Merge branch 'dmapool' of git://git.kernel.org/pub/scm/linux/kernel/git/willy/misc

* 'dmapool' of git://git.kernel.org/pub/scm/linux/kernel/git/willy/misc:
  pool: Improve memory usage for devices which can't cross boundaries
  Change dmapool free block management
  dmapool: Tidy up includes and add comments
  dmapool: Validate parameters to dma_pool_create
  Avoid taking waitqueue lock in dmapool
  dmapool: Fix style problems
  Move dmapool.c to mm/ directory

2 files changed, 501 insertions, 0 deletions

diff --git a/mm/Makefile b/mm/Makefile
index 44e2528af70c..4af5dff37277 100644
--- a/mm/Makefile
+++ b/mm/Makefile
@@ -16,6 +16,7 @@ obj-y			:= bootmem.o filemap.o mempool.o oom_kill.o fadvise.o \
 obj-$(CONFIG_PROC_PAGE_MONITOR) += pagewalk.o
 obj-$(CONFIG_BOUNCE)    += bounce.o
 obj-$(CONFIG_SWAP)      += page_io.o swap_state.o swapfile.o thrash.o
+obj-$(CONFIG_HAS_DMA)   += dmapool.o
 obj-$(CONFIG_HUGETLBFS) += hugetlb.o
 obj-$(CONFIG_NUMA)      += mempolicy.o
 obj-$(CONFIG_SPARSEMEM) += sparse.o
diff --git a/mm/dmapool.c b/mm/dmapool.c
new file mode 100644
index 000000000000..34aaac451a96
--- /dev/null
+++ b/mm/dmapool.c
@@ -0,0 +1,500 @@
+/*
+ * DMA Pool allocator
+ *
+ * Copyright 2001 David Brownell
+ * Copyright 2007 Intel Corporation
+ *   Author: Matthew Wilcox <willy@linux.intel.com>
+ *
+ * This software may be redistributed and/or modified under the terms of
+ * the GNU General Public License ("GPL") version 2 as published by the
+ * Free Software Foundation.
+ *
+ * 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.
+ *
+ * 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
+ * allocated pages.  Each page in the page_list is split into blocks of at
+ * least 'size' bytes.  Free blocks are tracked in an unsorted singly-linked
+ * list of free blocks within the page.  Used blocks aren't tracked, but we
+ * keep a count of how many are currently allocated from each page.
+ */
+
+#include <linux/device.h>
+#include <linux/dma-mapping.h>
+#include <linux/dmapool.h>
+#include <linux/kernel.h>
+#include <linux/list.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/poison.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/string.h>
+#include <linux/types.h>
+#include <linux/wait.h>
+
+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];
+        wait_queue_head_t waitq;
+        struct list_head pools;
+};
+
+struct dma_page {               /* cacheable header for 'allocation' bytes */
+        struct list_head page_list;
+        void *vaddr;
+        dma_addr_t dma;
+        unsigned int in_use;
+        unsigned int offset;
+};
+
+#define POOL_TIMEOUT_JIFFIES    ((100 /* msec */ * HZ) / 1000)
+
+static DEFINE_MUTEX(pools_lock);
+
+static ssize_t
+show_pools(struct device *dev, struct device_attribute *attr, char *buf)
+{
+        unsigned temp;
+        unsigned size;
+        char *next;
+        struct dma_page *page;
+        struct dma_pool *pool;
+
+        next = buf;
+        size = PAGE_SIZE;
+
+        temp = scnprintf(next, size, "poolinfo - 0.1\n");
+        size -= temp;
+        next += temp;
+
+        mutex_lock(&pools_lock);
+        list_for_each_entry(pool, &dev->dma_pools, pools) {
+                unsigned pages = 0;
+                unsigned blocks = 0;
+
+                list_for_each_entry(page, &pool->page_list, page_list) {
+                        pages++;
+                        blocks += page->in_use;
+                }
+
+                /* per-pool info, no real statistics yet */
+                temp = scnprintf(next, size, "%-16s %4u %4Zu %4Zu %2u\n",
+                                 pool->name, blocks,
+                                 pages * (pool->allocation / pool->size),
+                                 pool->size, pages);
+                size -= temp;
+                next += temp;
+        }
+        mutex_unlock(&pools_lock);
+
+        return PAGE_SIZE - size;
+}
+
+static DEVICE_ATTR(pools, S_IRUGO, 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: !in_interrupt()
+ *
+ * Returns a dma allocation pool with the requested characteristics, or
+ * null if one can't be created.  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.
