ static int dma_4v_map_sg(struct device *dev, struct scatterlist *sglist,
 			iommu_tbl_range_free(tbl, vaddr, npages,
 					     IOMMU_ERROR_CODE);
 			/* XXX demap? XXX */
-			s->dma_address = SPARC_MAPPING_ERROR;
+			s->dma_address = DMA_MAPPING_ERROR;
 			s->dma_length = 0;
 		}
 		if (s == outs)
@@ -688,11 +688,6 @@ static int dma_4v_supported(struct device *dev, u64 device_mask)
 	return pci64_dma_supported(to_pci_dev(dev), device_mask);
 }
 
-static int dma_4v_mapping_error(struct device *dev, dma_addr_t dma_addr)
-{
-	return dma_addr == SPARC_MAPPING_ERROR;
-}
-
 static const struct dma_map_ops sun4v_dma_ops = {
 	.alloc				= dma_4v_alloc_coherent,
 	.free				= dma_4v_free_coherent,
@@ -701,7 +696,6 @@ static const struct dma_map_ops sun4v_dma_ops = {
 	.map_sg				= dma_4v_map_sg,
 	.unmap_sg			= dma_4v_unmap_sg,
 	.dma_supported			= dma_4v_supported,
-	.mapping_error			= dma_4v_mapping_error,
 };
 
 static void pci_sun4v_scan_bus(struct pci_pbm_info *pbm, struct device *parent)
diff --git a/arch/x86/kernel/amd_gart_64.c b/arch/x86/kernel/amd_gart_64.c
index 3f9d1b4019bb..07484eb36efe 100644
--- a/arch/x86/kernel/amd_gart_64.c
+++ b/arch/x86/kernel/amd_gart_64.c
@@ -50,8 +50,6 @@ static unsigned long iommu_pages;	/* .. and in pages */
 
 static u32 *iommu_gatt_base;		/* Remapping table */
 
-static dma_addr_t bad_dma_addr;
-
 /*
  * If this is disabled the IOMMU will use an optimized flushing strategy
  * of only flushing when an mapping is reused. With it true the GART is
@@ -220,7 +218,7 @@ static dma_addr_t dma_map_area(struct device *dev, dma_addr_t phys_mem,
 	int i;
 
 	if (unlikely(phys_mem + size > GART_MAX_PHYS_ADDR))
-		return bad_dma_addr;
+		return DMA_MAPPING_ERROR;
 
 	iommu_page = alloc_iommu(dev, npages, align_mask);
 	if (iommu_page == -1) {
@@ -229,7 +227,7 @@ static dma_addr_t dma_map_area(struct device *dev, dma_addr_t phys_mem,
 		if (panic_on_overflow)
 			panic("dma_map_area overflow %lu bytes\n", size);
 		iommu_full(dev, size, dir);
-		return bad_dma_addr;
+		return DMA_MAPPING_ERROR;
 	}
 
 	for (i = 0; i < npages; i++) {
@@ -315,7 +313,7 @@ static int dma_map_sg_nonforce(struct device *dev, struct scatterlist *sg,
 
 		if (nonforced_iommu(dev, addr, s->length)) {
 			addr = dma_map_area(dev, addr, s->length, dir, 0);
-			if (addr == bad_dma_addr) {
+			if (addr == DMA_MAPPING_ERROR) {
 				if (i > 0)
 					gart_unmap_sg(dev, sg, i, dir, 0);
 				nents = 0;
@@ -471,7 +469,7 @@ static int gart_map_sg(struct device *dev, struct scatterlist *sg, int nents,
 
 	iommu_full(dev, pages << PAGE_SHIFT, dir);
 	for_each_sg(sg, s, nents, i)
-		s->dma_address = bad_dma_addr;
+		s->dma_address = DMA_MAPPING_ERROR;
 	return 0;
 }
 
@@ -490,7 +488,7 @@ gart_alloc_coherent(struct device *dev, size_t size, dma_addr_t *dma_addr,
 	*dma_addr = dma_map_area(dev, virt_to_phys(vaddr), size,
 			DMA_BIDIRECTIONAL, (1UL << get_order(size)) - 1);
 	flush_gart();
-	if (unlikely(*dma_addr == bad_dma_addr))
+	if (unlikely(*dma_addr == DMA_MAPPING_ERROR))
 		goto out_free;
 	return vaddr;
 out_free:
@@ -507,11 +505,6 @@ gart_free_coherent(struct device *dev, size_t size, void *vaddr,
 	dma_direct_free_pages(dev, size, vaddr, dma_addr, attrs);
 }
 
-static int gart_mapping_error(struct device *dev, dma_addr_t dma_addr)
-{
-	return (dma_addr == bad_dma_addr);
-}
-
 static int no_agp;
 
 static __init unsigned long check_iommu_size(unsigned long aper, u64 aper_size)
@@ -695,7 +688,6 @@ static const struct dma_map_ops gart_dma_ops = {
 	.unmap_page			= gart_unmap_page,
 	.alloc				= gart_alloc_coherent,
 	.free				= gart_free_coherent,
-	.mapping_error			= gart_mapping_error,
 	.dma_supported			= dma_direct_supported,
 };
 
@@ -796,7 +788,6 @@ int __init gart_iommu_init(void)
 	agp_memory_reserved	= iommu_size;
 	iommu_start		= aper_size - iommu_size;
 	iommu_bus_base		= info.aper_base + iommu_start;
-	bad_dma_addr		= iommu_bus_base;
 	iommu_gatt_base		= agp_gatt_table + (iommu_start>>PAGE_SHIFT);
 
 	/*
diff --git a/arch/x86/kernel/pci-calgary_64.c b/arch/x86/kernel/pci-calgary_64.c
index bbfc8b1e9104..a1af5a707bb7 100644
--- a/arch/x86/kernel/pci-calgary_64.c
+++ b/arch/x86/kernel/pci-calgary_64.c
@@ -51,8 +51,6 @@
 #include <asm/x86_init.h>
 #include <asm/iommu_table.h>
 
-#define CALGARY_MAPPING_ERROR	0
-
 #ifdef CONFIG_CALGARY_IOMMU_ENABLED_BY_DEFAULT
 int use_calgary __read_mostly = 1;
 #else
@@ -255,7 +253,7 @@ static unsigned long iommu_range_alloc(struct device *dev,
 			if (panic_on_overflow)
 				panic("Calgary: fix the allocator.\n");
 			else
-				return CALGARY_MAPPING_ERROR;
+				return DMA_MAPPING_ERROR;
 		}
 	}
 
@@ -275,10 +273,10 @@ static dma_addr_t iommu_alloc(struct device *dev, struct iommu_table *tbl,
 
 	entry = iommu_range_alloc(dev, tbl, npages);
 
-	if (unlikely(entry == CALGARY_MAPPING_ERROR)) {
+	if (unlikely(entry == DMA_MAPPING_ERROR)) {
 		pr_warn("failed to allocate %u pages in iommu %p\n",
 			npages, tbl);
-		return CALGARY_MAPPING_ERROR;
+		return DMA_MAPPING_ERROR;
 	}
 
 	/* set the return dma address */
@@ -298,7 +296,7 @@ static void iommu_free(struct iommu_table *tbl, dma_addr_t dma_addr,
 	unsigned long flags;
 
 	/* were we called with bad_dma_address? */
-	badend = CALGARY_MAPPING_ERROR + (EMERGENCY_PAGES * PAGE_SIZE);
+	badend = DMA_MAPPING_ERROR + (EMERGENCY_PAGES * PAGE_SIZE);
 	if (unlikely(dma_addr < badend)) {
 		WARN(1, KERN_ERR "Calgary: driver tried unmapping bad DMA "
 		       "address 0x%Lx\n", dma_addr);
@@ -383,7 +381,7 @@ static int calgary_map_sg(struct device *dev, struct scatterlist *sg,
 		npages = iommu_num_pages(vaddr, s->length, PAGE_SIZE);
 
 		entry = iommu_range_alloc(dev, tbl, npages);
-		if (entry == CALGARY_MAPPING_ERROR) {
+		if (entry == DMA_MAPPING_ERROR) {
 			/* makes sure unmap knows to stop */
 			s->dma_length = 0;
 			goto error;
@@ -401,7 +399,7 @@ static int calgary_map_sg(struct device *dev, struct scatterlist *sg,
 error:
 	calgary_unmap_sg(dev, sg, nelems, dir, 0);
 	for_each_sg(sg, s, nelems, i) {
-		sg->dma_address = CALGARY_MAPPING_ERROR;
+		sg->dma_address = DMA_MAPPING_ERROR;
 		sg->dma_length = 0;
 	}
 	return 0;
@@ -454,7 +452,7 @@ static void* calgary_alloc_coherent(struct device *dev, size_t size,
 
 	/* set up tces to cover the allocated range */
 	mapping = iommu_alloc(dev, tbl, ret, npages, DMA_BIDIRECTIONAL);
-	if (mapping == CALGARY_MAPPING_ERROR)
+	if (mapping == DMA_MAPPING_ERROR)
 		goto free;
 	*dma_handle = mapping;
 	return ret;
@@ -479,11 +477,6 @@ static void calgary_free_coherent(struct device *dev, size_t size,
 	free_pages((unsigned long)vaddr, get_order(size));
 }
 
-static int calgary_mapping_error(struct device *dev, dma_addr_t dma_addr)
-{
-	return dma_addr == CALGARY_MAPPING_ERROR;
-}
-
 static const struct dma_map_ops calgary_dma_ops = {
 	.alloc = calgary_alloc_coherent,
 	.free = calgary_free_coherent,
@@ -491,7 +484,6 @@ static const struct dma_map_ops calgary_dma_ops = {
 	.unmap_sg = calgary_unmap_sg,
 	.map_page = calgary_map_page,
 	.unmap_page = calgary_unmap_page,
-	.mapping_error = calgary_mapping_error,
 	.dma_supported = dma_direct_supported,
 };
 
