[PATCH 26/28] dmapool: add dma_alloc_pages support
Christoph Hellwig
hch at lst.de
Wed Aug 19 02:55:53 EDT 2020
Add an new variant of a dmapool that uses non-coherent memory from
dma_alloc_pages. Unlike the existing mempool_create this one
initialized a pool allocated by the caller to avoid a pointless extra
allocation. At some point it might be worth to also switch the coherent
allocation over to a similar dma_pool_init_coherent helper, but that is
better done as a separate series including a few conversions.
Signed-off-by: Christoph Hellwig <hch at lst.de>
---
include/linux/dmapool.h | 23 ++++-
mm/dmapool.c | 211 +++++++++++++++++++++++++---------------
2 files changed, 154 insertions(+), 80 deletions(-)
diff --git a/include/linux/dmapool.h b/include/linux/dmapool.h
index f632ecfb423840..1387525c4e52e8 100644
--- a/include/linux/dmapool.h
+++ b/include/linux/dmapool.h
@@ -11,6 +11,10 @@
#ifndef LINUX_DMAPOOL_H
#define LINUX_DMAPOOL_H
+#include <linux/dma-direction.h>
+#include <linux/gfp.h>
+#include <linux/spinlock.h>
+#include <linux/list.h>
#include <linux/scatterlist.h>
#include <asm/io.h>
@@ -18,11 +22,28 @@ struct device;
#ifdef CONFIG_HAS_DMA
+struct dma_pool { /* the pool */
+ struct list_head page_list;
+ spinlock_t lock;
+ size_t size;
+ struct device *dev;
+ size_t allocation;
+ size_t boundary;
+ bool is_coherent;
+ enum dma_data_direction dir;
+ char name[32];
+ struct list_head pools;
+};
+
struct dma_pool *dma_pool_create(const char *name, struct device *dev,
size_t size, size_t align, size_t allocation);
-
void dma_pool_destroy(struct dma_pool *pool);
+int dma_pool_init(struct device *dev, struct dma_pool *pool, const char *name,
+ size_t size, size_t align, size_t boundary,
+ enum dma_data_direction dir);
+void dma_pool_exit(struct dma_pool *pool);
+
void *dma_pool_alloc(struct dma_pool *pool, gfp_t mem_flags,
dma_addr_t *handle);
void dma_pool_free(struct dma_pool *pool, void *vaddr, dma_addr_t addr);
diff --git a/mm/dmapool.c b/mm/dmapool.c
index f9fb9bbd733e0f..c60a48b22c8d6a 100644
--- a/mm/dmapool.c
+++ b/mm/dmapool.c
@@ -6,10 +6,10 @@
* Copyright 2007 Intel Corporation
* Author: Matthew Wilcox <willy at linux.intel.com>
*
- * This allocator returns small blocks of a given size which are DMA-able by
- * the given device. It uses the dma_alloc_coherent page allocator to get
- * new pages, then splits them up into blocks of the required size.
- * Many older drivers still have their own code to do this.
+ * This allocator returns small blocks of a given size which are DMA-able by the
+ * given device. It either uses the dma_alloc_coherent or the dma_alloc_pages
+ * allocator to get new pages, then splits them up into blocks of the required
+ * size.
*
* The current design of this allocator is fairly simple. The pool is
* represented by the 'struct dma_pool' which keeps a doubly-linked list of
@@ -39,17 +39,6 @@
#define DMAPOOL_DEBUG 1
#endif
-struct dma_pool { /* the pool */
- struct list_head page_list;
- spinlock_t lock;
- size_t size;
- struct device *dev;
- size_t allocation;
- size_t boundary;
- char name[32];
- struct list_head pools;
-};
-
struct dma_page { /* cacheable header for 'allocation' bytes */
struct list_head page_list;
void *vaddr;
@@ -104,74 +93,40 @@ show_pools(struct device *dev, struct device_attribute *attr, char *buf)
static DEVICE_ATTR(pools, 0444, show_pools, NULL);
-/**
- * dma_pool_create - Creates a pool of consistent memory blocks, for dma.
- * @name: name of pool, for diagnostics
- * @dev: device that will be doing the DMA
- * @size: size of the blocks in this pool.
- * @align: alignment requirement for blocks; must be a power of two
- * @boundary: returned blocks won't cross this power of two boundary
- * Context: not in_interrupt()
- *
- * Given one of these pools, dma_pool_alloc()
- * may be used to allocate memory. Such memory will all have "consistent"
- * DMA mappings, accessible by the device and its driver without using
- * cache flushing primitives. The actual size of blocks allocated may be
- * larger than requested because of alignment.
