[PATCH v4 01/44] dma-mapping: Use unsigned long for dma_attrs

From: Krzysztof Kozlowski
Date: Fri Jun 10 2016 - 06:27:56 EST

The dma-mapping core and the implementations do not change the
DMA attributes passed by pointer. Thus the pointer can point to const
data. However the attributes do not have to be a bitfield. Instead
unsigned long will do fine:

1. This is just simpler. Both in terms of reading the code and setting
attributes. Instead of initializing local attributes on the stack
and passing pointer to it to dma_set_attr(), just set the bits.

2. It brings safeness and checking for const correctness because the
attributes are passed by value.

Semantic patches for this change (at least most of them):
===
virtual patch
virtual context

@r@
identifier f, attrs;

@@
f(...,
- struct dma_attrs *attrs
+ unsigned long attrs
, ...)
{
...
}

@@
identifier r.f;
@@
f(...,
- NULL
+ 0
)
===
// Options: --all-includes
virtual patch
virtual context

@r@
identifier f, attrs;
type t;

@@
t f(..., struct dma_attrs *attrs);

@@
identifier r.f;
@@
f(...,
- NULL
+ 0
)
===

Signed-off-by: Krzysztof Kozlowski <k.kozlowski@xxxxxxxxxxx>
---
Documentation/DMA-API.txt | 29 +++++------
Documentation/DMA-attributes.txt | 2 +-
include/linux/dma-attrs.h | 72 ---------------------------
include/linux/dma-mapping.h | 105 +++++++++++++++++++++++----------------
lib/dma-noop.c | 9 ++--
5 files changed, 80 insertions(+), 137 deletions(-)
delete mode 100644 include/linux/dma-attrs.h

diff --git a/Documentation/DMA-API.txt b/Documentation/DMA-API.txt
index 45ef3f279c3b..24f9688bb98a 100644
--- a/Documentation/DMA-API.txt
+++ b/Documentation/DMA-API.txt
@@ -369,35 +369,32 @@ See also dma_map_single().
dma_addr_t
dma_map_single_attrs(struct device *dev, void *cpu_addr, size_t size,
enum dma_data_direction dir,
- struct dma_attrs *attrs)
+ unsigned long attrs)

void
dma_unmap_single_attrs(struct device *dev, dma_addr_t dma_addr,
size_t size, enum dma_data_direction dir,
- struct dma_attrs *attrs)
+ unsigned long attrs)

int
dma_map_sg_attrs(struct device *dev, struct scatterlist *sgl,
int nents, enum dma_data_direction dir,
- struct dma_attrs *attrs)
+ unsigned long attrs)

void
dma_unmap_sg_attrs(struct device *dev, struct scatterlist *sgl,
int nents, enum dma_data_direction dir,
- struct dma_attrs *attrs)
+ unsigned long attrs)

The four functions above are just like the counterpart functions
without the _attrs suffixes, except that they pass an optional
-struct dma_attrs*.
-
-struct dma_attrs encapsulates a set of "DMA attributes". For the
-definition of struct dma_attrs see linux/dma-attrs.h.
+dma_attrs.

The interpretation of DMA attributes is architecture-specific, and
each attribute should be documented in Documentation/DMA-attributes.txt.

-If struct dma_attrs* is NULL, the semantics of each of these
-functions is identical to those of the corresponding function
+If dma_attrs are 0, the semantics of each of these functions
+is identical to those of the corresponding function
without the _attrs suffix. As a result dma_map_single_attrs()
can generally replace dma_map_single(), etc.

@@ -405,15 +402,15 @@ As an example of the use of the *_attrs functions, here's how
you could pass an attribute DMA_ATTR_FOO when mapping memory
for DMA:

-#include <linux/dma-attrs.h>
-/* DMA_ATTR_FOO should be defined in linux/dma-attrs.h and
+#include <linux/dma-mapping.h>
+/* DMA_ATTR_FOO should be defined in linux/dma-mapping.h and
* documented in Documentation/DMA-attributes.txt */
...

