remove the ->mapping_error method from dma_map_ops V3

remove the ->mapping_error method from dma_map_ops V3

[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 direct mappings that have ram at address
zero and 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.

A git tree is also available here:

    git://git.infradead.org/users/hch/misc.git dma-mapping-error.3

Gitweb:

    http://git.infradead.org/users/hch/misc.git/shortlog/refs/heads/dma-mapping-error.3

Changes since v2:
 - fix a compile error in the ia64 sba_iommu driver
 - return an errno value from dma_mapping_error

Changes since v1:
 - dropped the signature change
 - split into multiple patches
 - fixed the iova allocator return check in amd-iommu
 - remove EMERGENCY_PAGES in amd_gart and calgary

[PATCH 01/23] dma-mapping: provide a generic DMA_MAPPING_ERROR

[Christoph Hellwig]

Error handling of the dma_map_single and dma_map_page APIs is a little
problematic at the moment, in that we use different encodings in the
returned dma_addr_t to indicate an error.  That means we require an
additional indirect call to figure out if a dma mapping call returned
an error, and a lot of boilerplate code to implement these semantics.

Instead return the maximum addressable value as the error.  As long
as we don't allow mapping single-byte ranges with single-byte alignment
this value can never be a valid return.  Additionaly if drivers do
not check the return value from the dma_map* routines this values means
they will generally not be pointed to actual memory.

Once the default value is added here we can start removing the
various mapping_error methods and just rely on this generic check.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 include/linux/dma-mapping.h | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
index 0f81c713f6e9..46bd612d929e 100644
--- a/include/linux/dma-mapping.h
+++ b/include/linux/dma-mapping.h
@@ -133,6 +133,8 @@ struct dma_map_ops {
 	u64 (*get_required_mask)(struct device *dev);
 };
 
+#define DMA_MAPPING_ERROR		(~(dma_addr_t)0)
+
 extern const struct dma_map_ops dma_direct_ops;
 extern const struct dma_map_ops dma_virt_ops;
 
@@ -576,6 +578,10 @@ 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 (dma_addr == DMA_MAPPING_ERROR)
+		return 1;
+
 	if (ops->mapping_error)
 		return ops->mapping_error(dev, dma_addr);
 	return 0;
-- 
2.19.1

[PATCH 02/23] dma-direct: remove the mapping_error dma_map_ops method

[Christoph Hellwig]

The dma-direct code already returns (~(dma_addr_t)0x0) on mapping
failures, so we can switch over to returning DMA_MAPPING_ERROR and let
the core dma-mapping code handle the rest.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/powerpc/kernel/dma-swiotlb.c |  1 -
 include/linux/dma-direct.h        |  3 ---
 kernel/dma/direct.c               |  8 +-------
 kernel/dma/swiotlb.c              | 11 +++++------
 4 files changed, 6 insertions(+), 17 deletions(-)

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/include/linux/dma-direct.h b/include/linux/dma-direct.h
index 9e66bfe369aa..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		(~(dma_addr_t)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/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 045930e32c0e..ff1ce81bb623 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;
@@ -680,7 +680,7 @@ dma_addr_t swiotlb_map_page(struct device *dev, struct page *page,
 
 	if (!dev_is_dma_coherent(dev) &&
 	    (attrs & DMA_ATTR_SKIP_CPU_SYNC) == 0 &&
-	    dev_addr != DIRECT_MAPPING_ERROR)
+	    dev_addr != DMA_MAPPING_ERROR)
 		arch_sync_dma_for_device(dev, phys, size, dir);
 
 	return dev_addr;
@@ -789,7 +789,7 @@ 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;
 	}
@@ -869,7 +869,6 @@ 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

[PATCH 03/23] arm: remove the mapping_error dma_map_ops method

[Christoph Hellwig]

Arm already returns (~(dma_addr_t)0x0) on mapping failures, so we can
switch over to returning DMA_MAPPING_ERROR and let the core dma-mapping
code handle the rest.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/arm/common/dmabounce.c      | 12 +++-------
 arch/arm/include/asm/dma-iommu.h |  2 --
 arch/arm/mm/dma-mapping.c        | 39 ++++++++++++--------------------
 3 files changed, 18 insertions(+), 35 deletions(-)

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,
 };
 
-- 
2.19.1

[PATCH 04/23] powerpc/iommu: remove the mapping_error dma_map_ops method

[Christoph Hellwig]

