dmapool: Validate parameters to dma_pool_create

Check that 'align' is a power of two, like the API specifies.
Align 'size' to 'align' correctly -- the current code has an off-by-one.
The ALIGN macro in kernel.h doesn't.
Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
Acked-by: David S. Miller <davem@davemloft.net>

mm/dmapool.c

@@ -106,17 +106,18 @@ struct dma_pool *dma_pool_create(const char *name, struct device *dev,
 {
 	struct dma_pool *retval;
 
-	if (align == 0)
+	if (align == 0) {
 		align = 1;
-	if (size == 0)
+	} else if (align & (align - 1)) {
 		return NULL;
-	else if (size < align)
-		size = align;
-	else if ((size % align) != 0) {
-		size += align + 1;
-		size &= ~(align - 1);
 	}
 
+	if (size == 0)
+		return NULL;
+
+	if ((size % align) != 0)
+		size = ALIGN(size, align);
+
 	if (allocation == 0) {
 		if (PAGE_SIZE < size)
 			allocation = size;