- DEFINE_DMA_ATTRS(attrs);
- dma_set_attr(DMA_ATTR_FOO, &attrs);
+ unsigned long attr;
+ attr |= DMA_ATTR_FOO;
....
- n = dma_map_sg_attrs(dev, sg, nents, DMA_TO_DEVICE, &attr);
+ n = dma_map_sg_attrs(dev, sg, nents, DMA_TO_DEVICE, attr);
....

Architectures that care about DMA_ATTR_FOO would check for its
@@ -422,7 +419,7 @@ routines, e.g.:

void whizco_dma_map_sg_attrs(struct device *dev, dma_addr_t dma_addr,
size_t size, enum dma_data_direction dir,
- struct dma_attrs *attrs)
+ unsigned long attrs)
{
....
int foo = dma_get_attr(DMA_ATTR_FOO, attrs);
diff --git a/Documentation/DMA-attributes.txt b/Documentation/DMA-attributes.txt
index e8cf9cf873b3..2d455a5cf671 100644
--- a/Documentation/DMA-attributes.txt
+++ b/Documentation/DMA-attributes.txt
@@ -2,7 +2,7 @@
==============

This document describes the semantics of the DMA attributes that are
-defined in linux/dma-attrs.h.
+defined in linux/dma-mapping.h.

DMA_ATTR_WRITE_BARRIER
----------------------
diff --git a/include/linux/dma-attrs.h b/include/linux/dma-attrs.h
deleted file mode 100644
index f3c5aeadb100..000000000000
--- a/include/linux/dma-attrs.h
+++ /dev/null
@@ -1,72 +0,0 @@
-#ifndef _DMA_ATTR_H
-#define _DMA_ATTR_H
-
-#include <linux/bitmap.h>
-#include <linux/bitops.h>
-#include <linux/bug.h>
-
-/**
- * an enum dma_attr represents an attribute associated with a DMA
- * mapping. The semantics of each attribute should be defined in
- * Documentation/DMA-attributes.txt.
- */
-enum dma_attr {
- DMA_ATTR_WRITE_BARRIER,
- DMA_ATTR_WEAK_ORDERING,
- DMA_ATTR_WRITE_COMBINE,
- DMA_ATTR_NON_CONSISTENT,
- DMA_ATTR_NO_KERNEL_MAPPING,
- DMA_ATTR_SKIP_CPU_SYNC,
- DMA_ATTR_FORCE_CONTIGUOUS,
- DMA_ATTR_ALLOC_SINGLE_PAGES,
- DMA_ATTR_MAX,
-};
-
-#define __DMA_ATTRS_LONGS BITS_TO_LONGS(DMA_ATTR_MAX)
-
-/**
- * struct dma_attrs - an opaque container for DMA attributes
- * @flags - bitmask representing a collection of enum dma_attr
- */
-struct dma_attrs {
- unsigned long flags[__DMA_ATTRS_LONGS];
-};
-
-#define DEFINE_DMA_ATTRS(x) \
- struct dma_attrs x = { \
- .flags = { [0 ... __DMA_ATTRS_LONGS-1] = 0 }, \
- }
-
-static inline void init_dma_attrs(struct dma_attrs *attrs)
-{
- bitmap_zero(attrs->flags, __DMA_ATTRS_LONGS);
-}
-
-/**
- * dma_set_attr - set a specific attribute
- * @attr: attribute to set
- * @attrs: struct dma_attrs (may be NULL)
- */
-static inline void dma_set_attr(enum dma_attr attr, struct dma_attrs *attrs)
-{
- if (attrs == NULL)
- return;
- BUG_ON(attr >= DMA_ATTR_MAX);
- __set_bit(attr, attrs->flags);
-}
-
-/**
- * dma_get_attr - check for a specific attribute
- * @attr: attribute to set
- * @attrs: struct dma_attrs (may be NULL)
- */
-static inline int dma_get_attr(enum dma_attr attr,
- const struct dma_attrs *attrs)
-{
- if (attrs == NULL)
- return 0;
- BUG_ON(attr >= DMA_ATTR_MAX);
- return test_bit(attr, attrs->flags);
-}
-
-#endif /* _DMA_ATTR_H */
diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
index 71c1b215ef66..1fd9860487b1 100644
--- a/include/linux/dma-mapping.h
+++ b/include/linux/dma-mapping.h
@@ -5,13 +5,25 @@
#include <linux/string.h>
#include <linux/device.h>
#include <linux/err.h>
-#include <linux/dma-attrs.h>
#include <linux/dma-debug.h>
#include <linux/dma-direction.h>
#include <linux/scatterlist.h>
#include <linux/kmemcheck.h>
#include <linux/bug.h>