The powerpc iommu code already returns (~(dma_addr_t)0x0) on mapping
failures, so we can switch over to returning DMA_MAPPING_ERROR and let
the core dma-mapping code handle the rest.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/powerpc/include/asm/iommu.h     |  4 ----
 arch/powerpc/kernel/dma-iommu.c      |  6 ------
 arch/powerpc/kernel/iommu.c          | 28 ++++++++++++++--------------
 arch/powerpc/platforms/cell/iommu.c  |  1 -
 arch/powerpc/platforms/pseries/vio.c |  3 +--
 5 files changed, 15 insertions(+), 27 deletions(-)

diff --git a/arch/powerpc/include/asm/iommu.h b/arch/powerpc/include/asm/iommu.h
index 35db0cbc9222..55312990d1d2 100644
--- a/arch/powerpc/include/asm/iommu.h
+++ b/arch/powerpc/include/asm/iommu.h
@@ -143,8 +143,6 @@ 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)
 {
@@ -242,8 +240,6 @@ static inline int __init tce_iommu_bus_notifier_init(void)
 }
 #endif /* !CONFIG_IOMMU_API */
 
-int dma_iommu_mapping_error(struct device *dev, dma_addr_t dma_addr);
-
 #else
 
 static inline void *get_iommu_table_base(struct device *dev)
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/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,
 };
 
 /**
-- 
2.19.1

[PATCH 05/23] mips/jazz: remove the mapping_error dma_map_ops method

[Christoph Hellwig]

The Jazz iommu code already returns (~(dma_addr_t)0x0) on mapping
failures, so we can switch over to returning DMA_MAPPING_ERROR and
let the core dma-mapping code handle the rest.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/mips/include/asm/jazzdma.h |  6 ------
 arch/mips/jazz/jazzdma.c        | 16 +++++-----------
 2 files changed, 5 insertions(+), 17 deletions(-)

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);
-- 
2.19.1

[PATCH 06/23] s390: remove the mapping_error dma_map_ops method

[Christoph Hellwig]

S390 already returns (~(dma_addr_t)0x0) on mapping failures, so we can
switch over to returning DMA_MAPPING_ERROR and let the core dma-mapping
code handle the rest.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/s390/pci/pci_dma.c | 18 +++++-------------
 1 file changed, 5 insertions(+), 13 deletions(-)

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);
-- 
2.19.1

[PATCH 07/23] sparc: remove the mapping_error dma_map_ops method

[Christoph Hellwig]

Sparc already returns (~(dma_addr_t)0x0) on mapping failures, so we can
switch over to returning DMA_MAPPING_ERROR and let the core dma-mapping
code handle the rest.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/sparc/kernel/iommu.c        | 12 +++---------
 arch/sparc/kernel/iommu_common.h |  2 --
 arch/sparc/kernel/pci_sun4v.c    | 14 ++++----------
 3 files changed, 7 insertions(+), 21 deletions(-)

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)
-- 
2.19.1

[PATCH 08/23] parisc/ccio: remove the mapping_error dma_map_ops method

[Christoph Hellwig]

The CCIO iommu code already returns (~(dma_addr_t)0x0) on mapping
failures, so we can switch over to returning DMA_MAPPING_ERROR and let
the core dma-mapping code handle the rest.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 drivers/parisc/ccio-dma.c | 10 +---------
 1 file changed, 1 insertion(+), 9 deletions(-)

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
-- 
2.19.1

[PATCH 09/23] parisc/sba_iommu: remove the mapping_error dma_map_ops method

[Christoph Hellwig]

The SBA iommu code already returns (~(dma_addr_t)0x0) on mapping
failures, so we can switch over to returning DMA_MAPPING_ERROR and let
the core dma-mapping code handle the rest.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 drivers/parisc/sba_iommu.c | 10 +---------
 1 file changed, 1 insertion(+), 9 deletions(-)

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,
 };
 
 
-- 
2.19.1

[PATCH 10/23] arm64: remove the dummy_dma_ops mapping_error method

[Christoph Hellwig]

Just return DMA_MAPPING_ERROR from __dummy_map_page and let the core
dma-mapping code handle the rest.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/arm64/mm/dma-mapping.c | 8 +-------
 1 file changed, 1 insertion(+), 7 deletions(-)

diff --git a/arch/arm64/mm/dma-mapping.c b/arch/arm64/mm/dma-mapping.c
index a3ac26284845..fdc26ea5036c 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);
-- 
2.19.1

[PATCH 11/23] alpha: remove the mapping_error dma_map_ops method

[Christoph Hellwig]

Return DMA_MAPPING_ERROR instead of 0 on a dma mapping failure and let
the core dma-mapping code handle the rest.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/alpha/kernel/pci_iommu.c | 14 ++++----------
 1 file changed, 4 insertions(+), 10 deletions(-)

diff --git a/arch/alpha/kernel/pci_iommu.c b/arch/alpha/kernel/pci_iommu.c
index 46e08e0d9181..e1716e0d92fd 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;
@@ -455,7 +455,7 @@ static void *alpha_pci_alloc_coherent(struct device *dev, size_t size,
 	memset(cpu_addr, 0, size);
 