@@ -740,7 +732,7 @@ static void __init calgary_reserve_regions(struct pci_dev *dev)
 	struct iommu_table *tbl = pci_iommu(dev->bus);
 
 	/* reserve EMERGENCY_PAGES from bad_dma_address and up */
-	iommu_range_reserve(tbl, CALGARY_MAPPING_ERROR, EMERGENCY_PAGES);
+	iommu_range_reserve(tbl, DMA_MAPPING_ERROR, EMERGENCY_PAGES);
 
 	/* avoid the BIOS/VGA first 640KB-1MB region */
 	/* for CalIOC2 - avoid the entire first MB */
diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c
index 1167ff0416cf..cfb422e17049 100644
--- a/drivers/iommu/amd_iommu.c
+++ b/drivers/iommu/amd_iommu.c
@@ -55,8 +55,6 @@
 #include "amd_iommu_types.h"
 #include "irq_remapping.h"
 
-#define AMD_IOMMU_MAPPING_ERROR	0
-
 #define CMD_SET_TYPE(cmd, t) ((cmd)->data[1] |= ((t) << 28))
 
 #define LOOP_TIMEOUT	100000
@@ -2339,7 +2337,7 @@ static dma_addr_t __map_single(struct device *dev,
 	paddr &= PAGE_MASK;
 
 	address = dma_ops_alloc_iova(dev, dma_dom, pages, dma_mask);
-	if (address == AMD_IOMMU_MAPPING_ERROR)
+	if (address == DMA_MAPPING_ERROR)
 		goto out;
 
 	prot = dir2prot(direction);
@@ -2376,7 +2374,7 @@ static dma_addr_t __map_single(struct device *dev,
 
 	dma_ops_free_iova(dma_dom, address, pages);
 
-	return AMD_IOMMU_MAPPING_ERROR;
+	return DMA_MAPPING_ERROR;
 }
 
 /*
@@ -2427,7 +2425,7 @@ static dma_addr_t map_page(struct device *dev, struct page *page,
 	if (PTR_ERR(domain) == -EINVAL)
 		return (dma_addr_t)paddr;
 	else if (IS_ERR(domain))
-		return AMD_IOMMU_MAPPING_ERROR;
+		return DMA_MAPPING_ERROR;
 
 	dma_mask = *dev->dma_mask;
 	dma_dom = to_dma_ops_domain(domain);
@@ -2504,7 +2502,7 @@ static int map_sg(struct device *dev, struct scatterlist *sglist,
 	npages = sg_num_pages(dev, sglist, nelems);
 
 	address = dma_ops_alloc_iova(dev, dma_dom, npages, dma_mask);
-	if (address == AMD_IOMMU_MAPPING_ERROR)
+	if (address == DMA_MAPPING_ERROR)
 		goto out_err;
 
 	prot = dir2prot(direction);
@@ -2627,7 +2625,7 @@ static void *alloc_coherent(struct device *dev, size_t size,
 	*dma_addr = __map_single(dev, dma_dom, page_to_phys(page),
 				 size, DMA_BIDIRECTIONAL, dma_mask);
 
-	if (*dma_addr == AMD_IOMMU_MAPPING_ERROR)
+	if (*dma_addr == DMA_MAPPING_ERROR)
 		goto out_free;
 
 	return page_address(page);
@@ -2678,11 +2676,6 @@ static int amd_iommu_dma_supported(struct device *dev, u64 mask)
 	return check_device(dev);
 }
 
-static int amd_iommu_mapping_error(struct device *dev, dma_addr_t dma_addr)
-{
-	return dma_addr == AMD_IOMMU_MAPPING_ERROR;
-}
-
 static const struct dma_map_ops amd_iommu_dma_ops = {
 	.alloc		= alloc_coherent,
 	.free		= free_coherent,
@@ -2691,7 +2684,6 @@ static const struct dma_map_ops amd_iommu_dma_ops = {
 	.map_sg		= map_sg,
 	.unmap_sg	= unmap_sg,
 	.dma_supported	= amd_iommu_dma_supported,
-	.mapping_error	= amd_iommu_mapping_error,
 };
 
 static int init_reserved_iova_ranges(void)
diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index d1b04753b204..60c7e9e9901e 100644
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c
@@ -32,8 +32,6 @@
 #include <linux/scatterlist.h>
 #include <linux/vmalloc.h>
 
-#define IOMMU_MAPPING_ERROR	0
-
 struct iommu_dma_msi_page {
 	struct list_head	list;
 	dma_addr_t		iova;
@@ -523,7 +521,7 @@ void iommu_dma_free(struct device *dev, struct page **pages, size_t size,
 {
 	__iommu_dma_unmap(iommu_get_dma_domain(dev), *handle, size);
 	__iommu_dma_free_pages(pages, PAGE_ALIGN(size) >> PAGE_SHIFT);
-	*handle = IOMMU_MAPPING_ERROR;
+	*handle = DMA_MAPPING_ERROR;
 }
 
 /**
@@ -556,7 +554,7 @@ struct page **iommu_dma_alloc(struct device *dev, size_t size, gfp_t gfp,
 	dma_addr_t iova;
 	unsigned int count, min_size, alloc_sizes = domain->pgsize_bitmap;
 
-	*handle = IOMMU_MAPPING_ERROR;
+	*handle = DMA_MAPPING_ERROR;
 
 	min_size = alloc_sizes & -alloc_sizes;
 	if (min_size < PAGE_SIZE) {
@@ -649,11 +647,11 @@ static dma_addr_t __iommu_dma_map(struct device *dev, phys_addr_t phys,
 
 	iova = iommu_dma_alloc_iova(domain, size, dma_get_mask(dev), dev);
 	if (!iova)
-		return IOMMU_MAPPING_ERROR;
+		return DMA_MAPPING_ERROR;
 
 	if (iommu_map(domain, iova, phys - iova_off, size, prot)) {
 		iommu_dma_free_iova(cookie, iova, size);
-		return IOMMU_MAPPING_ERROR;
+		return DMA_MAPPING_ERROR;
 	}
 	return iova + iova_off;
 }
@@ -694,7 +692,7 @@ static int __finalise_sg(struct device *dev, struct scatterlist *sg, int nents,
 
 		s->offset += s_iova_off;
 		s->length = s_length;
-		sg_dma_address(s) = IOMMU_MAPPING_ERROR;
+		sg_dma_address(s) = DMA_MAPPING_ERROR;
 		sg_dma_len(s) = 0;
 
 		/*
@@ -737,11 +735,11 @@ static void __invalidate_sg(struct scatterlist *sg, int nents)
 	int i;
 
 	for_each_sg(sg, s, nents, i) {
-		if (sg_dma_address(s) != IOMMU_MAPPING_ERROR)
+		if (sg_dma_address(s) != DMA_MAPPING_ERROR)
 			s->offset += sg_dma_address(s);
 		if (sg_dma_len(s))
 			s->length = sg_dma_len(s);
-		sg_dma_address(s) = IOMMU_MAPPING_ERROR;
+		sg_dma_address(s) = DMA_MAPPING_ERROR;
 		sg_dma_len(s) = 0;
 	}
 }
@@ -858,11 +856,6 @@ void iommu_dma_unmap_resource(struct device *dev, dma_addr_t handle,
 	__iommu_dma_unmap(iommu_get_dma_domain(dev), handle, size);
 }
 
-int iommu_dma_mapping_error(struct device *dev, dma_addr_t dma_addr)
-{
-	return dma_addr == IOMMU_MAPPING_ERROR;
-}
-
 static struct iommu_dma_msi_page *iommu_dma_get_msi_page(struct device *dev,
 		phys_addr_t msi_addr, struct iommu_domain *domain)
 {
@@ -882,7 +875,7 @@ static struct iommu_dma_msi_page *iommu_dma_get_msi_page(struct device *dev,
 		return NULL;
 
 	iova = __iommu_dma_map(dev, msi_addr, size, prot, domain);
-	if (iommu_dma_mapping_error(dev, iova))
+	if (iova == DMA_MAPPING_ERROR)
 		goto out_free_page;
 
 	INIT_LIST_HEAD(&msi_page->list);
diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index f3ccf025108b..ffc4864d0ed7 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -3661,8 +3661,13 @@ static dma_addr_t intel_map_page(struct device *dev, struct page *page,
 				 enum dma_data_direction dir,
 				 unsigned long attrs)
 {
-	return __intel_map_single(dev, page_to_phys(page) + offset, size,
+	dma_addr_t dma_addr;
+
+	dma_addr = __intel_map_single(dev, page_to_phys(page) + offset, size,
 				  dir, *dev->dma_mask);
+	if (dma_addr == 0)
+		return DMA_MAPPING_ERROR;
+	return dma_addr;
 }
 
 static void intel_unmap(struct device *dev, dma_addr_t dev_addr, size_t size)
@@ -3865,11 +3870,6 @@ static int intel_map_sg(struct device *dev, struct scatterlist *sglist, int nele
 	return nelems;
 }
 
