[PATCH RFC net-next 1/3] net: page_pool: refactor dma_map into own function page_pool_dma_map

[Jesper Dangaard Brouer]

In preparation for next patch, move the dma mapping into its own
function, as this will make it easier to follow the changes.

Signed-off-by: Jesper Dangaard Brouer <bro...@redhat.com>
---
 net/core/page_pool.c |   49 +++++++++++++++++++++++++++++--------------------
 1 file changed, 29 insertions(+), 20 deletions(-)

diff --git a/net/core/page_pool.c b/net/core/page_pool.c
index ad8b0707af04..50d52aa6fbeb 100644
--- a/net/core/page_pool.c
+++ b/net/core/page_pool.c
@@ -180,6 +180,31 @@ static void page_pool_dma_sync_for_device(struct page_pool 
*pool,
                                         pool->p.dma_dir);
 }
 
+static struct page * page_pool_dma_map(struct page_pool *pool,
+                                      struct page *page)
+{
+       dma_addr_t dma;
+
+       /* Setup DMA mapping: use 'struct page' area for storing DMA-addr
+        * since dma_addr_t can be either 32 or 64 bits and does not always fit
+        * into page private data (i.e 32bit cpu with 64bit DMA caps)
+        * This mapping is kept for lifetime of page, until leaving pool.
+        */
+       dma = dma_map_page_attrs(pool->p.dev, page, 0,
+                                (PAGE_SIZE << pool->p.order),
+                                pool->p.dma_dir, DMA_ATTR_SKIP_CPU_SYNC);
+       if (dma_mapping_error(pool->p.dev, dma)) {
+               put_page(page);
+               return NULL;
+       }
+       page->dma_addr = dma;
+
+       if (pool->p.flags & PP_FLAG_DMA_SYNC_DEV)
+               page_pool_dma_sync_for_device(pool, page, pool->p.max_len);
+
+       return page;
+}
+
 /* slow path */
 noinline
 static struct page *__page_pool_alloc_pages_slow(struct page_pool *pool,
@@ -187,7 +212,6 @@ static struct page *__page_pool_alloc_pages_slow(struct 
page_pool *pool,
 {
        struct page *page;
        gfp_t gfp = _gfp;
-       dma_addr_t dma;
 
        /* We could always set __GFP_COMP, and avoid this branch, as
         * prep_new_page() can handle order-0 with __GFP_COMP.
@@ -211,27 +235,12 @@ static struct page *__page_pool_alloc_pages_slow(struct 
page_pool *pool,
        if (!page)
                return NULL;
 
-       if (!(pool->p.flags & PP_FLAG_DMA_MAP))
-               goto skip_dma_map;
-
-       /* Setup DMA mapping: use 'struct page' area for storing DMA-addr
-        * since dma_addr_t can be either 32 or 64 bits and does not always fit
-        * into page private data (i.e 32bit cpu with 64bit DMA caps)
-        * This mapping is kept for lifetime of page, until leaving pool.
-        */
-       dma = dma_map_page_attrs(pool->p.dev, page, 0,
-                                (PAGE_SIZE << pool->p.order),
-                                pool->p.dma_dir, DMA_ATTR_SKIP_CPU_SYNC);
-       if (dma_mapping_error(pool->p.dev, dma)) {
-               put_page(page);
-               return NULL;
+       if (pool->p.flags & PP_FLAG_DMA_MAP) {
+               page = page_pool_dma_map(pool, page);
+               if (!page)
+                       return NULL;
        }
-       page->dma_addr = dma;
-
-       if (pool->p.flags & PP_FLAG_DMA_SYNC_DEV)
-               page_pool_dma_sync_for_device(pool, page, pool->p.max_len);
 
-skip_dma_map:
        /* Track how many pages are held 'in-flight' */
        pool->pages_state_hold_cnt++;