 	*dma_addrp = pci_map_single_1(pdev, cpu_addr, size, 0);
-	if (*dma_addrp == 0) {
+	if (*dma_addrp == DMA_MAPPING_ERROR) {
 		free_pages((unsigned long)cpu_addr, order);
 		if (alpha_mv.mv_pci_tbi || (gfp & GFP_DMA))
 			return NULL;
@@ -671,7 +671,7 @@ static int alpha_pci_map_sg(struct device *dev, struct scatterlist *sg,
 		sg->dma_address
 		  = pci_map_single_1(pdev, SG_ENT_VIRT_ADDRESS(sg),
 				     sg->length, dac_allowed);
-		return sg->dma_address != 0;
+		return sg->dma_address != DMA_MAPPING_ERROR;
 	}
 
 	start = sg;
@@ -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);
-- 
2.19.1

[PATCH 12/23] ia64/sba_iommu: improve internal map_page users

[Christoph Hellwig]

Remove the odd sba_{un,}map_single_attrs wrappers, check errors
everywhere.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/ia64/hp/common/sba_iommu.c | 73 +++++++++++++--------------------
 1 file changed, 29 insertions(+), 44 deletions(-)

diff --git a/arch/ia64/hp/common/sba_iommu.c b/arch/ia64/hp/common/sba_iommu.c
index e8a93b07283e..c56f28c98102 100644
--- a/arch/ia64/hp/common/sba_iommu.c
+++ b/arch/ia64/hp/common/sba_iommu.c
@@ -907,11 +907,12 @@ sba_mark_invalid(struct ioc *ioc, dma_addr_t iova, size_t byte_cnt)
 }
 
 /**
- * sba_map_single_attrs - map one buffer and return IOVA for DMA
+ * sba_map_page - map one buffer and return IOVA for DMA
  * @dev: instance of PCI owned by the driver that's asking.
- * @addr:  driver buffer to map.
- * @size:  number of bytes to map in driver buffer.
- * @dir:  R/W or both.
+ * @page: page to map
+ * @poff: offset into page
+ * @size: number of bytes to map
+ * @dir: dma direction
  * @attrs: optional dma attributes
  *
  * See Documentation/DMA-API-HOWTO.txt
@@ -944,7 +945,7 @@ static dma_addr_t sba_map_page(struct device *dev, struct page *page,
  		** Device is bit capable of DMA'ing to the buffer...
 		** just return the PCI address of ptr
  		*/
-		DBG_BYPASS("sba_map_single_attrs() bypass mask/addr: "
+		DBG_BYPASS("sba_map_page() bypass mask/addr: "
 			   "0x%lx/0x%lx\n",
 		           to_pci_dev(dev)->dma_mask, pci_addr);
 		return pci_addr;
@@ -966,7 +967,7 @@ static dma_addr_t sba_map_page(struct device *dev, struct page *page,
 
 #ifdef ASSERT_PDIR_SANITY
 	spin_lock_irqsave(&ioc->res_lock, flags);
-	if (sba_check_pdir(ioc,"Check before sba_map_single_attrs()"))
+	if (sba_check_pdir(ioc,"Check before sba_map_page()"))
 		panic("Sanity check failed");
 	spin_unlock_irqrestore(&ioc->res_lock, flags);
 #endif
@@ -997,20 +998,12 @@ static dma_addr_t sba_map_page(struct device *dev, struct page *page,
 	/* form complete address */
 #ifdef ASSERT_PDIR_SANITY
 	spin_lock_irqsave(&ioc->res_lock, flags);
-	sba_check_pdir(ioc,"Check after sba_map_single_attrs()");
+	sba_check_pdir(ioc,"Check after sba_map_page()");
 	spin_unlock_irqrestore(&ioc->res_lock, flags);
 #endif
 	return SBA_IOVA(ioc, iovp, offset);
 }
 
-static dma_addr_t sba_map_single_attrs(struct device *dev, void *addr,
-				       size_t size, enum dma_data_direction dir,
-				       unsigned long attrs)
-{
-	return sba_map_page(dev, virt_to_page(addr),
-			    (unsigned long)addr & ~PAGE_MASK, size, dir, attrs);
-}
-
 #ifdef ENABLE_MARK_CLEAN
 static SBA_INLINE void
 sba_mark_clean(struct ioc *ioc, dma_addr_t iova, size_t size)
@@ -1036,7 +1029,7 @@ sba_mark_clean(struct ioc *ioc, dma_addr_t iova, size_t size)
 #endif
 
 /**
- * sba_unmap_single_attrs - unmap one IOVA and free resources
+ * sba_unmap_page - unmap one IOVA and free resources
  * @dev: instance of PCI owned by the driver that's asking.
  * @iova:  IOVA of driver buffer previously mapped.
  * @size:  number of bytes mapped in driver buffer.
@@ -1063,7 +1056,7 @@ static void sba_unmap_page(struct device *dev, dma_addr_t iova, size_t size,
 		/*
 		** Address does not fall w/in IOVA, must be bypassing
 		*/
-		DBG_BYPASS("sba_unmap_single_attrs() bypass addr: 0x%lx\n",
+		DBG_BYPASS("sba_unmap_page() bypass addr: 0x%lx\n",
 			   iova);
 