+/**
+ * List of possible attributes associated with a DMA mapping. The semantics
+ * of each attribute should be defined in Documentation/DMA-attributes.txt.
+ */
+#define DMA_ATTR_WRITE_BARRIER (1UL << 0)
+#define DMA_ATTR_WEAK_ORDERING (1UL << 1)
+#define DMA_ATTR_WRITE_COMBINE (1UL << 2)
+#define DMA_ATTR_NON_CONSISTENT (1UL << 3)
+#define DMA_ATTR_NO_KERNEL_MAPPING (1UL << 4)
+#define DMA_ATTR_SKIP_CPU_SYNC (1UL << 5)
+#define DMA_ATTR_FORCE_CONTIGUOUS (1UL << 6)
+#define DMA_ATTR_ALLOC_SINGLE_PAGES (1UL << 7)
+
/*
* A dma_addr_t can hold any valid DMA or bus address for the platform.
* It can be given to a device to use as a DMA source or target. A CPU cannot
@@ -21,34 +33,35 @@
struct dma_map_ops {
void* (*alloc)(struct device *dev, size_t size,
dma_addr_t *dma_handle, gfp_t gfp,
- struct dma_attrs *attrs);
+ unsigned long attrs);
void (*free)(struct device *dev, size_t size,
void *vaddr, dma_addr_t dma_handle,
- struct dma_attrs *attrs);
+ unsigned long attrs);
int (*mmap)(struct device *, struct vm_area_struct *,
- void *, dma_addr_t, size_t, struct dma_attrs *attrs);
+ void *, dma_addr_t, size_t,
+ unsigned long attrs);

int (*get_sgtable)(struct device *dev, struct sg_table *sgt, void *,
- dma_addr_t, size_t, struct dma_attrs *attrs);
+ dma_addr_t, size_t, unsigned long attrs);

dma_addr_t (*map_page)(struct device *dev, struct page *page,
unsigned long offset, size_t size,
enum dma_data_direction dir,
- struct dma_attrs *attrs);
+ unsigned long attrs);
void (*unmap_page)(struct device *dev, dma_addr_t dma_handle,
size_t size, enum dma_data_direction dir,
- struct dma_attrs *attrs);
+ unsigned long attrs);
/*
* map_sg returns 0 on error and a value > 0 on success.
* It should never return a value < 0.
*/
int (*map_sg)(struct device *dev, struct scatterlist *sg,
int nents, enum dma_data_direction dir,
- struct dma_attrs *attrs);
+ unsigned long attrs);
void (*unmap_sg)(struct device *dev,
struct scatterlist *sg, int nents,
enum dma_data_direction dir,
- struct dma_attrs *attrs);
+ unsigned long attrs);
void (*sync_single_for_cpu)(struct device *dev,
dma_addr_t dma_handle, size_t size,
enum dma_data_direction dir);
@@ -88,6 +101,16 @@ static inline int is_device_dma_capable(struct device *dev)
return dev->dma_mask != NULL && *dev->dma_mask != DMA_MASK_NONE;
}