+ */
+struct dma_pool *dma_pool_create(const char *name, struct device *dev,
+                                 size_t size, size_t align, size_t boundary)
+{
+        struct dma_pool *retval;
+        size_t allocation;
+
+        if (align == 0) {
+                align = 1;
+        } else if (align & (align - 1)) {
+                return NULL;
+        }
+
+        if (size == 0) {
+                return NULL;
+        } else if (size < 4) {
+                size = 4;
+        }
+
+        if ((size % align) != 0)
+                size = ALIGN(size, 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_waitqueue_head(&retval->waitq);
+
+        if (dev) {
+                int ret;
+
+                mutex_lock(&pools_lock);
+                if (list_empty(&dev->dma_pools))
+                        ret = device_create_file(dev, &dev_attr_pools);
+                else
+                        ret = 0;
+                /* note:  not currently insisting "name" be unique */
+                if (!ret)
+                        list_add(&retval->pools, &dev->dma_pools);
+                else {
+                        kfree(retval);
+                        retval = NULL;
+                }
+                mutex_unlock(&pools_lock);
+        } else
+                INIT_LIST_HEAD(&retval->pools);
+
+        return retval;
+}
+EXPORT_SYMBOL(dma_pool_create);
+
+static void pool_initialise_page(struct dma_pool *pool, struct dma_page *page)
+{
+        unsigned int offset = 0;
+        unsigned int next_boundary = pool->boundary;
+
+        do {
+                unsigned int next = offset + pool->size;
+                if (unlikely((next + pool->size) >= next_boundary)) {
+                        next = next_boundary;
+                        next_boundary += pool->boundary;
+                }
+                *(int *)(page->vaddr + offset) = next;
+                offset = next;
+        } while (offset < pool->allocation);
+}
+
+static struct dma_page *pool_alloc_page(struct dma_pool *pool, gfp_t mem_flags)
+{
+        struct dma_page *page;
+
+        page = kmalloc(sizeof(*page), mem_flags);
+        if (!page)
+                return NULL;
+        page->vaddr = dma_alloc_coherent(pool->dev, pool->allocation,
+                                         &page->dma, mem_flags);
+        if (page->vaddr) {
+#ifdef  CONFIG_DEBUG_SLAB
+                memset(page->vaddr, POOL_POISON_FREED, pool->allocation);
+#endif
+                pool_initialise_page(pool, page);
+                list_add(&page->page_list, &pool->page_list);
+                page->in_use = 0;
+                page->offset = 0;
+        } else {
+                kfree(page);
+                page = NULL;
+        }
+        return page;
+}
+
+static inline int is_page_busy(struct dma_page *page)
+{
+        return page->in_use != 0;
+}
+
+static void pool_free_page(struct dma_pool *pool, struct dma_page *page)
+{
+        dma_addr_t dma = page->dma;
+
+#ifdef  CONFIG_DEBUG_SLAB
+        memset(page->vaddr, POOL_POISON_FREED, pool->allocation);
+#endif
+        dma_free_coherent(pool->dev, pool->allocation, page->vaddr, dma);
+        list_del(&page->page_list);
+        kfree(page);
+}
+
+/**
+ * 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)
+{
+        mutex_lock(&pools_lock);
+        list_del(&pool->pools);
+        if (pool->dev && list_empty(&pool->dev->dma_pools))
+                device_remove_file(pool->dev, &dev_attr_pools);
+        mutex_unlock(&pools_lock);
+
+        while (!list_empty(&pool->page_list)) {
+                struct dma_page *page;
+                page = list_entry(pool->page_list.next,
+                                  struct dma_page, page_list);
+                if (is_page_busy(page)) {
+                        if (pool->dev)
+                                dev_err(pool->dev,
+                                        "dma_pool_destroy %s, %p busy\n",
+                                        pool->name, page->vaddr);
+                        else
+                                printk(KERN_ERR
+                                       "dma_pool_destroy %s, %p busy\n",
+                                       pool->name, page->vaddr);
+                        /* leak the still-in-use consistent memory */
+                        list_del(&page->page_list);
+                        kfree(page);
+                } else
+                        pool_free_page(pool, page);
+        }
+
+        kfree(pool);
+}
+EXPORT_SYMBOL(dma_pool_destroy);
+
+/**
+ * dma_pool_alloc - get a block of consistent memory
+ * @pool: dma pool that will produce the block
+ * @mem_flags: GFP_* bitmask
+ * @handle: pointer to dma address of block
+ *
+ * This returns the kernel virtual address of a currently unused block,
+ * and reports its dma address through the handle.