 #ifdef ENABLE_MARK_CLEAN
@@ -1114,12 +1107,6 @@ static void sba_unmap_page(struct device *dev, dma_addr_t iova, size_t size,
 #endif /* DELAYED_RESOURCE_CNT == 0 */
 }
 
-void sba_unmap_single_attrs(struct device *dev, dma_addr_t iova, size_t size,
-			    enum dma_data_direction dir, unsigned long attrs)
-{
-	sba_unmap_page(dev, iova, size, dir, attrs);
-}
-
 /**
  * sba_alloc_coherent - allocate/map shared mem for DMA
  * @dev: instance of PCI owned by the driver that's asking.
@@ -1132,30 +1119,24 @@ static void *
 sba_alloc_coherent(struct device *dev, size_t size, dma_addr_t *dma_handle,
 		   gfp_t flags, unsigned long attrs)
 {
+	struct page *page;
 	struct ioc *ioc;
+	int node = -1;
 	void *addr;
 
 	ioc = GET_IOC(dev);
 	ASSERT(ioc);
-
 #ifdef CONFIG_NUMA
-	{
-		struct page *page;
-
-		page = alloc_pages_node(ioc->node, flags, get_order(size));
-		if (unlikely(!page))
-			return NULL;
-
-		addr = page_address(page);
-	}
-#else
-	addr = (void *) __get_free_pages(flags, get_order(size));
+	node = ioc->node;
 #endif
-	if (unlikely(!addr))
+
+	page = alloc_pages_node(node, flags, get_order(size));
+	if (unlikely(!page))
 		return NULL;
 
+	addr = page_address(page);
 	memset(addr, 0, size);
-	*dma_handle = virt_to_phys(addr);
+	*dma_handle = page_to_phys(page);
 
 #ifdef ALLOW_IOV_BYPASS
 	ASSERT(dev->coherent_dma_mask);
@@ -1174,9 +1155,10 @@ sba_alloc_coherent(struct device *dev, size_t size, dma_addr_t *dma_handle,
 	 * If device can't bypass or bypass is disabled, pass the 32bit fake
 	 * device to map single to get an iova mapping.
 	 */
-	*dma_handle = sba_map_single_attrs(&ioc->sac_only_dev->dev, addr,
-					   size, 0, 0);
-
+	*dma_handle = sba_map_page(&ioc->sac_only_dev->dev, page, 0, size,
+			DMA_BIDIRECTIONAL, 0);
+	if (dma_mapping_error(dev, *dma_handle))
+		return NULL;
 	return addr;
 }
 
@@ -1193,7 +1175,7 @@ sba_alloc_coherent(struct device *dev, size_t size, dma_addr_t *dma_handle,
 static void sba_free_coherent(struct device *dev, size_t size, void *vaddr,
 			      dma_addr_t dma_handle, unsigned long attrs)
 {
-	sba_unmap_single_attrs(dev, dma_handle, size, 0, 0);
+	sba_unmap_page(dev, dma_handle, size, 0, 0);
 	free_pages((unsigned long) vaddr, get_order(size));
 }
 
@@ -1483,7 +1465,10 @@ static int sba_map_sg_attrs(struct device *dev, struct scatterlist *sglist,
 	/* Fast path single entry scatterlists. */
 	if (nents == 1) {
 		sglist->dma_length = sglist->length;
-		sglist->dma_address = sba_map_single_attrs(dev, sba_sg_address(sglist), sglist->length, dir, attrs);
+		sglist->dma_address = sba_map_page(dev, sg_page(sglist),
+				sglist->offset, sglist->length, dir, attrs);
+		if (dma_mapping_error(dev, sglist->dma_address))
+			return 0;
 		return 1;
 	}
 
@@ -1572,8 +1557,8 @@ static void sba_unmap_sg_attrs(struct device *dev, struct scatterlist *sglist,
 
 	while (nents && sglist->dma_length) {
 
-		sba_unmap_single_attrs(dev, sglist->dma_address,
-				       sglist->dma_length, dir, attrs);
+		sba_unmap_page(dev, sglist->dma_address, sglist->dma_length,
+			       dir, attrs);
 		sglist = sg_next(sglist);
 		nents--;
 	}
-- 
2.19.1

[PATCH 13/23] ia64/sba_iommu: remove the mapping_error dma_map_ops method

[Christoph Hellwig]

Return DMA_MAPPING_ERROR instead of 0 on a dma mapping failure and let
the core dma-mapping code handle the rest.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/ia64/hp/common/sba_iommu.c | 8 +-------
 1 file changed, 1 insertion(+), 7 deletions(-)

diff --git a/arch/ia64/hp/common/sba_iommu.c b/arch/ia64/hp/common/sba_iommu.c
index c56f28c98102..0d21c0b5b23d 100644
--- a/arch/ia64/hp/common/sba_iommu.c
+++ b/arch/ia64/hp/common/sba_iommu.c
@@ -974,7 +974,7 @@ 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;
 
