netdev - [net-next PATCH 1/2] mm: add dma_addr

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Date:   Mon, 11 Feb 2019 17:06:46 +0100
From:   Jesper Dangaard Brouer <brouer@...hat.com>
To:     netdev@...r.kernel.org, linux-mm@...ck.org
Cc:     Toke Høiland-Jørgensen <toke@...e.dk>,
        Ilias Apalodimas <ilias.apalodimas@...aro.org>,
        willy@...radead.org, Saeed Mahameed <saeedm@...lanox.com>,
        Jesper Dangaard Brouer <brouer@...hat.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        mgorman@...hsingularity.net,
        "David S. Miller" <davem@...emloft.net>,
        Tariq Toukan <tariqt@...lanox.com>
Subject: [net-next PATCH 1/2] mm: add dma_addr_t to struct page

The page_pool API is using page->private to store DMA addresses.
As pointed out by David Miller we can't use that on 32-bit architectures
with 64-bit DMA

This patch adds a new dma_addr_t struct to allow storing DMA addresses

Signed-off-by: Jesper Dangaard Brouer <brouer@...hat.com>
Signed-off-by: Ilias Apalodimas <ilias.apalodimas@...aro.org>
---
 include/linux/mm_types.h |    8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 2c471a2c43fa..3060700752cc 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -95,6 +95,14 @@ struct page {
 			 */
 			unsigned long private;
 		};
+		struct {	/* page_pool used by netstack */
+			/**
+			 * @dma_addr: Page_pool need to store DMA-addr, and
+			 * cannot use @private, as DMA-mappings can be 64-bit
+			 * even on 32-bit Architectures.
+			 */
+			dma_addr_t dma_addr; /* Shares area with @lru */
+		};
 		struct {	/* slab, slob and slub */
 			union {
 				struct list_head slab_list;	/* uses lru */