+/**
+ * dma_get_attr - check for a specific attribute
+ * @attr: attribute to look for
+ * @attrs: attributes to check within
+ */
+static inline bool dma_get_attr(unsigned long attr, unsigned long attrs)
+{
+ return !!(attr & attrs);
+}
+
#ifdef CONFIG_HAVE_GENERIC_DMA_COHERENT
/*
* These three functions are only for dma allocator.
@@ -123,7 +146,7 @@ static inline struct dma_map_ops *get_dma_ops(struct device *dev)
static inline dma_addr_t dma_map_single_attrs(struct device *dev, void *ptr,
size_t size,
enum dma_data_direction dir,
- struct dma_attrs *attrs)
+ unsigned long attrs)
{
struct dma_map_ops *ops = get_dma_ops(dev);
dma_addr_t addr;
@@ -142,7 +165,7 @@ static inline dma_addr_t dma_map_single_attrs(struct device *dev, void *ptr,
static inline void dma_unmap_single_attrs(struct device *dev, dma_addr_t addr,
size_t size,
enum dma_data_direction dir,
- struct dma_attrs *attrs)
+ unsigned long attrs)
{
struct dma_map_ops *ops = get_dma_ops(dev);

@@ -158,7 +181,7 @@ static inline void dma_unmap_single_attrs(struct device *dev, dma_addr_t addr,
*/
static inline int dma_map_sg_attrs(struct device *dev, struct scatterlist *sg,
int nents, enum dma_data_direction dir,
- struct dma_attrs *attrs)
+ unsigned long attrs)
{
struct dma_map_ops *ops = get_dma_ops(dev);
int i, ents;
@@ -176,7 +199,7 @@ static inline int dma_map_sg_attrs(struct device *dev, struct scatterlist *sg,

static inline void dma_unmap_sg_attrs(struct device *dev, struct scatterlist *sg,
int nents, enum dma_data_direction dir,
- struct dma_attrs *attrs)
+ unsigned long attrs)
{
struct dma_map_ops *ops = get_dma_ops(dev);

@@ -195,7 +218,7 @@ static inline dma_addr_t dma_map_page(struct device *dev, struct page *page,

kmemcheck_mark_initialized(page_address(page) + offset, size);
BUG_ON(!valid_dma_direction(dir));
- addr = ops->map_page(dev, page, offset, size, dir, NULL);
+ addr = ops->map_page(dev, page, offset, size, dir, 0);
debug_dma_map_page(dev, page, offset, size, dir, addr, false);

return addr;
@@ -208,7 +231,7 @@ static inline void dma_unmap_page(struct device *dev, dma_addr_t addr,

BUG_ON(!valid_dma_direction(dir));
if (ops->unmap_page)
- ops->unmap_page(dev, addr, size, dir, NULL);
+ ops->unmap_page(dev, addr, size, dir, 0);
debug_dma_unmap_page(dev, addr, size, dir, false);
}

@@ -289,10 +312,10 @@ 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, NULL)
-#define dma_unmap_single(d, a, s, r) dma_unmap_single_attrs(d, a, s, r, NULL)
-#define dma_map_sg(d, s, n, r) dma_map_sg_attrs(d, s, n, r, NULL)
-#define dma_unmap_sg(d, s, n, r) dma_unmap_sg_attrs(d, s, n, r, NULL)
+#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)

extern int dma_common_mmap(struct device *dev, struct vm_area_struct *vma,
void *cpu_addr, dma_addr_t dma_addr, size_t size);
@@ -321,7 +344,7 @@ void dma_common_free_remap(void *cpu_addr, size_t size, unsigned long vm_flags);
*/
static inline int
dma_mmap_attrs(struct device *dev, struct vm_area_struct *vma, void *cpu_addr,
- dma_addr_t dma_addr, size_t size, struct dma_attrs *attrs)
+ dma_addr_t dma_addr, size_t size, unsigned long attrs)
{
struct dma_map_ops *ops = get_dma_ops(dev);
BUG_ON(!ops);
@@ -330,7 +353,7 @@ dma_mmap_attrs(struct device *dev, struct vm_area_struct *vma, void *cpu_addr,
return dma_common_mmap(dev, vma, cpu_addr, dma_addr, size);
}