@@ -2155,11 +2155,6 @@ 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
@@ -2193,7 +2188,6 @@ 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)
-- 
2.19.1

[PATCH 14/23] ia64/sn: remove the mapping_error dma_map_ops method

[Christoph Hellwig]

Return DMA_MAPPING_ERROR instead of 0 on a dma mapping failure and let
the core dma-mapping code handle the rest.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/ia64/sn/pci/pci_dma.c | 8 +-------
 1 file changed, 1 insertion(+), 7 deletions(-)

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,
 };
-- 
2.19.1

[PATCH 15/23] x86/amd_gart: remove the mapping_error dma_map_ops method

[Christoph Hellwig]

Return DMA_MAPPING_ERROR instead of the magic bad_dma_addr on a dma
mapping failure and let the core dma-mapping code handle the rest.

Remove the magic EMERGENCY_PAGES that the bad_dma_addr gets redirected to.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/x86/kernel/amd_gart_64.c | 39 ++++++-----------------------------
 1 file changed, 6 insertions(+), 33 deletions(-)

diff --git a/arch/x86/kernel/amd_gart_64.c b/arch/x86/kernel/amd_gart_64.c
index 3f9d1b4019bb..4e733de93f41 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
@@ -74,8 +72,6 @@ static u32 gart_unmapped_entry;
 	(((x) & 0xfffff000) | (((x) >> 32) << 4) | GPTE_VALID | GPTE_COHERENT)
 #define GPTE_DECODE(x) (((x) & 0xfffff000) | (((u64)(x) & 0xff0) << 28))
 
-#define EMERGENCY_PAGES 32 /* = 128KB */
-
 #ifdef CONFIG_AGP
 #define AGPEXTERN extern
 #else
@@ -184,14 +180,6 @@ static void iommu_full(struct device *dev, size_t size, int dir)
 	 */
 
 	dev_err(dev, "PCI-DMA: Out of IOMMU space for %lu bytes\n", size);
-
-	if (size > PAGE_SIZE*EMERGENCY_PAGES) {
-		if (dir == PCI_DMA_FROMDEVICE || dir == PCI_DMA_BIDIRECTIONAL)
-			panic("PCI-DMA: Memory would be corrupted\n");
-		if (dir == PCI_DMA_TODEVICE || dir == PCI_DMA_BIDIRECTIONAL)
-			panic(KERN_ERR
-				"PCI-DMA: Random memory would be DMAed\n");
-	}
 #ifdef CONFIG_IOMMU_LEAK
 	dump_leak();
 #endif
@@ -220,7 +208,7 @@ 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 +217,7 @@ 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++) {
@@ -271,7 +259,7 @@ static void gart_unmap_page(struct device *dev, dma_addr_t dma_addr,
 	int npages;
 	int i;
 
-	if (dma_addr < iommu_bus_base + EMERGENCY_PAGES*PAGE_SIZE ||
+	if (dma_addr == DMA_MAPPING_ERROR ||
 	    dma_addr >= iommu_bus_base + iommu_size)
 		return;
 
@@ -315,7 +303,7 @@ 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 +459,7 @@ 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 +478,7 @@ 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 +495,6 @@ 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 +678,6 @@ 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,
 };
 
@@ -784,19 +766,12 @@ int __init gart_iommu_init(void)
 	}
 #endif
 
-	/*
-	 * Out of IOMMU space handling.
-	 * Reserve some invalid pages at the beginning of the GART.
-	 */
-	bitmap_set(iommu_gart_bitmap, 0, EMERGENCY_PAGES);
-
 	pr_info("PCI-DMA: Reserving %luMB of IOMMU area in the AGP aperture\n",
 	       iommu_size >> 20);
 
 	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);
 
 	/*
@@ -838,8 +813,6 @@ int __init gart_iommu_init(void)
 	if (!scratch)
 		panic("Cannot allocate iommu scratch page");
 	gart_unmapped_entry = GPTE_ENCODE(__pa(scratch));
-	for (i = EMERGENCY_PAGES; i < iommu_pages; i++)
-		iommu_gatt_base[i] = gart_unmapped_entry;
 
 	flush_gart();
 	dma_ops = &gart_dma_ops;
-- 
2.19.1

[PATCH 16/23] x86/calgary: remove the mapping_error dma_map_ops method

[Christoph Hellwig]

Return DMA_MAPPING_ERROR instead of the magic bad_dma_addr on a dma
mapping failure and let the core dma-mapping code handle the rest.

