[PATCH net-next v2 2/2] page_pool: optimize the cpu sync operation when DMA mapping

[Yunsheng Lin]

If the DMA_ATTR_SKIP_CPU_SYNC is not set, cpu syncing is
also done in dma_map_page_attrs(), so set the attrs according
to pool->p.flags to avoid calling cpu sync function again.

Signed-off-by: Yunsheng Lin <linyunsheng@xxxxxxxxxx>
---
 net/core/page_pool.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/net/core/page_pool.c b/net/core/page_pool.c
index 1a69784..3df5554 100644
--- a/net/core/page_pool.c
+++ b/net/core/page_pool.c
@@ -191,8 +191,12 @@ static void page_pool_dma_sync_for_device(struct page_pool *pool,
 
 static bool page_pool_dma_map(struct page_pool *pool, struct page *page)
 {
+	unsigned long attrs = DMA_ATTR_SKIP_CPU_SYNC;
 	dma_addr_t dma;
 
+	if (pool->p.flags & PP_FLAG_DMA_SYNC_DEV)
+		attrs = 0;
+
 	/* 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)
@@ -200,15 +204,12 @@ static bool page_pool_dma_map(struct page_pool *pool, struct page *page)
 	 */
 	dma = dma_map_page_attrs(pool->p.dev, page, 0,
 				 (PAGE_SIZE << pool->p.order),
-				 pool->p.dma_dir, DMA_ATTR_SKIP_CPU_SYNC);
+				 pool->p.dma_dir, attrs);
 	if (dma_mapping_error(pool->p.dev, dma))
 		return false;
 
 	page_pool_set_dma_addr(page, dma);
 
-	if (pool->p.flags & PP_FLAG_DMA_SYNC_DEV)
-		page_pool_dma_sync_for_device(pool, page, pool->p.max_len);
-
 	return true;
 }
 
-- 
2.7.4