+ * If such a memory block can't be allocated, %NULL is returned.
+ */
+void *dma_pool_alloc(struct dma_pool *pool, gfp_t mem_flags,
+                     dma_addr_t *handle)
+{
+        unsigned long flags;
+        struct dma_page *page;
+        size_t offset;
+        void *retval;
+
+        spin_lock_irqsave(&pool->lock, flags);
+ restart:
+        list_for_each_entry(page, &pool->page_list, page_list) {
+                if (page->offset < pool->allocation)
+                        goto ready;
+        }
+        page = pool_alloc_page(pool, GFP_ATOMIC);
+        if (!page) {
+                if (mem_flags & __GFP_WAIT) {
+                        DECLARE_WAITQUEUE(wait, current);
+
+                        __set_current_state(TASK_INTERRUPTIBLE);
+                        __add_wait_queue(&pool->waitq, &wait);
+                        spin_unlock_irqrestore(&pool->lock, flags);
+
+                        schedule_timeout(POOL_TIMEOUT_JIFFIES);
+
+                        spin_lock_irqsave(&pool->lock, flags);
+                        __remove_wait_queue(&pool->waitq, &wait);
+                        goto restart;
+                }
+                retval = NULL;
+                goto done;
+        }
+
+ ready:
+        page->in_use++;
+        offset = page->offset;
+        page->offset = *(int *)(page->vaddr + offset);
+        retval = offset + page->vaddr;
+        *handle = offset + page->dma;
+#ifdef  CONFIG_DEBUG_SLAB
+        memset(retval, POOL_POISON_ALLOCATED, pool->size);
+#endif
+ done:
+        spin_unlock_irqrestore(&pool->lock, flags);
+        return retval;
+}
+EXPORT_SYMBOL(dma_pool_alloc);
+
+static struct dma_page *pool_find_page(struct dma_pool *pool, dma_addr_t dma)
+{
+        unsigned long flags;
+        struct dma_page *page;
+
+        spin_lock_irqsave(&pool->lock, flags);
+        list_for_each_entry(page, &pool->page_list, page_list) {
+                if (dma < page->dma)
+                        continue;
+                if (dma < (page->dma + pool->allocation))
+                        goto done;
+        }
+        page = NULL;
+ done:
+        spin_unlock_irqrestore(&pool->lock, flags);
+        return page;
+}
+
+/**
+ * dma_pool_free - put block back into dma pool
+ * @pool: the dma pool holding the block
+ * @vaddr: virtual address of block
+ * @dma: dma address of block
+ *
+ * Caller promises neither device nor driver will again touch this block
+ * unless it is first re-allocated.