Remove the magic EMERGENCY_PAGES that the bad_dma_addr gets redirected to.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/x86/kernel/pci-calgary_64.c | 29 +++++++----------------------
 1 file changed, 7 insertions(+), 22 deletions(-)

diff --git a/arch/x86/kernel/pci-calgary_64.c b/arch/x86/kernel/pci-calgary_64.c
index bbfc8b1e9104..e76ec1b8ed1f 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
@@ -157,8 +155,6 @@ static const unsigned long phb_debug_offsets[] = {
 
 #define PHB_DEBUG_STUFF_OFFSET	0x0020
 
-#define EMERGENCY_PAGES 32 /* = 128KB */
-
 unsigned int specified_table_size = TCE_TABLE_SIZE_UNSPECIFIED;
 static int translate_empty_slots __read_mostly = 0;
 static int calgary_detected __read_mostly = 0;
@@ -255,7 +251,7 @@ 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;
 		}
 	}
 
@@ -274,11 +270,10 @@ static dma_addr_t iommu_alloc(struct device *dev, struct iommu_table *tbl,
 	dma_addr_t ret;
 
 	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 */
@@ -298,8 +293,7 @@ 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);
-	if (unlikely(dma_addr < badend)) {
+	if (unlikely(dma_addr == DMA_MAPPING_ERROR)) {
 		WARN(1, KERN_ERR "Calgary: driver tried unmapping bad DMA "
 		       "address 0x%Lx\n", dma_addr);
 		return;
@@ -383,7 +377,7 @@ 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 +395,7 @@ 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 +448,7 @@ 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 +473,6 @@ 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 +480,6 @@ 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,
 };
 
@@ -739,9 +727,6 @@ static void __init calgary_reserve_regions(struct pci_dev *dev)
 	u64 start;
 	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);
-
 	/* avoid the BIOS/VGA first 640KB-1MB region */
 	/* for CalIOC2 - avoid the entire first MB */
 	if (is_calgary(dev->device)) {
-- 
2.19.1

[PATCH 17/23] iommu: remove the mapping_error dma_map_ops method

[Christoph Hellwig]

Return DMA_MAPPING_ERROR instead of 0 on a dma mapping failure and let
the core dma-mapping code handle the rest.

Note that the existing code used AMD_IOMMU_MAPPING_ERROR to check from
a 0 return from the IOVA allocator, which is replaced with an explicit
0 as in the implementation and other users of that interface.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 drivers/iommu/amd_iommu.c | 18 +++++-------------
 1 file changed, 5 insertions(+), 13 deletions(-)

diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c
index 1167ff0416cf..c5d6c7c42b0a 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)
 		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)
-- 
2.19.1

[PATCH 18/23] iommu/intel: small map_page cleanup

[Christoph Hellwig]

Pass the page + offset to the low-level __iommu_map_single helper
(which gets renamed to fit the new calling conventions) as both
callers have the page at hand.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 drivers/iommu/intel-iommu.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index 41a4b8808802..66b4444398ae 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -3597,9 +3597,11 @@ static int iommu_no_mapping(struct device *dev)
 	return 0;
 }
 
-static dma_addr_t __intel_map_single(struct device *dev, phys_addr_t paddr,
-				     size_t size, int dir, u64 dma_mask)
+static dma_addr_t __intel_map_page(struct device *dev, struct page *page,
+				   unsigned long offset, size_t size, int dir,
+				   u64 dma_mask)
 {
+	phys_addr_t paddr = page_to_phys(page) + offset;
 	struct dmar_domain *domain;
 	phys_addr_t start_paddr;
 	unsigned long iova_pfn;
@@ -3661,8 +3663,7 @@ 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,
-				  dir, *dev->dma_mask);
+	return __intel_map_page(dev, page, offset, size, dir, *dev->dma_mask);
 }
 
 static void intel_unmap(struct device *dev, dma_addr_t dev_addr, size_t size)
@@ -3753,9 +3754,8 @@ static void *intel_alloc_coherent(struct device *dev, size_t size,
 		return NULL;
 	memset(page_address(page), 0, size);
 
-	*dma_handle = __intel_map_single(dev, page_to_phys(page), size,
-					 DMA_BIDIRECTIONAL,
-					 dev->coherent_dma_mask);
+	*dma_handle = __intel_map_page(dev, page, 0, size, DMA_BIDIRECTIONAL,
+				       dev->coherent_dma_mask);
 	if (*dma_handle)
 		return page_address(page);
 	if (!dma_release_from_contiguous(dev, page, size >> PAGE_SHIFT))
-- 
2.19.1

[PATCH 19/23] iommu/vt-d: remove the mapping_error dma_map_ops method

[Christoph Hellwig]