-static int intel_mapping_error(struct device *dev, dma_addr_t dma_addr)
-{
-	return !dma_addr;
-}
-
 static const struct dma_map_ops intel_dma_ops = {
 	.alloc = intel_alloc_coherent,
 	.free = intel_free_coherent,
@@ -3877,7 +3877,6 @@ static const struct dma_map_ops intel_dma_ops = {
 	.unmap_sg = intel_unmap_sg,
 	.map_page = intel_map_page,
 	.unmap_page = intel_unmap_page,
-	.mapping_error = intel_mapping_error,
 	.dma_supported = dma_direct_supported,
 };
 
diff --git a/drivers/parisc/ccio-dma.c b/drivers/parisc/ccio-dma.c
index 701a7d6a74d5..714aac72df0e 100644
--- a/drivers/parisc/ccio-dma.c
+++ b/drivers/parisc/ccio-dma.c
@@ -110,8 +110,6 @@
 #define CMD_TLB_DIRECT_WRITE 35         /* IO_COMMAND for I/O TLB Writes     */
 #define CMD_TLB_PURGE        33         /* IO_COMMAND to Purge I/O TLB entry */
 
-#define CCIO_MAPPING_ERROR    (~(dma_addr_t)0)
-
 struct ioa_registers {
         /* Runway Supervisory Set */
         int32_t    unused1[12];
@@ -740,7 +738,7 @@ ccio_map_single(struct device *dev, void *addr, size_t size,
 	BUG_ON(!dev);
 	ioc = GET_IOC(dev);
 	if (!ioc)
-		return CCIO_MAPPING_ERROR;
+		return DMA_MAPPING_ERROR;
 
 	BUG_ON(size <= 0);
 
@@ -1021,11 +1019,6 @@ ccio_unmap_sg(struct device *dev, struct scatterlist *sglist, int nents,
 	DBG_RUN_SG("%s() DONE (nents %d)\n", __func__, nents);
 }
 
-static int ccio_mapping_error(struct device *dev, dma_addr_t dma_addr)
-{
-	return dma_addr == CCIO_MAPPING_ERROR;
-}
-
 static const struct dma_map_ops ccio_ops = {
 	.dma_supported =	ccio_dma_supported,
 	.alloc =		ccio_alloc,
@@ -1034,7 +1027,6 @@ static const struct dma_map_ops ccio_ops = {
 	.unmap_page =		ccio_unmap_page,
 	.map_sg = 		ccio_map_sg,
 	.unmap_sg = 		ccio_unmap_sg,
-	.mapping_error =	ccio_mapping_error,
 };
 
 #ifdef CONFIG_PROC_FS
diff --git a/drivers/parisc/sba_iommu.c b/drivers/parisc/sba_iommu.c
index c1e599a429af..452d306ce5cb 100644
--- a/drivers/parisc/sba_iommu.c
+++ b/drivers/parisc/sba_iommu.c
@@ -93,8 +93,6 @@
 
 #define DEFAULT_DMA_HINT_REG	0
 
-#define SBA_MAPPING_ERROR    (~(dma_addr_t)0)
-
 struct sba_device *sba_list;
 EXPORT_SYMBOL_GPL(sba_list);
 
@@ -725,7 +723,7 @@ sba_map_single(struct device *dev, void *addr, size_t size,
 
 	ioc = GET_IOC(dev);
 	if (!ioc)
-		return SBA_MAPPING_ERROR;
+		return DMA_MAPPING_ERROR;
 
 	/* save offset bits */
 	offset = ((dma_addr_t) (long) addr) & ~IOVP_MASK;
@@ -1080,11 +1078,6 @@ sba_unmap_sg(struct device *dev, struct scatterlist *sglist, int nents,
 
 }
 
-static int sba_mapping_error(struct device *dev, dma_addr_t dma_addr)
-{
-	return dma_addr == SBA_MAPPING_ERROR;
-}
-
 static const struct dma_map_ops sba_ops = {
 	.dma_supported =	sba_dma_supported,
 	.alloc =		sba_alloc,
@@ -1093,7 +1086,6 @@ static const struct dma_map_ops sba_ops = {
 	.unmap_page =		sba_unmap_page,
 	.map_sg =		sba_map_sg,
 	.unmap_sg =		sba_unmap_sg,
-	.mapping_error =	sba_mapping_error,
 };
 
 
diff --git a/drivers/pci/controller/vmd.c b/drivers/pci/controller/vmd.c
index e50b0b5815ff..98ce79eac128 100644
--- a/drivers/pci/controller/vmd.c
+++ b/drivers/pci/controller/vmd.c
@@ -394,11 +394,6 @@ static void vmd_sync_sg_for_device(struct device *dev, struct scatterlist *sg,
 	vmd_dma_ops(dev)->sync_sg_for_device(to_vmd_dev(dev), sg, nents, dir);
 }
 
-static int vmd_mapping_error(struct device *dev, dma_addr_t addr)
-{
-	return vmd_dma_ops(dev)->mapping_error(to_vmd_dev(dev), addr);
-}
-
 static int vmd_dma_supported(struct device *dev, u64 mask)
 {
 	return vmd_dma_ops(dev)->dma_supported(to_vmd_dev(dev), mask);
@@ -446,7 +441,6 @@ static void vmd_setup_dma_ops(struct vmd_dev *vmd)
 	ASSIGN_VMD_DMA_OPS(source, dest, sync_single_for_device);
 	ASSIGN_VMD_DMA_OPS(source, dest, sync_sg_for_cpu);
 	ASSIGN_VMD_DMA_OPS(source, dest, sync_sg_for_device);
-	ASSIGN_VMD_DMA_OPS(source, dest, mapping_error);
 	ASSIGN_VMD_DMA_OPS(source, dest, dma_supported);
 	ASSIGN_VMD_DMA_OPS(source, dest, get_required_mask);
 	add_dma_domain(domain);
diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
index 2a7f545bd0b5..6dc969d5ea2f 100644
--- a/drivers/xen/swiotlb-xen.c
+++ b/drivers/xen/swiotlb-xen.c
@@ -53,8 +53,6 @@
  * API.
  */
 
-#define XEN_SWIOTLB_ERROR_CODE	(~(dma_addr_t)0x0)
-
 static char *xen_io_tlb_start, *xen_io_tlb_end;
 static unsigned long xen_io_tlb_nslabs;
 /*
@@ -406,7 +404,7 @@ static dma_addr_t xen_swiotlb_map_page(struct device *dev, struct page *page,
 	map = swiotlb_tbl_map_single(dev, start_dma_addr, phys, size, dir,
 				     attrs);
 	if (map == SWIOTLB_MAP_ERROR)
-		return XEN_SWIOTLB_ERROR_CODE;
+		return DMA_MAPPING_ERROR;
 
 	dev_addr = xen_phys_to_bus(map);
 	xen_dma_map_page(dev, pfn_to_page(map >> PAGE_SHIFT),
@@ -421,7 +419,7 @@ static dma_addr_t xen_swiotlb_map_page(struct device *dev, struct page *page,
 	attrs |= DMA_ATTR_SKIP_CPU_SYNC;
 	swiotlb_tbl_unmap_single(dev, map, size, dir, attrs);
 
-	return XEN_SWIOTLB_ERROR_CODE;
+	return DMA_MAPPING_ERROR;
 }
 
 /*
@@ -700,11 +698,6 @@ xen_swiotlb_get_sgtable(struct device *dev, struct sg_table *sgt,
 	return dma_common_get_sgtable(dev, sgt, cpu_addr, handle, size, attrs);
 }
 
-static int xen_swiotlb_mapping_error(struct device *dev, dma_addr_t dma_addr)
-{
-	return dma_addr == XEN_SWIOTLB_ERROR_CODE;
-}
-
 const struct dma_map_ops xen_swiotlb_dma_ops = {
 	.alloc = xen_swiotlb_alloc_coherent,
 	.free = xen_swiotlb_free_coherent,
@@ -719,5 +712,4 @@ const struct dma_map_ops xen_swiotlb_dma_ops = {
 	.dma_supported = xen_swiotlb_dma_supported,
 	.mmap = xen_swiotlb_dma_mmap,
 	.get_sgtable = xen_swiotlb_get_sgtable,
-	.mapping_error	= xen_swiotlb_mapping_error,
 };
diff --git a/include/linux/dma-direct.h b/include/linux/dma-direct.h
index bd73e7a91410..e7600f92d876 100644
--- a/include/linux/dma-direct.h
+++ b/include/linux/dma-direct.h
@@ -5,8 +5,6 @@
 #include <linux/dma-mapping.h>
 #include <linux/mem_encrypt.h>
 
-#define DIRECT_MAPPING_ERROR		0
-
 #ifdef CONFIG_ARCH_HAS_PHYS_TO_DMA
 #include <asm/dma-direct.h>
 #else
@@ -73,5 +71,4 @@ dma_addr_t dma_direct_map_page(struct device *dev, struct page *page,
 int dma_direct_map_sg(struct device *dev, struct scatterlist *sgl, int nents,
 		enum dma_data_direction dir, unsigned long attrs);
 int dma_direct_supported(struct device *dev, u64 mask);
-int dma_direct_mapping_error(struct device *dev, dma_addr_t dma_addr);
 #endif /* _LINUX_DMA_DIRECT_H */
diff --git a/include/linux/dma-iommu.h b/include/linux/dma-iommu.h
index e8ca5e654277..e760dc5d1fa8 100644
--- a/include/linux/dma-iommu.h
+++ b/include/linux/dma-iommu.h
@@ -69,7 +69,6 @@ dma_addr_t iommu_dma_map_resource(struct device *dev, phys_addr_t phys,
 		size_t size, enum dma_data_direction dir, unsigned long attrs);
 void iommu_dma_unmap_resource(struct device *dev, dma_addr_t handle,
 		size_t size, enum dma_data_direction dir, unsigned long attrs);
-int iommu_dma_mapping_error(struct device *dev, dma_addr_t dma_addr);
 