- *
- * If @boundary is nonzero, objects returned from dma_pool_alloc() won't
- * cross that size boundary. This is useful for devices which have
- * addressing restrictions on individual DMA transfers, such as not crossing
- * boundaries of 4KBytes.
- *
- * Return: a dma allocation pool with the requested characteristics, or
- * %NULL if one can't be created.
- */
-struct dma_pool *dma_pool_create(const char *name, struct device *dev,
- size_t size, size_t align, size_t boundary)
+static int __dma_pool_init(struct device *dev, struct dma_pool *pool,
+ const char *name, size_t size, size_t align, size_t boundary)
{
- struct dma_pool *retval;
size_t allocation;
bool empty = false;
if (align == 0)
align = 1;
- else if (align & (align - 1))
- return NULL;
+ if (align & (align - 1))
+ return -EINVAL;
if (size == 0)
- return NULL;
- else if (size < 4)
- size = 4;
-
- size = ALIGN(size, align);
+ return -EINVAL;
+ size = ALIGN(min_t(size_t, size, 4), align);
allocation = max_t(size_t, size, PAGE_SIZE);
if (!boundary)
boundary = allocation;
- else if ((boundary < size) || (boundary & (boundary - 1)))
- return NULL;
-
- retval = kmalloc_node(sizeof(*retval), GFP_KERNEL, dev_to_node(dev));
- if (!retval)
- return retval;
-
- strlcpy(retval->name, name, sizeof(retval->name));
-
- retval->dev = dev;
-
- INIT_LIST_HEAD(&retval->page_list);
- spin_lock_init(&retval->lock);
- retval->size = size;
- retval->boundary = boundary;
- retval->allocation = allocation;
-
- INIT_LIST_HEAD(&retval->pools);
+ if (boundary < size || (boundary & (boundary - 1)))
+ return -EINVAL;
+
+ strlcpy(pool->name, name, sizeof(pool->name));
+ pool->dev = dev;
+ INIT_LIST_HEAD(&pool->page_list);
+ spin_lock_init(&pool->lock);
+ pool->size = size;
+ pool->boundary = boundary;
+ pool->allocation = allocation;
+ INIT_LIST_HEAD(&pool->pools);
/*
* pools_lock ensures that the ->dma_pools list does not get corrupted.
* pools_reg_lock ensures that there is not a race between
- * dma_pool_create() and dma_pool_destroy() or within dma_pool_create()
+ * __dma_pool_init() and dma_pool_exit() or within dma_pool_create()
* when the first invocation of dma_pool_create() failed on
* device_create_file() and the second assumes that it has been done (I
* know it is a short window).
@@ -180,7 +135,7 @@ struct dma_pool *dma_pool_create(const char *name, struct device *dev,
mutex_lock(&pools_lock);
if (list_empty(&dev->dma_pools))
empty = true;
- list_add(&retval->pools, &dev->dma_pools);
+ list_add(&pool->pools, &dev->dma_pools);
mutex_unlock(&pools_lock);
if (empty) {
int err;
@@ -188,18 +143,94 @@ struct dma_pool *dma_pool_create(const char *name, struct device *dev,
err = device_create_file(dev, &dev_attr_pools);
if (err) {
mutex_lock(&pools_lock);
- list_del(&retval->pools);
+ list_del(&pool->pools);
mutex_unlock(&pools_lock);
mutex_unlock(&pools_reg_lock);
- kfree(retval);
- return NULL;
+ return err;
}
}
mutex_unlock(&pools_reg_lock);
- return retval;
+ return 0;
+}
+
+/**
+ * dma_pool_create - Creates a pool of consistent memory blocks, for dma.
+ * @name: name of pool, for diagnostics
+ * @dev: device that will be doing the DMA
+ * @size: size of the blocks in this pool.
+ * @align: alignment requirement for blocks; must be a power of two
+ * @boundary: returned blocks won't cross this power of two boundary
+ * Context: not in_interrupt()
+ *
+ * Given one of these pools, dma_pool_alloc()
+ * may be used to allocate memory. Such memory will all have "consistent"
+ * DMA mappings, accessible by the device and its driver without using
+ * cache flushing primitives. The actual size of blocks allocated may be
+ * larger than requested because of alignment.
+ *
+ * If @boundary is nonzero, objects returned from dma_pool_alloc() won't
+ * cross that size boundary. This is useful for devices which have
+ * addressing restrictions on individual DMA transfers, such as not crossing
+ * boundaries of 4KBytes.
+ * Return: a dma allocation pool with the requested characteristics, or
+ * %NULL if one can't be created.
