[PATCHv3 4/5] arm: use genalloc for the atomic pool

Laura Abbott
2014-06-17T01:40:23Z

ARM currently uses a bitmap for tracking atomic allocations.
genalloc already handles this type of memory pool allocation
so switch to using that instead.

Signed-off-by: Laura Abbott <lauraa@codeaurora.org>
---
arch/arm/Kconfig | 1 +
arch/arm/mm/dma-mapping.c | 144 ++++++++++++++--------------------------------
2 files changed, 45 insertions(+), 100 deletions(-)

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 87b63fd..71899da 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -13,6 +13,7 @@ config ARM
select CLONE_BACKWARDS
select CPU_PM if (SUSPEND || CPU_IDLE)
select DCACHE_WORD_ACCESS if HAVE_EFFICIENT_UNALIGNED_ACCESS
+ select GENERIC_ALLOCATOR
select GENERIC_ATOMIC64 if (CPU_V7M || CPU_V6 || !CPU_32v6K || !AEABI)
select GENERIC_CLOCKEVENTS_BROADCAST if SMP
select GENERIC_IDLE_POLL_SETUP
diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
index f5190ac..30edbd4 100644
--- a/arch/arm/mm/dma-mapping.c
+++ b/arch/arm/mm/dma-mapping.c
@@ -26,6 +26,7 @@
#include <linux/io.h>
#include <linux/vmalloc.h>
#include <linux/sizes.h>
+#include <linux/genalloc.h>

#include <asm/memory.h>
#include <asm/highmem.h>
@@ -313,40 +314,31 @@ static void __dma_free_remap(void *cpu_addr, size_t size)
}

#define DEFAULT_DMA_COHERENT_POOL_SIZE SZ_256K
+static struct gen_pool *atomic_pool;

-struct dma_pool {
- size_t size;
- spinlock_t lock;
- unsigned long *bitmap;
- unsigned long nr_pages;
- void *vaddr;
- struct page **pages;
-};
-
-static struct dma_pool atomic_pool = {
- .size = DEFAULT_DMA_COHERENT_POOL_SIZE,
-};
+static size_t atomic_pool_size = DEFAULT_DMA_COHERENT_POOL_SIZE;

static int __init early_coherent_pool(char *p)
{
- atomic_pool.size = memparse(p, &p);
+ atomic_pool_size = memparse(p, &p);
return 0;
}
early_param("coherent_pool", early_coherent_pool);

+
void __init init_dma_coherent_pool_size(unsigned long size)
{
/*
* Catch any attempt to set the pool size too late.
*/
- BUG_ON(atomic_pool.vaddr);
+ BUG_ON(atomic_pool);

/*
* Set architecture specific coherent pool size only if
* it has not been changed by kernel command line parameter.
*/
- if (atomic_pool.size == DEFAULT_DMA_COHERENT_POOL_SIZE)
- atomic_pool.size = size;
+ if (atomic_pool_size == DEFAULT_DMA_COHERENT_POOL_SIZE)
+ atomic_pool_size = size;
}

/*
@@ -354,52 +346,44 @@ void __init init_dma_coherent_pool_size(unsigned long size)
*/
static int __init atomic_pool_init(void)
{
- struct dma_pool *pool = &atomic_pool;
pgprot_t prot = pgprot_dmacoherent(PAGE_KERNEL);
gfp_t gfp = GFP_KERNEL | GFP_DMA;
- unsigned long nr_pages = pool->size >> PAGE_SHIFT;
- unsigned long *bitmap;
struct page *page;
- struct page **pages;
void *ptr;
- int bitmap_size = BITS_TO_LONGS(nr_pages) * sizeof(long);

- bitmap = kzalloc(bitmap_size, GFP_KERNEL);
- if (!bitmap)
- goto no_bitmap;
-
- pages = kzalloc(nr_pages * sizeof(struct page *), GFP_KERNEL);
- if (!pages)
- goto no_pages;
+ atomic_pool = gen_pool_create(PAGE_SHIFT, -1);
+ if (!atomic_pool)
+ goto out;