 /* The DMA API isn't _quite_ the whole story, though... */
 void iommu_dma_map_msi_msg(int irq, struct msi_msg *msg);
diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
index 15bd41447025..c08779649ac0 100644
--- a/include/linux/dma-mapping.h
+++ b/include/linux/dma-mapping.h
@@ -128,11 +128,15 @@ struct dma_map_ops {
 				   enum dma_data_direction dir);
 	void (*cache_sync)(struct device *dev, void *vaddr, size_t size,
 			enum dma_data_direction direction);
-	int (*mapping_error)(struct device *dev, dma_addr_t dma_addr);
 	int (*dma_supported)(struct device *dev, u64 mask);
 	u64 (*get_required_mask)(struct device *dev);
 };
 
+/*
+ * Error return value from ->map_page.
+ */
+#define DMA_MAPPING_ERROR	(~(dma_addr_t)0x0)
+
 extern const struct dma_map_ops dma_direct_ops;
 extern const struct dma_map_ops dma_virt_ops;
 
@@ -573,12 +577,8 @@ static inline void dma_free_coherent(struct device *dev, size_t size,
 
 static inline int dma_mapping_error(struct device *dev, dma_addr_t dma_addr)
 {
-	const struct dma_map_ops *ops = get_dma_ops(dev);
-
 	debug_dma_mapping_error(dev, dma_addr);
-	if (ops->mapping_error)
-		return ops->mapping_error(dev, dma_addr);
-	return 0;
+	return dma_addr == DMA_MAPPING_ERROR;
 }
 
 static inline void dma_check_mask(struct device *dev, u64 mask)
diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c
index 22a12ab5a5e9..d4335a03193a 100644
--- a/kernel/dma/direct.c
+++ b/kernel/dma/direct.c
@@ -265,7 +265,7 @@ dma_addr_t dma_direct_map_page(struct device *dev, struct page *page,
 	dma_addr_t dma_addr = phys_to_dma(dev, phys);
 
 	if (!check_addr(dev, dma_addr, size, __func__))
-		return DIRECT_MAPPING_ERROR;
+		return DMA_MAPPING_ERROR;
 
 	if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC))
 		dma_direct_sync_single_for_device(dev, dma_addr, size, dir);
@@ -312,11 +312,6 @@ int dma_direct_supported(struct device *dev, u64 mask)
 	return mask >= phys_to_dma(dev, min_mask);
 }
 
-int dma_direct_mapping_error(struct device *dev, dma_addr_t dma_addr)
-{
-	return dma_addr == DIRECT_MAPPING_ERROR;
-}
-
 const struct dma_map_ops dma_direct_ops = {
 	.alloc			= dma_direct_alloc,
 	.free			= dma_direct_free,
@@ -335,7 +330,6 @@ const struct dma_map_ops dma_direct_ops = {
 #endif
 	.get_required_mask	= dma_direct_get_required_mask,
 	.dma_supported		= dma_direct_supported,
-	.mapping_error		= dma_direct_mapping_error,
 	.cache_sync		= arch_dma_cache_sync,
 };
 EXPORT_SYMBOL(dma_direct_ops);
diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
index 5731daa09a32..42b0c7d50d2b 100644
--- a/kernel/dma/swiotlb.c
+++ b/kernel/dma/swiotlb.c
@@ -631,21 +631,21 @@ static dma_addr_t swiotlb_bounce_page(struct device *dev, phys_addr_t *phys,
 	if (unlikely(swiotlb_force == SWIOTLB_NO_FORCE)) {
 		dev_warn_ratelimited(dev,
 			"Cannot do DMA to address %pa\n", phys);
-		return DIRECT_MAPPING_ERROR;
+		return DMA_MAPPING_ERROR;
 	}
 
 	/* Oh well, have to allocate and map a bounce buffer. */
 	*phys = swiotlb_tbl_map_single(dev, __phys_to_dma(dev, io_tlb_start),
 			*phys, size, dir, attrs);
 	if (*phys == SWIOTLB_MAP_ERROR)
-		return DIRECT_MAPPING_ERROR;
+		return DMA_MAPPING_ERROR;
 
 	/* Ensure that the address returned is DMA'ble */
 	dma_addr = __phys_to_dma(dev, *phys);
 	if (unlikely(!dma_capable(dev, dma_addr, size))) {
 		swiotlb_tbl_unmap_single(dev, *phys, size, dir,
 			attrs | DMA_ATTR_SKIP_CPU_SYNC);
-		return DIRECT_MAPPING_ERROR;
+		return DMA_MAPPING_ERROR;
 	}
 
 	return dma_addr;
@@ -788,7 +788,7 @@ swiotlb_map_sg_attrs(struct device *dev, struct scatterlist *sgl, int nelems,
 	for_each_sg(sgl, sg, nelems, i) {
 		sg->dma_address = swiotlb_map_page(dev, sg_page(sg), sg->offset,
 				sg->length, dir, attrs);
-		if (sg->dma_address == DIRECT_MAPPING_ERROR)
+		if (sg->dma_address == DMA_MAPPING_ERROR)
 			goto out_error;
 		sg_dma_len(sg) = sg->length;
 	}
@@ -868,7 +868,6 @@ swiotlb_dma_supported(struct device *hwdev, u64 mask)
 }
 
 const struct dma_map_ops swiotlb_dma_ops = {
-	.mapping_error		= dma_direct_mapping_error,
 	.alloc			= dma_direct_alloc,
 	.free			= dma_direct_free,
 	.sync_single_for_cpu	= swiotlb_sync_single_for_cpu,
-- 
2.19.1

Re: [PATCH 1/2] dma-mapping: remove ->mapping_error

[Robin Murphy]

On 09/11/2018 08:46, Christoph Hellwig wrote:
[...]
> diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c
> index 1167ff0416cf..cfb422e17049 100644
> --- a/drivers/iommu/amd_iommu.c
> +++ b/drivers/iommu/amd_iommu.c
> @@ -55,8 +55,6 @@
>   #include "amd_iommu_types.h"
>   #include "irq_remapping.h"
>   
> -#define AMD_IOMMU_MAPPING_ERROR	0
> -
>   #define CMD_SET_TYPE(cmd, t) ((cmd)->data[1] |= ((t) << 28))
>   
>   #define LOOP_TIMEOUT	100000
> @@ -2339,7 +2337,7 @@ static dma_addr_t __map_single(struct device *dev,
>   	paddr &= PAGE_MASK;
>   
>   	address = dma_ops_alloc_iova(dev, dma_dom, pages, dma_mask);
> -	if (address == AMD_IOMMU_MAPPING_ERROR)
> +	if (address == DMA_MAPPING_ERROR)

This for one is clearly broken, because the IOVA allocator still returns 
0 on failure here...

>   		goto out;
>   
>   	prot = dir2prot(direction);
> @@ -2376,7 +2374,7 @@ static dma_addr_t __map_single(struct device *dev,
>   
>   	dma_ops_free_iova(dma_dom, address, pages);
>   
> -	return AMD_IOMMU_MAPPING_ERROR;
> +	return DMA_MAPPING_ERROR;
>   }
>   
>   /*
> @@ -2427,7 +2425,7 @@ static dma_addr_t map_page(struct device *dev, struct page *page,
>   	if (PTR_ERR(domain) == -EINVAL)
>   		return (dma_addr_t)paddr;
>   	else if (IS_ERR(domain))
> -		return AMD_IOMMU_MAPPING_ERROR;
> +		return DMA_MAPPING_ERROR;
>   
>   	dma_mask = *dev->dma_mask;
>   	dma_dom = to_dma_ops_domain(domain);
> @@ -2504,7 +2502,7 @@ static int map_sg(struct device *dev, struct scatterlist *sglist,
>   	npages = sg_num_pages(dev, sglist, nelems);
>   
>   	address = dma_ops_alloc_iova(dev, dma_dom, npages, dma_mask);
> -	if (address == AMD_IOMMU_MAPPING_ERROR)
> +	if (address == DMA_MAPPING_ERROR)

..and here.

I very much agree with the concept, but I think the way to go about it 
is to convert the implementations which need it to the standardised 
*_MAPPING_ERROR value one-by-one, and only then then do the big sweep to 
remove them all. That has more of a chance of getting worthwhile review 
and testing from the respective relevant parties (I'll confess I came 
looking for this bug specifically, since I happened to recall amd_iommu 
having a tricky implicit reliance on the old DMA_ERROR_CODE being 0 on x86).

In terms of really minimising the error-checking overhead it's a bit of 
a shame that DMA_MAPPING_ERROR = 0 doesn't seem viable as the thing to 
standardise on, since that has advantages at the micro-optimisation 
level for many ISAs - fixing up the legacy IOMMU code doesn't seem 
insurmountable, but I suspect there may well be non-IOMMU platforms 
where DMA to physical address 0 is a thing :(

(yeah, I know saving a couple of instructions and potential register 
allocations is down in the noise when we're already going from an 
indirect call to an inline comparison; I'm mostly just thinking out loud 
there)

Robin.

