Hi Marek,
Marek Szyprowski m.szyprowski@samsung.com wrote @ Wed, 22 Aug 2012 14:04:26 +0200:
Hi Hiroshi,
On Wednesday, August 22, 2012 12:20 PM Hiroshi Doyu wrote:
The commit e9da6e9 "ARM: dma-mapping: remove custom consistent dma region" breaks the compatibility with existing drivers. This causes the following kernel oops(*1). That driver has called dma_pool_alloc() to allocate memory from the interrupt context, and it hits BUG_ON(in_interrpt()) in "get_vm_area_caller()". This patch seris fixes this problem with making use of the pre-allocate atomic memory pool which DMA is using in the same way as DMA does now.
Any comment would be really appreciated.
I was working on the similar patches, but You were faster. ;-)
Thank you for reviewing my patches.
Basically the patch no 1 and 2 are fine, but I don't like the changes proposed in patch 3 and 4. You should not alter the attributes provided by the user nor make any assumptions that such attributes has been provided - drivers are allowed to call dma_alloc_attrs() directly. Please rework your patches to avoid such approach.
Sure. I'll send the series again later.
Instead of making use of DMA_ATTR_NO_KERNEL_MAPPING, I use the following "__in_atomic_pool()" to see if buffer comes from atomic or not at freeing.
From cdf8621fd0876f3e56a55885c27e363893df2c98 Mon Sep 17 00:00:00 2001
From: Hiroshi Doyu hdoyu@nvidia.com Date: Wed, 22 Aug 2012 17:26:29 +0300 Subject: [PATCH 1/1] ARM: dma-mapping: Refactor out to introduce __in_atomic_pool
Check the given range("start", "size") is included in "atomic_pool" or not.
Signed-off-by: Hiroshi Doyu hdoyu@nvidia.com --- arch/arm/mm/dma-mapping.c | 20 +++++++++++++++----- 1 files changed, 15 insertions(+), 5 deletions(-)
diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c index 30bef80..26080ef 100644 --- a/arch/arm/mm/dma-mapping.c +++ b/arch/arm/mm/dma-mapping.c @@ -450,20 +450,30 @@ static void *__alloc_from_pool(size_t size, struct page **ret_page) return ptr; }
-static int __free_from_pool(void *start, size_t size) +static bool __in_atomic_pool(void *start, size_t size) { struct dma_pool *pool = &atomic_pool; - unsigned long pageno, count; - unsigned long flags;
if (start < pool->vaddr || start > pool->vaddr + pool->size) - return 0; + return false;
if (start + size > pool->vaddr + pool->size) { WARN(1, "freeing wrong coherent size from pool\n"); - return 0; + return false; }
+ return true; +} + +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;