Return DMA_MAPPING_ERROR instead of 0 on a dma mapping failure and let
the core dma-mapping code handle the rest.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 drivers/iommu/intel-iommu.c | 12 +++---------
 1 file changed, 3 insertions(+), 9 deletions(-)

diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index 66b4444398ae..0ad67d65bbce 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -3617,7 +3617,7 @@ static dma_addr_t __intel_map_page(struct device *dev, struct page *page,
 
 	domain = get_valid_domain_for_dev(dev);
 	if (!domain)
-		return 0;
+		return DMA_MAPPING_ERROR;
 
 	iommu = domain_get_iommu(domain);
 	size = aligned_nrpages(paddr, size);
@@ -3655,7 +3655,7 @@ static dma_addr_t __intel_map_page(struct device *dev, struct page *page,
 		free_iova_fast(&domain->iovad, iova_pfn, dma_to_mm_pfn(size));
 	pr_err("Device %s request: %zx@%llx dir %d --- failed\n",
 		dev_name(dev), size, (unsigned long long)paddr, dir);
-	return 0;
+	return DMA_MAPPING_ERROR;
 }
 
 static dma_addr_t intel_map_page(struct device *dev, struct page *page,
@@ -3756,7 +3756,7 @@ static void *intel_alloc_coherent(struct device *dev, size_t size,
 
 	*dma_handle = __intel_map_page(dev, page, 0, size, DMA_BIDIRECTIONAL,
 				       dev->coherent_dma_mask);
-	if (*dma_handle)
+	if (*dma_handle != DMA_MAPPING_ERROR)
 		return page_address(page);
 	if (!dma_release_from_contiguous(dev, page, size >> PAGE_SHIFT))
 		__free_pages(page, order);
@@ -3865,11 +3865,6 @@ 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 +3872,6 @@ 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,
 };
 
-- 
2.19.1

[PATCH 20/23] iommu/dma-iommu: remove the mapping_error dma_map_ops method

[Christoph Hellwig]

Return DMA_MAPPING_ERROR instead of 0 on a dma mapping failure and let
the core dma-mapping code handle the rest.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/arm64/mm/dma-mapping.c |  7 +++----
 drivers/iommu/dma-iommu.c   | 23 ++++++++---------------
 include/linux/dma-iommu.h   |  1 -
 3 files changed, 11 insertions(+), 20 deletions(-)

diff --git a/arch/arm64/mm/dma-mapping.c b/arch/arm64/mm/dma-mapping.c
index fdc26ea5036c..4cc70029cf8d 100644
--- a/arch/arm64/mm/dma-mapping.c
+++ b/arch/arm64/mm/dma-mapping.c
@@ -397,7 +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
@@ -414,7 +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;
@@ -574,7 +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;
@@ -657,7 +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/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/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);
-- 
2.19.1

[PATCH 21/23] xen-swiotlb: remove the mapping_error dma_map_ops method

[Christoph Hellwig]

Return DMA_MAPPING_ERROR instead of 0 on a dma mapping failure and let
the core dma-mapping code handle the rest.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 drivers/xen/swiotlb-xen.c | 12 ++----------
 1 file changed, 2 insertions(+), 10 deletions(-)

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,
 };
-- 
2.19.1

[PATCH 22/23] dma-mapping: remove the mapping_error dma_map_ops method

[Christoph Hellwig]

No users left except for vmd which just forwards it.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 drivers/pci/controller/vmd.c | 6 ------
 include/linux/dma-mapping.h  | 7 -------
 2 files changed, 13 deletions(-)

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/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
index 46bd612d929e..2adef56c6069 100644
--- a/include/linux/dma-mapping.h
+++ b/include/linux/dma-mapping.h
@@ -128,7 +128,6 @@ 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);
 };
@@ -575,15 +574,9 @@ 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 (dma_addr == DMA_MAPPING_ERROR)
 		return 1;
-
-	if (ops->mapping_error)
-		return ops->mapping_error(dev, dma_addr);
 	return 0;
 }
 
-- 
2.19.1

[PATCH 23/23] dma-mapping: return an error code from dma_mapping_error

[Christoph Hellwig]

Currently dma_mapping_error returns a boolean as int, with 1 meaning
error.  This is rather unusual and many callers have to convert it to
errno value.  The callers are highly inconsistent with error codes
ranging from -ENOMEM over -EIO, -EINVAL and -EFAULT ranging to -EAGAIN.
Return -ENOMEM which seems to be what the largest number of callers
convert it to, and which also matches the typical error case where
we are out of resources.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 include/linux/dma-mapping.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
index 2adef56c6069..b5bd25fc1f81 100644
--- a/include/linux/dma-mapping.h
+++ b/include/linux/dma-mapping.h
@@ -576,7 +576,7 @@ static inline int dma_mapping_error(struct device *dev, dma_addr_t dma_addr)
 {
 	debug_dma_mapping_error(dev, dma_addr);
 	if (dma_addr == DMA_MAPPING_ERROR)
-		return 1;
+		return -ENOMEM;
 	return 0;
 }
 
-- 
2.19.1

Re: remove the ->mapping_error method from dma_map_ops V3

[Russell King - ARM Linux]

On Fri, Nov 30, 2018 at 02:22:08PM +0100, Christoph Hellwig wrote:
> 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 direct mappings that have ram at address
> zero and 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.
> 
> A git tree is also available here:
> 
>     git://git.infradead.org/users/hch/misc.git dma-mapping-error.3

Hi Chris,

For patches 1, 3 and 23,

Acked-by: Russell King <rmk+kernel@armlinux.org.uk>

Thanks.