>   		goto out_err;
>   
>   	prot = dir2prot(direction);
> @@ -2627,7 +2625,7 @@ static void *alloc_coherent(struct device *dev, size_t size,
>   	*dma_addr = __map_single(dev, dma_dom, page_to_phys(page),
>   				 size, DMA_BIDIRECTIONAL, dma_mask);
>   
> -	if (*dma_addr == AMD_IOMMU_MAPPING_ERROR)
> +	if (*dma_addr == DMA_MAPPING_ERROR)
>   		goto out_free;
>   
>   	return page_address(page);
> @@ -2678,11 +2676,6 @@ static int amd_iommu_dma_supported(struct device *dev, u64 mask)
>   	return check_device(dev);
>   }
>   
> -static int amd_iommu_mapping_error(struct device *dev, dma_addr_t dma_addr)
> -{
> -	return dma_addr == AMD_IOMMU_MAPPING_ERROR;
> -}
> -
>   static const struct dma_map_ops amd_iommu_dma_ops = {
>   	.alloc		= alloc_coherent,
>   	.free		= free_coherent,
> @@ -2691,7 +2684,6 @@ static const struct dma_map_ops amd_iommu_dma_ops = {
>   	.map_sg		= map_sg,
>   	.unmap_sg	= unmap_sg,
>   	.dma_supported	= amd_iommu_dma_supported,
> -	.mapping_error	= amd_iommu_mapping_error,
>   };
>   
>   static int init_reserved_iova_ranges(void)

Re: [PATCH 1/2] dma-mapping: remove ->mapping_error

[Christoph Hellwig]

On Fri, Nov 09, 2018 at 02:41:18PM +0000, Robin Murphy wrote:
>> -
>>   #define CMD_SET_TYPE(cmd, t) ((cmd)->data[1] |= ((t) << 28))
>>     #define LOOP_TIMEOUT	100000
>> @@ -2339,7 +2337,7 @@ static dma_addr_t __map_single(struct device *dev,
>>   	paddr &= PAGE_MASK;
>>     	address = dma_ops_alloc_iova(dev, dma_dom, pages, dma_mask);
>> -	if (address == AMD_IOMMU_MAPPING_ERROR)
>> +	if (address == DMA_MAPPING_ERROR)
>
> This for one is clearly broken, because the IOVA allocator still returns 0 
> on failure here...

Indeed.  And that shows how the original code was making a mess of these
different constants..

> I very much agree with the concept, but I think the way to go about it is 
> to convert the implementations which need it to the standardised 
> *_MAPPING_ERROR value one-by-one, and only then then do the big sweep to 
> remove them all. That has more of a chance of getting worthwhile review and 
> testing from the respective relevant parties (I'll confess I came looking 
> for this bug specifically, since I happened to recall amd_iommu having a 
> tricky implicit reliance on the old DMA_ERROR_CODE being 0 on x86).

I'll see if I can split this out somehow, but I'm not sure it is going
to be all that much more readable..

> In terms of really minimising the error-checking overhead it's a bit of a 
> shame that DMA_MAPPING_ERROR = 0 doesn't seem viable as the thing to 
> standardise on, since that has advantages at the micro-optimisation level 
> for many ISAs - fixing up the legacy IOMMU code doesn't seem 
> insurmountable, but I suspect there may well be non-IOMMU platforms where 
> DMA to physical address 0 is a thing :(

Yes, that is what I'm more worried about.

> (yeah, I know saving a couple of instructions and potential register 
> allocations is down in the noise when we're already going from an indirect 
> call to an inline comparison; I'm mostly just thinking out loud there)

The nice bit of standardizing the value is that we get rid of an
indirect call, which generally is much more of a problem at the
micro-architecture level.

[PATCH 2/2] dma-mapping: return errors from dma_map_page and dma_map_attrs

[Christoph Hellwig]

The current DMA API map_page and map_single routines use a very bad API
pattern that makes error checking hard.  The calls to them are far too
many and too complex to easily change that, but the relatively new _attr
variants that take an additional attributs argument only have a few
callers and can be changed easily.  So here we change them to return
an errno value, and return the dma address by reference to allow for
much saner error checking.

In the long run we should move existing callers of dma_map_page and
dma_map_single to these _attr variants with a 0 attrs argument to get
the better API everywhere, but without a single flag day.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 Documentation/DMA-API.txt                     |  4 +-
 drivers/crypto/caam/caamalg.c                 |  8 +--
 drivers/crypto/caam/caamalg_qi2.c             | 13 ++--
 drivers/crypto/caam/caamhash.c                |  8 +--
 drivers/crypto/talitos.c                      |  4 +-
 drivers/gpu/drm/i915/i915_gem_gtt.c           | 19 +++---
 drivers/net/ethernet/broadcom/bnxt/bnxt.c     | 20 +++---
 .../ethernet/cavium/thunder/nicvf_queues.c    | 27 ++++----
 drivers/net/ethernet/intel/i40e/i40e_txrx.c   | 11 +---
 drivers/net/ethernet/intel/i40e/i40e_xsk.c    |  5 +-
 drivers/net/ethernet/intel/iavf/iavf_txrx.c   | 11 +---
 drivers/net/ethernet/intel/igb/igb_main.c     | 11 +---
 drivers/net/ethernet/intel/igc/igc_main.c     | 11 +---
 drivers/net/ethernet/intel/ixgbe/ixgbe_main.c | 12 +---
 drivers/net/ethernet/intel/ixgbe/ixgbe_xsk.c  |  5 +-
 .../net/ethernet/intel/ixgbevf/ixgbevf_main.c | 11 +---
 .../ethernet/netronome/nfp/nfp_net_common.c   | 12 ++--
 include/linux/dma-mapping.h                   | 62 +++++++++++++------
 18 files changed, 109 insertions(+), 145 deletions(-)

diff --git a/Documentation/DMA-API.txt b/Documentation/DMA-API.txt
index ac66ae2509a9..2a9069907470 100644
--- a/Documentation/DMA-API.txt
+++ b/Documentation/DMA-API.txt
@@ -439,10 +439,10 @@ See also dma_map_single().
 
 ::
 
-	dma_addr_t
+	int	
 	dma_map_single_attrs(struct device *dev, void *cpu_addr, size_t size,
 			     enum dma_data_direction dir,
-			     unsigned long attrs)
+			     unsigned long attrs, dma_addr_t *dma_handle);
 
 	void
 	dma_unmap_single_attrs(struct device *dev, dma_addr_t dma_addr,
diff --git a/drivers/crypto/caam/caamalg.c b/drivers/crypto/caam/caamalg.c
index 869f092432de..cbcd55fda24f 100644
--- a/drivers/crypto/caam/caamalg.c
+++ b/drivers/crypto/caam/caamalg.c
@@ -3022,11 +3022,9 @@ static int caam_init_common(struct caam_ctx *ctx, struct caam_alg_entry *caam,
 	else
 		ctx->dir = DMA_TO_DEVICE;
 
-	dma_addr = dma_map_single_attrs(ctx->jrdev, ctx->sh_desc_enc,
-					offsetof(struct caam_ctx,
-						 sh_desc_enc_dma),
-					ctx->dir, DMA_ATTR_SKIP_CPU_SYNC);
-	if (dma_mapping_error(ctx->jrdev, dma_addr)) {
+	if (dma_map_single_attrs(ctx->jrdev, ctx->sh_desc_enc,
+			offsetof(struct caam_ctx, sh_desc_enc_dma),
+			ctx->dir, DMA_ATTR_SKIP_CPU_SYNC, &dma_addr)) {
 		dev_err(ctx->jrdev, "unable to map key, shared descriptors\n");
 		caam_jr_free(ctx->jrdev);
 		return -ENOMEM;
diff --git a/drivers/crypto/caam/caamalg_qi2.c b/drivers/crypto/caam/caamalg_qi2.c
index 7d8ac0222fa3..9453dca56798 100644
--- a/drivers/crypto/caam/caamalg_qi2.c
+++ b/drivers/crypto/caam/caamalg_qi2.c
@@ -1336,10 +1336,9 @@ static int caam_cra_init(struct caam_ctx *ctx, struct caam_alg_entry *caam,
 	ctx->dev = caam->dev;
 	ctx->dir = uses_dkp ? DMA_BIDIRECTIONAL : DMA_TO_DEVICE;
 
-	dma_addr = dma_map_single_attrs(ctx->dev, ctx->flc,
-					offsetof(struct caam_ctx, flc_dma),
-					ctx->dir, DMA_ATTR_SKIP_CPU_SYNC);
-	if (dma_mapping_error(ctx->dev, dma_addr)) {
+	if (dma_map_single_attrs(ctx->dev, ctx->flc,
+			offsetof(struct caam_ctx, flc_dma),
+			ctx->dir, DMA_ATTR_SKIP_CPU_SYNC, &dma_addr)) {
 		dev_err(ctx->dev, "unable to map key, shared descriptors\n");
 		return -ENOMEM;
 	}
@@ -4272,10 +4271,8 @@ static int caam_hash_cra_init(struct crypto_tfm *tfm)
 
 	ctx->dev = caam_hash->dev;
 
-	dma_addr = dma_map_single_attrs(ctx->dev, ctx->flc, sizeof(ctx->flc),
-					DMA_BIDIRECTIONAL,
-					DMA_ATTR_SKIP_CPU_SYNC);
-	if (dma_mapping_error(ctx->dev, dma_addr)) {
+	if (dma_map_single_attrs(ctx->dev, ctx->flc, sizeof(ctx->flc),
+			DMA_BIDIRECTIONAL, DMA_ATTR_SKIP_CPU_SYNC, &dma_addr)) {
 		dev_err(ctx->dev, "unable to map shared descriptors\n");
 		return -ENOMEM;
 	}
diff --git a/drivers/crypto/caam/caamhash.c b/drivers/crypto/caam/caamhash.c
index 46924affa0bd..e0bc10ab891e 100644
--- a/drivers/crypto/caam/caamhash.c
+++ b/drivers/crypto/caam/caamhash.c
@@ -1693,11 +1693,9 @@ static int caam_hash_cra_init(struct crypto_tfm *tfm)
 	priv = dev_get_drvdata(ctx->jrdev->parent);
 	ctx->dir = priv->era >= 6 ? DMA_BIDIRECTIONAL : DMA_TO_DEVICE;
 
