[PATCH 04/28] dma-mapping: use vmap insted of reimplementing it

From: Christoph Hellwig
Date: Wed Apr 08 2020 - 08:00:06 EST


Replace the open coded instance of vmap with the actual function. In
the non-contiguous (IOMMU) case this requires an extra find_vm_area,
but given that this isn't a fast path function that is a small price
to pay.

Signed-off-by: Christoph Hellwig <hch@xxxxxx>
---
kernel/dma/remap.c | 48 ++++++++++++----------------------------------
1 file changed, 12 insertions(+), 36 deletions(-)

diff --git a/kernel/dma/remap.c b/kernel/dma/remap.c
index d14cbc83986a..7a8ba60951e8 100644
--- a/kernel/dma/remap.c
+++ b/kernel/dma/remap.c
@@ -20,23 +20,6 @@ struct page **dma_common_find_pages(void *cpu_addr)
return area->pages;
}

-static struct vm_struct *__dma_common_pages_remap(struct page **pages,
- size_t size, pgprot_t prot, const void *caller)
-{
- struct vm_struct *area;
-
- area = get_vm_area_caller(size, VM_DMA_COHERENT, caller);
- if (!area)
- return NULL;
-
- if (map_vm_area(area, prot, pages)) {
- vunmap(area->addr);
- return NULL;
- }
-
- return area;
-}
-
/*
* Remaps an array of PAGE_SIZE pages into another vm_area.
* Cannot be used in non-sleeping contexts
@@ -44,15 +27,12 @@ static struct vm_struct *__dma_common_pages_remap(struct page **pages,
void *dma_common_pages_remap(struct page **pages, size_t size,
pgprot_t prot, const void *caller)
{
- struct vm_struct *area;
+ void *vaddr;

- area = __dma_common_pages_remap(pages, size, prot, caller);
- if (!area)
- return NULL;
-
- area->pages = pages;
-
- return area->addr;
+ vaddr = vmap(pages, count, VM_DMA_COHERENT, prot);
+ if (vaddr)
+ find_vm_area(vaddr)->pages = pages;
+ return vaddr;
}

/*
@@ -62,24 +42,20 @@ void *dma_common_pages_remap(struct page **pages, size_t size,
void *dma_common_contiguous_remap(struct page *page, size_t size,
pgprot_t prot, const void *caller)
{
- int i;
+ int count = size >> PAGE_SHIFT;
struct page **pages;
- struct vm_struct *area;
+ void *vaddr;
+ int i;

- pages = kmalloc(sizeof(struct page *) << get_order(size), GFP_KERNEL);
+ pages = kmalloc_array(count, sizeof(struct page *), GFP_KERNEL);
if (!pages)
return NULL;
-
- for (i = 0; i < (size >> PAGE_SHIFT); i++)
+ for (i = 0; i < count; i++)
pages[i] = nth_page(page, i);
-
- area = __dma_common_pages_remap(pages, size, prot, caller);
-
+ vaddr = vmap(pages, count, VM_DMA_COHERENT, prot);
kfree(pages);

- if (!area)
- return NULL;
- return area->addr;
+ return vaddr;
}

/*
--
2.25.1