dma-mapping: use vmap insted of reimplementing it

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 <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Acked-by: Peter Zijlstra (Intel) <[email protected]>
Cc: Christian Borntraeger <[email protected]>
Cc: Christophe Leroy <[email protected]>
Cc: Daniel Vetter <[email protected]>
Cc: David Airlie <[email protected]>
Cc: Gao Xiang <[email protected]>
Cc: Greg Kroah-Hartman <[email protected]>
Cc: Haiyang Zhang <[email protected]>
Cc: Johannes Weiner <[email protected]>
Cc: "K. Y. Srinivasan" <[email protected]>
Cc: Laura Abbott <[email protected]>
Cc: Mark Rutland <[email protected]>
Cc: Michael Kelley <[email protected]>
Cc: Minchan Kim <[email protected]>
Cc: Nitin Gupta <[email protected]>
Cc: Robin Murphy <[email protected]>
Cc: Sakari Ailus <[email protected]>
Cc: Stephen Hemminger <[email protected]>
Cc: Sumit Semwal <[email protected]>
Cc: Wei Liu <[email protected]>
Cc: Benjamin Herrenschmidt <[email protected]>
Cc: Catalin Marinas <[email protected]>
Cc: Heiko Carstens <[email protected]>
Cc: Paul Mackerras <[email protected]>
Cc: Vasily Gorbik <[email protected]>
Cc: Will Deacon <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Linus Torvalds <[email protected]>

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, size >> PAGE_SHIFT, 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;
 }
 
 /*