+ */
+struct dma_pool *dma_pool_create(const char *name, struct device *dev,
+ size_t size, size_t align, size_t boundary)
+{
+ struct dma_pool *pool;
+
+ pool = kmalloc_node(sizeof(*pool), GFP_KERNEL, dev_to_node(dev));
+ if (!pool)
+ return NULL;
+ if (__dma_pool_init(dev, pool, name, size, align, boundary))
+ goto out_free_pool;
+ pool->is_coherent = true;
+ return pool;
+out_free_pool:
+ kfree(pool);
+ return NULL;
}
EXPORT_SYMBOL(dma_pool_create);
+/**
+ * dma_pool_init - initialize a pool DMA addressable memory
+ * @dev: device that will be doing the DMA
+ * @pool: pool to initialize
+ * @name: name of pool, for diagnostics
+ * @size: size of the blocks in this pool.
+ * @align: alignment requirement for blocks; must be a power of two
+ * @boundary: returned blocks won't cross this power of two boundary
+ * @dir: DMA direction the allocations are going to be used for
+ *
+ * Context: not in_interrupt()
+ *
+ * Given one of these pools, dma_pool_alloc() may be used to allocate memory.
+ * Such memory will have the same semantics as memory returned from
+ * dma_alloc_pages(), that is ownership needs to be transferred to and from the
+ * device. The actual size of blocks allocated may be larger than requested
+ * because of alignment.
+ *
+ * If @boundary is nonzero, objects returned from dma_pool_alloc() won't
+ * cross that size boundary. This is useful for devices which have
+ * addressing restrictions on individual DMA transfers, such as not crossing
+ * boundaries of 4KBytes.
+ */
+int dma_pool_init(struct device *dev, struct dma_pool *pool, const char *name,
+ size_t size, size_t align, size_t boundary,
+ enum dma_data_direction dir)
+{
+ int ret;
+
+ ret = __dma_pool_init(dev, pool, name, size, align, boundary);
+ if (ret)
+ return ret;
+ pool->is_coherent = false;
+ pool->dir = dir;
+ return 0;
+}
+EXPORT_SYMBOL(dma_pool_init);
+
static void pool_initialise_page(struct dma_pool *pool, struct dma_page *page)
{
unsigned int offset = 0;
@@ -223,8 +254,12 @@ static struct dma_page *pool_alloc_page(struct dma_pool *pool, gfp_t mem_flags)
page = kmalloc(sizeof(*page), mem_flags);
if (!page)
return NULL;
- page->vaddr = dma_alloc_coherent(pool->dev, pool->allocation,
- &page->dma, mem_flags);
+ if (pool->is_coherent)
+ page->vaddr = dma_alloc_coherent(pool->dev, pool->allocation,
+ &page->dma, mem_flags);
+ else
+ page->vaddr = dma_alloc_pages(pool->dev, pool->allocation,
+ &page->dma, pool->dir, mem_flags);
if (page->vaddr) {
#ifdef DMAPOOL_DEBUG
memset(page->vaddr, POOL_POISON_FREED, pool->allocation);
@@ -251,20 +286,25 @@ static void pool_free_page(struct dma_pool *pool, struct dma_page *page)
#ifdef DMAPOOL_DEBUG
memset(page->vaddr, POOL_POISON_FREED, pool->allocation);
#endif
- dma_free_coherent(pool->dev, pool->allocation, page->vaddr, dma);
+ if (pool->is_coherent)
+ dma_free_coherent(pool->dev, pool->allocation, page->vaddr,
+ dma);
+ else
+ dma_free_pages(pool->dev, pool->allocation, page->vaddr, dma,
+ pool->dir);
list_del(&page->page_list);
kfree(page);
}
/**
- * dma_pool_destroy - destroys a pool of dma memory blocks.
+ * dma_pool_exit - destroys a pool of dma memory blocks.
* @pool: dma pool that will be destroyed
* Context: !in_interrupt()
*
- * Caller guarantees that no more memory from the pool is in use,
- * and that nothing will try to use the pool after this call.
+ * Caller guarantees that no more memory from the pool is in use, and that
+ * nothing will try to use the pool after this call.
*/
-void dma_pool_destroy(struct dma_pool *pool)
+void dma_pool_exit(struct dma_pool *pool)
{
bool empty = false;
@@ -299,7 +339,20 @@ void dma_pool_destroy(struct dma_pool *pool)
} else
pool_free_page(pool, page);
}
+}
+EXPORT_SYMBOL(dma_pool_exit);
+/**
+ * dma_pool_destroy - destroys a pool of dma memory blocks.
+ * @pool: dma pool that will be destroyed
+ * Context: !in_interrupt()
+ *
+ * Caller guarantees that no more memory from the pool is in use,
+ * and that nothing will try to use the pool after this call.
+ */
+void dma_pool_destroy(struct dma_pool *pool)
+{
+ dma_pool_exit(pool);
kfree(pool);
}
EXPORT_SYMBOL(dma_pool_destroy);
--
2.28.0
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