net: page_pool: don't use page->private to store dma_addr_t

As pointed out by David Miller the current page_pool implementation
stores dma_addr_t in page->private.
This won't work on 32-bit platforms with 64-bit DMA addresses since the
page->private is an unsigned long and the dma_addr_t a u64.

A previous patch is adding dma_addr_t on struct page to accommodate this.
This patch adapts the page_pool related functions to use the newly added
struct for storing and retrieving DMA addresses from network drivers.

Signed-off-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 9 insertions, 4 deletions

diff --git a/net/core/page_pool.c b/net/core/page_pool.c
index 43a932cb609b..897a69a1477e 100644
--- a/net/core/page_pool.c
+++ b/net/core/page_pool.c
@@ -136,7 +136,9 @@ static struct page *__page_pool_alloc_pages_slow(struct page_pool *pool,
         if (!(pool->p.flags & PP_FLAG_DMA_MAP))
                 goto skip_dma_map;
 
-        /* Setup DMA mapping: use page->private for DMA-addr
+        /* 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(pool->p.dev, page, 0,
@@ -146,7 +148,7 @@ static struct page *__page_pool_alloc_pages_slow(struct page_pool *pool,
                 put_page(page);
                 return NULL;
         }
-        set_page_private(page, dma); /* page->private = dma; */
+        page->dma_addr = dma;
 
 skip_dma_map:
         /* When page just alloc'ed is should/must have refcnt 1. */
@@ -175,13 +177,16 @@ EXPORT_SYMBOL(page_pool_alloc_pages);
 static void __page_pool_clean_page(struct page_pool *pool,
                                    struct page *page)
 {
+        dma_addr_t dma;
+
         if (!(pool->p.flags & PP_FLAG_DMA_MAP))
                 return;
 
+        dma = page->dma_addr;
         /* DMA unmap */
-        dma_unmap_page(pool->p.dev, page_private(page),
+        dma_unmap_page(pool->p.dev, dma,
                        PAGE_SIZE << pool->p.order, pool->p.dma_dir);
-        set_page_private(page, 0);
+        page->dma_addr = 0;
 }
 
 /* Return a page to the page allocator, cleaning up our state */