-#define dma_mmap_coherent(d, v, c, h, s) dma_mmap_attrs(d, v, c, h, s, NULL)
+#define dma_mmap_coherent(d, v, c, h, s) dma_mmap_attrs(d, v, c, h, s, 0)

int
dma_common_get_sgtable(struct device *dev, struct sg_table *sgt,
@@ -338,7 +361,8 @@ dma_common_get_sgtable(struct device *dev, struct sg_table *sgt,

static inline int
dma_get_sgtable_attrs(struct device *dev, struct sg_table *sgt, void *cpu_addr,
- dma_addr_t dma_addr, size_t size, struct dma_attrs *attrs)
+ dma_addr_t dma_addr, size_t size,
+ unsigned long attrs)
{
struct dma_map_ops *ops = get_dma_ops(dev);
BUG_ON(!ops);
@@ -348,7 +372,7 @@ dma_get_sgtable_attrs(struct device *dev, struct sg_table *sgt, void *cpu_addr,
return dma_common_get_sgtable(dev, sgt, cpu_addr, dma_addr, size);
}

-#define dma_get_sgtable(d, t, v, h, s) dma_get_sgtable_attrs(d, t, v, h, s, NULL)
+#define dma_get_sgtable(d, t, v, h, s) dma_get_sgtable_attrs(d, t, v, h, s, 0)

#ifndef arch_dma_alloc_attrs
#define arch_dma_alloc_attrs(dev, flag) (true)
@@ -356,7 +380,7 @@ dma_get_sgtable_attrs(struct device *dev, struct sg_table *sgt, void *cpu_addr,

static inline void *dma_alloc_attrs(struct device *dev, size_t size,
dma_addr_t *dma_handle, gfp_t flag,
- struct dma_attrs *attrs)
+ unsigned long attrs)
{
struct dma_map_ops *ops = get_dma_ops(dev);
void *cpu_addr;
@@ -378,7 +402,7 @@ static inline void *dma_alloc_attrs(struct device *dev, size_t size,

static inline void dma_free_attrs(struct device *dev, size_t size,
void *cpu_addr, dma_addr_t dma_handle,
- struct dma_attrs *attrs)
+ unsigned long attrs)
{
struct dma_map_ops *ops = get_dma_ops(dev);

@@ -398,31 +422,27 @@ static inline void dma_free_attrs(struct device *dev, size_t size,
static inline void *dma_alloc_coherent(struct device *dev, size_t size,
dma_addr_t *dma_handle, gfp_t flag)
{
- return dma_alloc_attrs(dev, size, dma_handle, flag, NULL);
+ return dma_alloc_attrs(dev, size, dma_handle, flag, 0);
}

static inline void dma_free_coherent(struct device *dev, size_t size,
void *cpu_addr, dma_addr_t dma_handle)
{
- return dma_free_attrs(dev, size, cpu_addr, dma_handle, NULL);
+ return dma_free_attrs(dev, size, cpu_addr, dma_handle, 0);
}

static inline void *dma_alloc_noncoherent(struct device *dev, size_t size,
dma_addr_t *dma_handle, gfp_t gfp)
{
- DEFINE_DMA_ATTRS(attrs);
-
- dma_set_attr(DMA_ATTR_NON_CONSISTENT, &attrs);
- return dma_alloc_attrs(dev, size, dma_handle, gfp, &attrs);
+ return dma_alloc_attrs(dev, size, dma_handle, gfp,
+ DMA_ATTR_NON_CONSISTENT);
}