if (dev_get_cma_area(NULL))
- ptr = __alloc_from_contiguous(NULL, pool->size, prot, &page,
- atomic_pool_init);
+ ptr = __alloc_from_contiguous(NULL, atomic_pool_size, prot,
+ &page, atomic_pool_init);
else
- ptr = __alloc_remap_buffer(NULL, pool->size, gfp, prot, &page,
- atomic_pool_init);
+ ptr = __alloc_remap_buffer(NULL, atomic_pool_size, gfp, prot,
+ &page, atomic_pool_init);
if (ptr) {
- int i;
-
- for (i = 0; i < nr_pages; i++)
- pages[i] = page + i;
-
- spin_lock_init(&pool->lock);
- pool->vaddr = ptr;
- pool->pages = pages;
- pool->bitmap = bitmap;
- pool->nr_pages = nr_pages;
- pr_info("DMA: preallocated %u KiB pool for atomic coherent allocations\n",
- (unsigned)pool->size / 1024);
+ int ret;
+
+ ret = gen_pool_add_virt(atomic_pool, (unsigned long)ptr,
+ page_to_phys(page),
+ atomic_pool_size, -1);
+ if (ret)
+ goto destroy_genpool;
+
+ gen_pool_set_algo(atomic_pool,
+ gen_pool_first_fit_order_align,
+ (void *)PAGE_SHIFT);
+ pr_info("DMA: preallocated %zd KiB pool for atomic coherent allocations\n",
+ atomic_pool_size / 1024);
return 0;
}

- kfree(pages);
-no_pages:
- kfree(bitmap);
-no_bitmap:
- pr_err("DMA: failed to allocate %u KiB pool for atomic coherent allocation\n",
- (unsigned)pool->size / 1024);
+destroy_genpool:
+ gen_pool_destroy(atomic_pool);
+ atomic_pool = NULL;
+out:
+ pr_err("DMA: failed to allocate %zx KiB pool for atomic coherent allocation\n",
+ atomic_pool_size / 1024);
return -ENOMEM;
}
/*
@@ -494,76 +478,36 @@ static void *__alloc_remap_buffer(struct device *dev, size_t size, gfp_t gfp,

static void *__alloc_from_pool(size_t size, struct page **ret_page)
{
- struct dma_pool *pool = &atomic_pool;
- unsigned int count = PAGE_ALIGN(size) >> PAGE_SHIFT;
- unsigned int pageno;
- unsigned long flags;
+ unsigned long val;
void *ptr = NULL;
- unsigned long align_mask;

- if (!pool->vaddr) {
+ if (!atomic_pool) {
WARN(1, "coherent pool not initialised!\n");
return NULL;
}

- /*
- * Align the region allocation - allocations from pool are rather
- * small, so align them to their order in pages, minimum is a page
- * size. This helps reduce fragmentation of the DMA space.
- */
- align_mask = (1 << get_order(size)) - 1;
-
- spin_lock_irqsave(&pool->lock, flags);
- pageno = bitmap_find_next_zero_area(pool->bitmap, pool->nr_pages,
- 0, count, align_mask);
- if (pageno < pool->nr_pages) {
- bitmap_set(pool->bitmap, pageno, count);
- ptr = pool->vaddr + PAGE_SIZE * pageno;
- *ret_page = pool->pages[pageno];
- } else {
- pr_err_once("ERROR: %u KiB atomic DMA coherent pool is too small!\n"
- "Please increase it with coherent_pool= kernel parameter!\n",
- (unsigned)pool->size / 1024);
+ val = gen_pool_alloc(atomic_pool, size);
+ if (val) {
+ phys_addr_t phys = gen_pool_virt_to_phys(atomic_pool, val);
+
+ *ret_page = phys_to_page(phys);
+ ptr = (void *)val;
}
- spin_unlock_irqrestore(&pool->lock, flags);

return ptr;
}

static bool __in_atomic_pool(void *start, size_t size)
{
- struct dma_pool *pool = &atomic_pool;
- void *end = start + size;
- void *pool_start = pool->vaddr;
- void *pool_end = pool->vaddr + pool->size;
-
- if (start < pool_start || start >= pool_end)
- return false;
-
- if (end <= pool_end)
- return true;
-
- WARN(1, "Wrong coherent size(%p-%p) from atomic pool(%p-%p)\n",
- start, end - 1, pool_start, pool_end - 1);
-
- return false;
+ return addr_in_gen_pool(atomic_pool, (unsigned long)start, size);
}

static int __free_from_pool(void *start, size_t size)
{
- struct dma_pool *pool = &atomic_pool;
- unsigned long pageno, count;
- unsigned long flags;
-
if (!__in_atomic_pool(start, size))
return 0;

- pageno = (start - pool->vaddr) >> PAGE_SHIFT;
- count = size >> PAGE_SHIFT;
-
- spin_lock_irqsave(&pool->lock, flags);
- bitmap_clear(pool->bitmap, pageno, count);
- spin_unlock_irqrestore(&pool->lock, flags);
+ gen_pool_free(atomic_pool, (unsigned long)start, size);

return 1;
}