-- 
RMK's Patch system: http://www.armlinux.org.uk/developer/patches/
FTTC broadband for 0.8mile line in suburbia: sync at 12.1Mbps down 622kbps up
According to speedtest.net: 11.9Mbps down 500kbps up

Re: remove the ->mapping_error method from dma_map_ops V3

[Linus Torvalds]

On Fri, Nov 30, 2018 at 5:23 AM Christoph Hellwig <hch@lst.de> wrote:
>
> Error reporting for the dma_map_single and dma_map_page operations is
> currently a mess. [..]

I don't see anything objectionable there, but it's not like I checked
any of the context of the patches. For all I know there are odd corner
cases where some zero vs DMA_MAPPING_ERROR confusion lurks, but I
guess we'll find out..

So you can add my acked-by, fwiw.

                Linus

Re: [PATCH 21/23] xen-swiotlb: remove the mapping_error dma_map_ops method

[Konrad Rzeszutek Wilk]

On Fri, Nov 30, 2018 at 02:22:29PM +0100, Christoph Hellwig wrote:
> Return DMA_MAPPING_ERROR instead of 0 on a dma mapping failure and let
> the core dma-mapping code handle the rest.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>

Reviewed-by: Konrad Rzeszutek Wilk <konrad@darnok.org>
> ---
>  drivers/xen/swiotlb-xen.c | 12 ++----------
>  1 file changed, 2 insertions(+), 10 deletions(-)
> 
> 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,
>  };
> -- 
> 2.19.1
> 

Re: remove the ->mapping_error method from dma_map_ops V3

[Christoph Hellwig]

Does anyone but Linus and Russell have comments on this series?

I'd like to pull it in fairly quickly as I have a fair amount of
work on top of it that I'd like to get into 4.21 as well.

Re: [PATCH 01/23] dma-mapping: provide a generic DMA_MAPPING_ERROR

[Robin Murphy]

On 30/11/2018 13:22, Christoph Hellwig wrote:
> Error handling of the dma_map_single and dma_map_page APIs is a little
> problematic at the moment, in that we use different encodings in the
> returned dma_addr_t to indicate an error.  That means we require an
> additional indirect call to figure out if a dma mapping call returned
> an error, and a lot of boilerplate code to implement these semantics.
> 
> Instead return the maximum addressable value as the error.  As long
> as we don't allow mapping single-byte ranges with single-byte alignment
> this value can never be a valid return.  Additionaly if drivers do
> not check the return value from the dma_map* routines this values means
> they will generally not be pointed to actual memory.
> 
> Once the default value is added here we can start removing the
> various mapping_error methods and just rely on this generic check.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>   include/linux/dma-mapping.h | 6 ++++++
>   1 file changed, 6 insertions(+)
> 
> diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
> index 0f81c713f6e9..46bd612d929e 100644
> --- a/include/linux/dma-mapping.h
> +++ b/include/linux/dma-mapping.h
> @@ -133,6 +133,8 @@ struct dma_map_ops {
>   	u64 (*get_required_mask)(struct device *dev);
>   };
>   
> +#define DMA_MAPPING_ERROR		(~(dma_addr_t)0)
> +
>   extern const struct dma_map_ops dma_direct_ops;
>   extern const struct dma_map_ops dma_virt_ops;
>   
> @@ -576,6 +578,10 @@ 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 (dma_addr == DMA_MAPPING_ERROR)
> +		return 1;
> +
>   	if (ops->mapping_error)
>   		return ops->mapping_error(dev, dma_addr);
>   	return 0;

I'd have been inclined to put the default check here, i.e.

-	return 0
+	return dma_addr == DMA_MAPPING_ERROR

such that the callback retains full precedence and we don't have to deal 
with the non-trivial removals immediately if it comes to it. Not that it 
makes a vast difference though, so either way,

Reviewed-by: Robin Murphy <robin.murphy@arm.com>

Re: [PATCH 01/23] dma-mapping: provide a generic DMA_MAPPING_ERROR

[Christoph Hellwig]

On Tue, Dec 04, 2018 at 04:41:34PM +0000, Robin Murphy wrote:
> I'd have been inclined to put the default check here, i.e.
>
> -	return 0
> +	return dma_addr == DMA_MAPPING_ERROR
>
> such that the callback retains full precedence and we don't have to deal 
> with the non-trivial removals immediately if it comes to it. Not that it 
> makes a vast difference though, so either way,

Ok, I've switched it around.

Re: remove the ->mapping_error method from dma_map_ops V3

[Christoph Hellwig]

I've pulled this into the dma-mapping for-next tree, with the suggestion
from Robin that improves bisectability, and two unused variables found
by the build bot.