-	dma_addr = dma_map_single_attrs(ctx->jrdev, ctx->sh_desc_update,
-					offsetof(struct caam_hash_ctx,
-						 sh_desc_update_dma),
-					ctx->dir, DMA_ATTR_SKIP_CPU_SYNC);
-	if (dma_mapping_error(ctx->jrdev, dma_addr)) {
+	if (dma_map_single_attrs(ctx->jrdev, ctx->sh_desc_update,
+			offsetof(struct caam_hash_ctx, sh_desc_update_dma),
+			ctx->dir, DMA_ATTR_SKIP_CPU_SYNC, &dma_addr)) {
 		dev_err(ctx->jrdev, "unable to map shared descriptors\n");
 		caam_jr_free(ctx->jrdev);
 		return -ENOMEM;
diff --git a/drivers/crypto/talitos.c b/drivers/crypto/talitos.c
index 6988012deca4..1b0f816994bf 100644
--- a/drivers/crypto/talitos.c
+++ b/drivers/crypto/talitos.c
@@ -110,10 +110,12 @@ static void __map_single_talitos_ptr(struct device *dev,
 				     enum dma_data_direction dir,
 				     unsigned long attrs)
 {
-	dma_addr_t dma_addr = dma_map_single_attrs(dev, data, len, dir, attrs);
 	struct talitos_private *priv = dev_get_drvdata(dev);
 	bool is_sec1 = has_ftr_sec1(priv);
+	dma_addr_t dma_addr;
 
+	/* XXX: this driver badly needs error handling. */
+	dma_map_single_attrs(dev, data, len, dir, attrs, &dma_addr);
 	to_talitos_ptr(ptr, dma_addr, len, is_sec1);
 }
 
diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
index 56c7f8637311..49a0c275546b 100644
--- a/drivers/gpu/drm/i915/i915_gem_gtt.c
+++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
@@ -566,12 +566,9 @@ static int __setup_page_dma(struct i915_address_space *vm,
 	if (unlikely(!p->page))
 		return -ENOMEM;
 
-	p->daddr = dma_map_page_attrs(vm->dma,
-				      p->page, 0, PAGE_SIZE,
-				      PCI_DMA_BIDIRECTIONAL,
-				      DMA_ATTR_SKIP_CPU_SYNC |
-				      DMA_ATTR_NO_WARN);
-	if (unlikely(dma_mapping_error(vm->dma, p->daddr))) {
+	if (dma_map_page_attrs(vm->dma, p->page, 0, PAGE_SIZE,
+			PCI_DMA_BIDIRECTIONAL,
+			DMA_ATTR_SKIP_CPU_SYNC | DMA_ATTR_NO_WARN, &p->daddr)) {
 		vm_free_page(vm, p->page);
 		return -ENOMEM;
 	}
@@ -651,12 +648,10 @@ setup_scratch_page(struct i915_address_space *vm, gfp_t gfp)
 		if (unlikely(!page))
 			goto skip;
 
-		addr = dma_map_page_attrs(vm->dma,
-					  page, 0, size,
-					  PCI_DMA_BIDIRECTIONAL,
-					  DMA_ATTR_SKIP_CPU_SYNC |
-					  DMA_ATTR_NO_WARN);
-		if (unlikely(dma_mapping_error(vm->dma, addr)))
+		if (unlikely(dma_map_page_attrs(vm->dma, page, 0, size,
+				PCI_DMA_BIDIRECTIONAL,
+				DMA_ATTR_SKIP_CPU_SYNC | DMA_ATTR_NO_WARN,
+				&addr)))
 			goto free_page;
 
 		if (unlikely(!IS_ALIGNED(addr, size)))
diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt.c b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
index dd85d790f638..b94e13499d68 100644
--- a/drivers/net/ethernet/broadcom/bnxt/bnxt.c
+++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
@@ -662,9 +662,8 @@ static struct page *__bnxt_alloc_rx_page(struct bnxt *bp, dma_addr_t *mapping,
 	if (!page)
 		return NULL;
 
-	*mapping = dma_map_page_attrs(dev, page, 0, PAGE_SIZE, bp->rx_dir,
-				      DMA_ATTR_WEAK_ORDERING);
-	if (dma_mapping_error(dev, *mapping)) {
+	if (dma_map_page_attrs(dev, page, 0, PAGE_SIZE, bp->rx_dir,
+			DMA_ATTR_WEAK_ORDERING, mapping)) {
 		__free_page(page);
 		return NULL;
 	}
@@ -682,11 +681,9 @@ static inline u8 *__bnxt_alloc_rx_data(struct bnxt *bp, dma_addr_t *mapping,
 	if (!data)
 		return NULL;
 
-	*mapping = dma_map_single_attrs(&pdev->dev, data + bp->rx_dma_offset,
-					bp->rx_buf_use_size, bp->rx_dir,
-					DMA_ATTR_WEAK_ORDERING);
-
-	if (dma_mapping_error(&pdev->dev, *mapping)) {
+	if (dma_map_single_attrs(&pdev->dev, data + bp->rx_dma_offset,
+			bp->rx_buf_use_size, bp->rx_dir, DMA_ATTR_WEAK_ORDERING,
+			mapping)) {
 		kfree(data);
 		data = NULL;
 	}
@@ -787,10 +784,9 @@ static inline int bnxt_alloc_rx_page(struct bnxt *bp,
 			return -ENOMEM;
 	}
 
-	mapping = dma_map_page_attrs(&pdev->dev, page, offset,
-				     BNXT_RX_PAGE_SIZE, PCI_DMA_FROMDEVICE,
-				     DMA_ATTR_WEAK_ORDERING);
-	if (dma_mapping_error(&pdev->dev, mapping)) {
+	if (dma_map_page_attrs(&pdev->dev, page, offset,
+			BNXT_RX_PAGE_SIZE, PCI_DMA_FROMDEVICE,
+			DMA_ATTR_WEAK_ORDERING, &mapping)) {
 		__free_page(page);
 		return -EIO;
 	}
diff --git a/drivers/net/ethernet/cavium/thunder/nicvf_queues.c b/drivers/net/ethernet/cavium/thunder/nicvf_queues.c
index 187a249ff2d1..fd762b5b233d 100644
--- a/drivers/net/ethernet/cavium/thunder/nicvf_queues.c
+++ b/drivers/net/ethernet/cavium/thunder/nicvf_queues.c
@@ -213,17 +213,18 @@ static inline int nicvf_alloc_rcv_buffer(struct nicvf *nic, struct rbdr *rbdr,
 	if (rbdr->is_xdp && pgcache && pgcache->dma_addr) {
 		*rbuf = pgcache->dma_addr;
 	} else {
+		dma_addr_t addr;
 		/* HW will ensure data coherency, CPU sync not required */
-		*rbuf = (u64)dma_map_page_attrs(&nic->pdev->dev, nic->rb_page,
-						nic->rb_page_offset, buf_len,
-						DMA_FROM_DEVICE,
-						DMA_ATTR_SKIP_CPU_SYNC);
-		if (dma_mapping_error(&nic->pdev->dev, (dma_addr_t)*rbuf)) {
+		if (dma_map_page_attrs(&nic->pdev->dev, nic->rb_page,
+				nic->rb_page_offset, buf_len, DMA_FROM_DEVICE,
+				DMA_ATTR_SKIP_CPU_SYNC, &addr)) {
 			if (!nic->rb_page_offset)
 				__free_pages(nic->rb_page, 0);
 			nic->rb_page = NULL;
 			return -ENOMEM;
 		}
+
+		*rbuf = addr;
 		if (pgcache)
 			pgcache->dma_addr = *rbuf + XDP_PACKET_HEADROOM;
 		nic->rb_page_offset += buf_len;
@@ -1576,10 +1577,9 @@ int nicvf_sq_append_skb(struct nicvf *nic, struct snd_queue *sq,
 	qentry = nicvf_get_nxt_sqentry(sq, qentry);
 	size = skb_is_nonlinear(skb) ? skb_headlen(skb) : skb->len;
 	/* HW will ensure data coherency, CPU sync not required */
-	dma_addr = dma_map_page_attrs(&nic->pdev->dev, virt_to_page(skb->data),
-				      offset_in_page(skb->data), size,
-				      DMA_TO_DEVICE, DMA_ATTR_SKIP_CPU_SYNC);
-	if (dma_mapping_error(&nic->pdev->dev, dma_addr)) {
+	if (dma_map_page_attrs(&nic->pdev->dev, virt_to_page(skb->data),
+			offset_in_page(skb->data), size, DMA_TO_DEVICE,
+			DMA_ATTR_SKIP_CPU_SYNC, &dma_addr)) {
 		nicvf_rollback_sq_desc(sq, qentry, subdesc_cnt);
 		return 0;
 	}
@@ -1597,12 +1597,9 @@ int nicvf_sq_append_skb(struct nicvf *nic, struct snd_queue *sq,
 
 		qentry = nicvf_get_nxt_sqentry(sq, qentry);
 		size = skb_frag_size(frag);
-		dma_addr = dma_map_page_attrs(&nic->pdev->dev,
-					      skb_frag_page(frag),
-					      frag->page_offset, size,
-					      DMA_TO_DEVICE,
-					      DMA_ATTR_SKIP_CPU_SYNC);
-		if (dma_mapping_error(&nic->pdev->dev, dma_addr)) {
+		if (dma_map_page_attrs(&nic->pdev->dev, skb_frag_page(frag),
+				frag->page_offset, size, DMA_TO_DEVICE,
+				DMA_ATTR_SKIP_CPU_SYNC, &dma_addr)) {
 			/* Free entire chain of mapped buffers
 			 * here 'i' = frags mapped + above mapped skb->data
 			 */
diff --git a/drivers/net/ethernet/intel/i40e/i40e_txrx.c b/drivers/net/ethernet/intel/i40e/i40e_txrx.c
index aef3c89ee79c..1d1515197bf7 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_txrx.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_txrx.c
@@ -1535,15 +1535,8 @@ static bool i40e_alloc_mapped_page(struct i40e_ring *rx_ring,
 	}
 