+ */
+void dma_pool_free(struct dma_pool *pool, void *vaddr, dma_addr_t dma)
+{
+        struct dma_page *page;
+        unsigned long flags;
+        unsigned int offset;
+
+        page = pool_find_page(pool, dma);
+        if (!page) {
+                if (pool->dev)
+                        dev_err(pool->dev,
+                                "dma_pool_free %s, %p/%lx (bad dma)\n",
+                                pool->name, vaddr, (unsigned long)dma);
+                else
+                        printk(KERN_ERR "dma_pool_free %s, %p/%lx (bad dma)\n",
+                               pool->name, vaddr, (unsigned long)dma);
+                return;
+        }
+
+        offset = vaddr - page->vaddr;
+#ifdef  CONFIG_DEBUG_SLAB
+        if ((dma - page->dma) != offset) {
+                if (pool->dev)
+                        dev_err(pool->dev,
+                                "dma_pool_free %s, %p (bad vaddr)/%Lx\n",
+                                pool->name, vaddr, (unsigned long long)dma);
+                else
+                        printk(KERN_ERR
+                               "dma_pool_free %s, %p (bad vaddr)/%Lx\n",
+                               pool->name, vaddr, (unsigned long long)dma);
+                return;
+        }
+        {
+                unsigned int chain = page->offset;
+                while (chain < pool->allocation) {
+                        if (chain != offset) {
+                                chain = *(int *)(page->vaddr + chain);
+                                continue;
+                        }
+                        if (pool->dev)
+                                dev_err(pool->dev, "dma_pool_free %s, dma %Lx "
+                                        "already free\n", pool->name,
+                                        (unsigned long long)dma);
+                        else
+                                printk(KERN_ERR "dma_pool_free %s, dma %Lx "
+                                        "already free\n", pool->name,
+                                        (unsigned long long)dma);
+                        return;
+                }
+        }
+        memset(vaddr, POOL_POISON_FREED, pool->size);
+#endif
+
+        spin_lock_irqsave(&pool->lock, flags);
+        page->in_use--;
+        *(int *)vaddr = page->offset;
+        page->offset = offset;
+        if (waitqueue_active(&pool->waitq))
+                wake_up_locked(&pool->waitq);
+        /*
+         * Resist a temptation to do
+         *    if (!is_page_busy(page)) pool_free_page(pool, page);
+         * Better have a few empty pages hang around.
+         */
+        spin_unlock_irqrestore(&pool->lock, flags);
+}
+EXPORT_SYMBOL(dma_pool_free);
+
+/*
+ * Managed DMA pool
+ */
+static void dmam_pool_release(struct device *dev, void *res)
+{
+        struct dma_pool *pool = *(struct dma_pool **)res;
+
+        dma_pool_destroy(pool);
+}
+
+static int dmam_pool_match(struct device *dev, void *res, void *match_data)
+{
+        return *(struct dma_pool **)res == match_data;
+}
+
+/**
+ * dmam_pool_create - Managed dma_pool_create()
+ * @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
+ * @allocation: returned blocks won't cross this boundary (or zero)
+ *
+ * Managed dma_pool_create().  DMA pool created with this function is
+ * automatically destroyed on driver detach.
+ */
+struct dma_pool *dmam_pool_create(const char *name, struct device *dev,
+                                  size_t size, size_t align, size_t allocation)
+{
+        struct dma_pool **ptr, *pool;
+
+        ptr = devres_alloc(dmam_pool_release, sizeof(*ptr), GFP_KERNEL);
+        if (!ptr)
+                return NULL;
+
+        pool = *ptr = dma_pool_create(name, dev, size, align, allocation);
+        if (pool)
+                devres_add(dev, ptr);
+        else
+                devres_free(ptr);
+
+        return pool;
+}
+EXPORT_SYMBOL(dmam_pool_create);
+
+/**
+ * dmam_pool_destroy - Managed dma_pool_destroy()
+ * @pool: dma pool that will be destroyed
+ *
+ * Managed dma_pool_destroy().
+ */
+void dmam_pool_destroy(struct dma_pool *pool)
+{
+        struct device *dev = pool->dev;
+
+        dma_pool_destroy(pool);
+        WARN_ON(devres_destroy(dev, dmam_pool_release, dmam_pool_match, pool));
+}
+EXPORT_SYMBOL(dmam_pool_destroy);