static inline void dma_free_noncoherent(struct device *dev, size_t size,
void *cpu_addr, dma_addr_t dma_handle)
{
- DEFINE_DMA_ATTRS(attrs);
-
- dma_set_attr(DMA_ATTR_NON_CONSISTENT, &attrs);
- dma_free_attrs(dev, size, cpu_addr, dma_handle, &attrs);
+ dma_free_attrs(dev, size, cpu_addr, dma_handle,
+ DMA_ATTR_NON_CONSISTENT);
}

static inline int dma_mapping_error(struct device *dev, dma_addr_t dma_addr)
@@ -646,9 +666,8 @@ static inline void dmam_release_declared_memory(struct device *dev)
static inline void *dma_alloc_wc(struct device *dev, size_t size,
dma_addr_t *dma_addr, gfp_t gfp)
{
- DEFINE_DMA_ATTRS(attrs);
- dma_set_attr(DMA_ATTR_WRITE_COMBINE, &attrs);
- return dma_alloc_attrs(dev, size, dma_addr, gfp, &attrs);
+ return dma_alloc_attrs(dev, size, dma_addr, gfp,
+ DMA_ATTR_WRITE_COMBINE);
}
#ifndef dma_alloc_writecombine
#define dma_alloc_writecombine dma_alloc_wc
@@ -657,9 +676,8 @@ static inline void *dma_alloc_wc(struct device *dev, size_t size,
static inline void dma_free_wc(struct device *dev, size_t size,
void *cpu_addr, dma_addr_t dma_addr)
{
- DEFINE_DMA_ATTRS(attrs);
- dma_set_attr(DMA_ATTR_WRITE_COMBINE, &attrs);
- return dma_free_attrs(dev, size, cpu_addr, dma_addr, &attrs);
+ return dma_free_attrs(dev, size, cpu_addr, dma_addr,
+ DMA_ATTR_WRITE_COMBINE);
}
#ifndef dma_free_writecombine
#define dma_free_writecombine dma_free_wc
@@ -670,9 +688,8 @@ static inline int dma_mmap_wc(struct device *dev,
void *cpu_addr, dma_addr_t dma_addr,
size_t size)
{
- DEFINE_DMA_ATTRS(attrs);
- dma_set_attr(DMA_ATTR_WRITE_COMBINE, &attrs);
- return dma_mmap_attrs(dev, vma, cpu_addr, dma_addr, size, &attrs);
+ return dma_mmap_attrs(dev, vma, cpu_addr, dma_addr, size,
+ DMA_ATTR_WRITE_COMBINE);
}
#ifndef dma_mmap_writecombine
#define dma_mmap_writecombine dma_mmap_wc
diff --git a/lib/dma-noop.c b/lib/dma-noop.c
index 72145646857e..3d766e78fbe2 100644
--- a/lib/dma-noop.c
+++ b/lib/dma-noop.c
@@ -10,7 +10,7 @@

static void *dma_noop_alloc(struct device *dev, size_t size,
dma_addr_t *dma_handle, gfp_t gfp,
- struct dma_attrs *attrs)
+ unsigned long attrs)
{
void *ret;

@@ -22,7 +22,7 @@ static void *dma_noop_alloc(struct device *dev, size_t size,

static void dma_noop_free(struct device *dev, size_t size,
void *cpu_addr, dma_addr_t dma_addr,
- struct dma_attrs *attrs)
+ unsigned long attrs)
{
free_pages((unsigned long)cpu_addr, get_order(size));
}
@@ -30,13 +30,14 @@ static void dma_noop_free(struct device *dev, size_t size,
static dma_addr_t dma_noop_map_page(struct device *dev, struct page *page,
unsigned long offset, size_t size,
enum dma_data_direction dir,
- struct dma_attrs *attrs)
+ unsigned long attrs)
{
return page_to_phys(page) + offset;
}

static int dma_noop_map_sg(struct device *dev, struct scatterlist *sgl, int nents,
- enum dma_data_direction dir, struct dma_attrs *attrs)
+ enum dma_data_direction dir,
+ unsigned long attrs)
{
int i;
struct scatterlist *sg;
--
1.9.1