 	/* map page for use */
-	dma = dma_map_page_attrs(rx_ring->dev, page, 0,
-				 i40e_rx_pg_size(rx_ring),
-				 DMA_FROM_DEVICE,
-				 I40E_RX_DMA_ATTR);
-
-	/* if mapping failed free memory back to system since
-	 * there isn't much point in holding memory we can't use
-	 */
-	if (dma_mapping_error(rx_ring->dev, dma)) {
+	if (dma_map_page_attrs(rx_ring->dev, page, 0, i40e_rx_pg_size(rx_ring),
+			DMA_FROM_DEVICE, I40E_RX_DMA_ATTR, &dma)) {
 		__free_pages(page, i40e_rx_pg_order(rx_ring));
 		rx_ring->rx_stats.alloc_page_failed++;
 		return false;
diff --git a/drivers/net/ethernet/intel/i40e/i40e_xsk.c b/drivers/net/ethernet/intel/i40e/i40e_xsk.c
index add1e457886d..f950160c7e45 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_xsk.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_xsk.c
@@ -88,9 +88,8 @@ static int i40e_xsk_umem_dma_map(struct i40e_vsi *vsi, struct xdp_umem *umem)
 
 	dev = &pf->pdev->dev;
 	for (i = 0; i < umem->npgs; i++) {
-		dma = dma_map_page_attrs(dev, umem->pgs[i], 0, PAGE_SIZE,
-					 DMA_BIDIRECTIONAL, I40E_RX_DMA_ATTR);
-		if (dma_mapping_error(dev, dma))
+		if (dma_map_page_attrs(dev, umem->pgs[i], 0, PAGE_SIZE,
+				DMA_BIDIRECTIONAL, I40E_RX_DMA_ATTR, &dma))
 			goto out_unmap;
 
 		umem->pages[i].dma = dma;
diff --git a/drivers/net/ethernet/intel/iavf/iavf_txrx.c b/drivers/net/ethernet/intel/iavf/iavf_txrx.c
index fb9bfad96daf..e973985faf49 100644
--- a/drivers/net/ethernet/intel/iavf/iavf_txrx.c
+++ b/drivers/net/ethernet/intel/iavf/iavf_txrx.c
@@ -827,15 +827,8 @@ static bool iavf_alloc_mapped_page(struct iavf_ring *rx_ring,
 	}
 
 	/* map page for use */
-	dma = dma_map_page_attrs(rx_ring->dev, page, 0,
-				 iavf_rx_pg_size(rx_ring),
-				 DMA_FROM_DEVICE,
-				 IAVF_RX_DMA_ATTR);
-
-	/* if mapping failed free memory back to system since
-	 * there isn't much point in holding memory we can't use
-	 */
-	if (dma_mapping_error(rx_ring->dev, dma)) {
+	if (dma_map_page_attrs(rx_ring->dev, page, 0, iavf_rx_pg_size(rx_ring),
+			DMA_FROM_DEVICE, IAVF_RX_DMA_ATTR, &dma)) {
 		__free_pages(page, iavf_rx_pg_order(rx_ring));
 		rx_ring->rx_stats.alloc_page_failed++;
 		return false;
diff --git a/drivers/net/ethernet/intel/igb/igb_main.c b/drivers/net/ethernet/intel/igb/igb_main.c
index 5df88ad8ac81..355bdd0004d4 100644
--- a/drivers/net/ethernet/intel/igb/igb_main.c
+++ b/drivers/net/ethernet/intel/igb/igb_main.c
@@ -8439,15 +8439,8 @@ static bool igb_alloc_mapped_page(struct igb_ring *rx_ring,
 	}
 
 	/* map page for use */
-	dma = dma_map_page_attrs(rx_ring->dev, page, 0,
-				 igb_rx_pg_size(rx_ring),
-				 DMA_FROM_DEVICE,
-				 IGB_RX_DMA_ATTR);
-
-	/* if mapping failed free memory back to system since
-	 * there isn't much point in holding memory we can't use
-	 */
-	if (dma_mapping_error(rx_ring->dev, dma)) {
+	if (dma_map_page_attrs(rx_ring->dev, page, 0, igb_rx_pg_size(rx_ring),
+			DMA_FROM_DEVICE, IGB_RX_DMA_ATTR, &dma)) {
 		__free_pages(page, igb_rx_pg_order(rx_ring));
 
 		rx_ring->rx_stats.alloc_failed++;
diff --git a/drivers/net/ethernet/intel/igc/igc_main.c b/drivers/net/ethernet/intel/igc/igc_main.c
index 9d85707e8a81..d2cbc65cf291 100644
--- a/drivers/net/ethernet/intel/igc/igc_main.c
+++ b/drivers/net/ethernet/intel/igc/igc_main.c
@@ -1505,15 +1505,8 @@ static bool igc_alloc_mapped_page(struct igc_ring *rx_ring,
 	}
 
 	/* map page for use */
-	dma = dma_map_page_attrs(rx_ring->dev, page, 0,
-				 igc_rx_pg_size(rx_ring),
-				 DMA_FROM_DEVICE,
-				 IGC_RX_DMA_ATTR);
-
-	/* if mapping failed free memory back to system since
-	 * there isn't much point in holding memory we can't use
-	 */
-	if (dma_mapping_error(rx_ring->dev, dma)) {
+	if (dma_map_page_attrs(rx_ring->dev, page, 0, igc_rx_pg_size(rx_ring),
+			DMA_FROM_DEVICE, IGC_RX_DMA_ATTR, &dma)) {
 		__free_page(page);
 
 		rx_ring->rx_stats.alloc_failed++;
diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
index 113b38e0defb..03f172b1ec4d 100644
--- a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
+++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
@@ -1542,16 +1542,8 @@ static bool ixgbe_alloc_mapped_page(struct ixgbe_ring *rx_ring,
 	}
 
 	/* map page for use */
-	dma = dma_map_page_attrs(rx_ring->dev, page, 0,
-				 ixgbe_rx_pg_size(rx_ring),
-				 DMA_FROM_DEVICE,
-				 IXGBE_RX_DMA_ATTR);
-
-	/*
-	 * if mapping failed free memory back to system since
-	 * there isn't much point in holding memory we can't use
-	 */
-	if (dma_mapping_error(rx_ring->dev, dma)) {
+	if (dma_map_page_attrs(rx_ring->dev, page, 0, ixgbe_rx_pg_size(rx_ring),
+			DMA_FROM_DEVICE, IXGBE_RX_DMA_ATTR, &dma)) {
 		__free_pages(page, ixgbe_rx_pg_order(rx_ring));
 
 		rx_ring->rx_stats.alloc_rx_page_failed++;
diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_xsk.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_xsk.c
index 65c3e2c979d4..9de8e4890acb 100644
--- a/drivers/net/ethernet/intel/ixgbe/ixgbe_xsk.c
+++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_xsk.c
@@ -75,9 +75,8 @@ static int ixgbe_xsk_umem_dma_map(struct ixgbe_adapter *adapter,
 	dma_addr_t dma;
 
 	for (i = 0; i < umem->npgs; i++) {
-		dma = dma_map_page_attrs(dev, umem->pgs[i], 0, PAGE_SIZE,
-					 DMA_BIDIRECTIONAL, IXGBE_RX_DMA_ATTR);
-		if (dma_mapping_error(dev, dma))
+		if (dma_map_page_attrs(dev, umem->pgs[i], 0, PAGE_SIZE,
+				DMA_BIDIRECTIONAL, IXGBE_RX_DMA_ATTR, &dma))
 			goto out_unmap;
 
 		umem->pages[i].dma = dma;
diff --git a/drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c b/drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c
index 5e47ede7e832..966fefb32ad5 100644
--- a/drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c
+++ b/drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c
@@ -620,14 +620,9 @@ static bool ixgbevf_alloc_mapped_page(struct ixgbevf_ring *rx_ring,
 	}
 
 	/* map page for use */
-	dma = dma_map_page_attrs(rx_ring->dev, page, 0,
-				 ixgbevf_rx_pg_size(rx_ring),
-				 DMA_FROM_DEVICE, IXGBEVF_RX_DMA_ATTR);
-
-	/* if mapping failed free memory back to system since
-	 * there isn't much point in holding memory we can't use
-	 */
-	if (dma_mapping_error(rx_ring->dev, dma)) {
+	if (dma_map_page_attrs(rx_ring->dev, page, 0,
+			ixgbevf_rx_pg_size(rx_ring), DMA_FROM_DEVICE,
+			IXGBEVF_RX_DMA_ATTR, &dma)) {
 		__free_pages(page, ixgbevf_rx_pg_order(rx_ring));
 
 		rx_ring->rx_stats.alloc_rx_page_failed++;
diff --git a/drivers/net/ethernet/netronome/nfp/nfp_net_common.c b/drivers/net/ethernet/netronome/nfp/nfp_net_common.c
index 6bddfcfdec34..933b3cfe2234 100644
--- a/drivers/net/ethernet/netronome/nfp/nfp_net_common.c
+++ b/drivers/net/ethernet/netronome/nfp/nfp_net_common.c
@@ -60,11 +60,13 @@ void nfp_net_get_fw_version(struct nfp_net_fw_version *fw_ver,
 	put_unaligned_le32(reg, fw_ver);
 }
 
