dmapool: rearrange page alloc failure handling

Handle the error in a condition so the good path can be in the normal
flow.

Link: https://lkml.kernel.org/r/[email protected]
Fixes: 2d55c16 ("dmapool: create/destroy cleanup")
Signed-off-by: Keith Busch <[email protected]>
Reviewed-by: Christoph Hellwig <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Tony Battersby <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

Author: keithbusch

mm/dmapool.c

@@ -292,17 +292,19 @@ static struct dma_page *pool_alloc_page(struct dma_pool *pool, gfp_t mem_flags)
 	page = kmalloc(sizeof(*page), mem_flags);
 	if (!page)
 		return NULL;
+
 	page->vaddr = dma_alloc_coherent(pool->dev, pool->allocation,
 					 &page->dma, mem_flags);
-	if (page->vaddr) {
-		pool_init_page(pool, page);
-		pool_initialise_page(pool, page);
-		page->in_use = 0;
-		page->offset = 0;
-	} else {
+	if (!page->vaddr) {
 		kfree(page);
-		page = NULL;
+		return NULL;
 	}
+
+	pool_init_page(pool, page);
+	pool_initialise_page(pool, page);
+	page->in_use = 0;
+	page->offset = 0;
+
 	return page;
 }