-static dma_addr_t nfp_net_dma_map_rx(struct nfp_net_dp *dp, void *frag)
+static int nfp_net_dma_map_rx(struct nfp_net_dp *dp, void *frag,
+		dma_addr_t *dma_handle)
 {
 	return dma_map_single_attrs(dp->dev, frag + NFP_NET_RX_BUF_HEADROOM,
 				    dp->fl_bufsz - NFP_NET_RX_BUF_NON_DATA,
-				    dp->rx_dma_dir, DMA_ATTR_SKIP_CPU_SYNC);
+				    dp->rx_dma_dir, DMA_ATTR_SKIP_CPU_SYNC,
+				    dma_handle);
 }
 
 static void
@@ -1188,8 +1190,7 @@ static void *nfp_net_rx_alloc_one(struct nfp_net_dp *dp, dma_addr_t *dma_addr)
 		return NULL;
 	}
 
-	*dma_addr = nfp_net_dma_map_rx(dp, frag);
-	if (dma_mapping_error(dp->dev, *dma_addr)) {
+	if (nfp_net_dma_map_rx(dp, frag, dma_addr)) {
 		nfp_net_free_frag(frag, dp->xdp_prog);
 		nn_dp_warn(dp, "Failed to map DMA RX buffer\n");
 		return NULL;
@@ -1215,8 +1216,7 @@ static void *nfp_net_napi_alloc_one(struct nfp_net_dp *dp, dma_addr_t *dma_addr)
 		frag = page_address(page);
 	}
 
-	*dma_addr = nfp_net_dma_map_rx(dp, frag);
-	if (dma_mapping_error(dp->dev, *dma_addr)) {
+	if (nfp_net_dma_map_rx(dp, frag, dma_addr)) {
 		nfp_net_free_frag(frag, dp->xdp_prog);
 		nn_dp_warn(dp, "Failed to map DMA RX buffer\n");
 		return NULL;
diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
index c08779649ac0..d70bded7aea8 100644
--- a/include/linux/dma-mapping.h
+++ b/include/linux/dma-mapping.h
@@ -224,22 +224,37 @@ static inline const struct dma_map_ops *get_dma_ops(struct device *dev)
 }
 #endif
 
-static inline dma_addr_t dma_map_single_attrs(struct device *dev, void *ptr,
-					      size_t size,
-					      enum dma_data_direction dir,
-					      unsigned long attrs)
+static __must_check inline int
+dma_map_single_attrs(struct device *dev, void *ptr, size_t size,
+		enum dma_data_direction dir, unsigned long attrs,
+		dma_addr_t *dma_handle)
+{
+	const struct dma_map_ops *ops = get_dma_ops(dev);
+
+	BUG_ON(!valid_dma_direction(dir));
+	debug_dma_map_single(dev, ptr, size);
+	*dma_handle = ops->map_page(dev, virt_to_page(ptr), offset_in_page(ptr),
+			size, dir, attrs);
+	if (*dma_handle == DMA_MAPPING_ERROR)
+		return -ENOMEM;
+
+	debug_dma_map_page(dev, virt_to_page(ptr), offset_in_page(ptr), size,
+			dir, *dma_handle, true);
+	return 0;
+}
+
+static inline dma_addr_t dma_map_single(struct device *dev, void *ptr,
+		size_t size, enum dma_data_direction dir)
 {
 	const struct dma_map_ops *ops = get_dma_ops(dev);
 	dma_addr_t addr;
 
 	BUG_ON(!valid_dma_direction(dir));
 	debug_dma_map_single(dev, ptr, size);
-	addr = ops->map_page(dev, virt_to_page(ptr),
-			     offset_in_page(ptr), size,
-			     dir, attrs);
-	debug_dma_map_page(dev, virt_to_page(ptr),
-			   offset_in_page(ptr), size,
-			   dir, addr, true);
+	addr = ops->map_page(dev, virt_to_page(ptr), offset_in_page(ptr), size,
+			dir, 0);
+	debug_dma_map_page(dev, virt_to_page(ptr), offset_in_page(ptr), size,
+			dir, addr, true);
 	return addr;
 }
 
@@ -287,19 +302,30 @@ static inline void dma_unmap_sg_attrs(struct device *dev, struct scatterlist *sg
 		ops->unmap_sg(dev, sg, nents, dir, attrs);
 }
 
-static inline dma_addr_t dma_map_page_attrs(struct device *dev,
-					    struct page *page,
-					    size_t offset, size_t size,
-					    enum dma_data_direction dir,
-					    unsigned long attrs)
+static __must_check inline int
+dma_map_page_attrs(struct device *dev, struct page *page, size_t offset,
+		size_t size, enum dma_data_direction dir, unsigned long attrs,
+		dma_addr_t *dma_handle)
+{
+	const struct dma_map_ops *ops = get_dma_ops(dev);
+
+	BUG_ON(!valid_dma_direction(dir));
+	*dma_handle = ops->map_page(dev, page, offset, size, dir, attrs);
+	if (*dma_handle == DMA_MAPPING_ERROR)
+		return -ENOMEM;
+	debug_dma_map_page(dev, page, offset, size, dir, *dma_handle, false);
+	return 0;
+}
+
+static inline dma_addr_t dma_map_page(struct device *dev, struct page *page,
+		size_t offset, size_t size, enum dma_data_direction dir)
 {
 	const struct dma_map_ops *ops = get_dma_ops(dev);
 	dma_addr_t addr;
 
 	BUG_ON(!valid_dma_direction(dir));
-	addr = ops->map_page(dev, page, offset, size, dir, attrs);
+	addr = ops->map_page(dev, page, offset, size, dir, 0);
 	debug_dma_map_page(dev, page, offset, size, dir, addr, false);
-
 	return addr;
 }
 
@@ -428,11 +454,9 @@ dma_sync_sg_for_device(struct device *dev, struct scatterlist *sg,
 
 }
 
-#define dma_map_single(d, a, s, r) dma_map_single_attrs(d, a, s, r, 0)
 #define dma_unmap_single(d, a, s, r) dma_unmap_single_attrs(d, a, s, r, 0)
 #define dma_map_sg(d, s, n, r) dma_map_sg_attrs(d, s, n, r, 0)
 #define dma_unmap_sg(d, s, n, r) dma_unmap_sg_attrs(d, s, n, r, 0)
-#define dma_map_page(d, p, o, s, r) dma_map_page_attrs(d, p, o, s, r, 0)
 #define dma_unmap_page(d, a, s, r) dma_unmap_page_attrs(d, a, s, r, 0)
 
 static inline void
-- 
2.19.1

Re: [RFC] remove the ->mapping_error method from dma_map_ops

[David Miller]

From: Christoph Hellwig <hch@lst.de>
Date: Fri,  9 Nov 2018 09:46:30 +0100

> Error reporting for the dma_map_single and dma_map_page operations is
> currently a mess.  Both APIs directly return the dma_addr_t to be used for
> the DMA, with a magic error escape that is specific to the instance and
> checked by another method provided.  This has a few downsides:
> 
>  - the error check is easily forgotten and a __must_check marker doesn't
>    help as the value always is consumed anyway
>  - the error checking requires another indirect call, which have gotten
>    incredibly expensive
>  - a lot of code is wasted on implementing these methods
> 
> The historical reason for this is that people thought DMA mappings would
> not fail when the API was created, which sounds like a really bad
> assumption in retrospective, and then we tried to cram error handling
> onto it later on.
> 
> There basically are two variants:  the error code is 0 because the
> implementation will never return 0 as a valid DMA address, or the error
> code is all-F as the implementation won't ever return an address that
> high.  The old AMD GART is the only one not falling into these two camps
> as it picks sort of a relative zero relative to where it is mapped.
> 
> The 0 return doesn't work for a lot of IOMMUs that start allocating
> bus space from address zero, so we can't consolidate on that, but I think
> we can move everyone to all-Fs, which the patch here does.  The reason
> for that is that there is only one way to ever get this address: by
> doing a 1-byte long, 1-byte aligned mapping, but all our mappings
> are not only longer but generally aligned, and the mappings have to
> keep at least the basic alignment.  Please try to poke holes into this
> idea as it would simplify our logic a lot, and also allow to change
> at least the not so commonly used yet dma_map_single_attrs and
> dma_map_page_attrs to actually return an error code and further improve
> the error handling flow in the drivers.

I have no problem with patch #1, it looks great.

But patch #2 on the other hand, not so much.

I hate seeing values returned by reference, it adds cost especially
on cpus where all argments and return values fit in registers (we end
up forcing a stack slot and memory references).

And we don't need it here.

DMA addresses are like pointers, and therefore we can return errors and
valid success values in the same dma_addr_t just fine.  PTR_ERR() --> DMA_ERR(),
IS_PTR_ERR() --> IS_DMA_ERR, etc.

Re: [RFC] remove the ->mapping_error method from dma_map_ops

[Christoph Hellwig]

On Fri, Nov 09, 2018 at 03:12:34PM -0800, David Miller wrote:
> But patch #2 on the other hand, not so much.
> 
> I hate seeing values returned by reference, it adds cost especially
> on cpus where all argments and return values fit in registers (we end
> up forcing a stack slot and memory references).
> 
> And we don't need it here.
> 
> DMA addresses are like pointers, and therefore we can return errors and
> valid success values in the same dma_addr_t just fine.  PTR_ERR() --> DMA_ERR(),
> IS_PTR_ERR() --> IS_DMA_ERR, etc.

In the end this is an inline function, so with a decently smart
compiler the generated code shouldn't change too much.  The big problem
that prompted me to come up with this patch is that not handling failure
from dma_map* in a swiotlb setup can lead to grave data corruption, and
we have no easy way to force error checking on these return values.

I've added a few of the static typechecking suspect if they have a
better idea on how to make the return value of dma_map_single/pages
in a way that we get warnings if dma_mapping_error isn't called on them.
But I can't really think of a good way.