page_pool: disable dma mapping support for 32-bit arch with 64-bit DMA

As the 32-bit arch with 64-bit DMA seems to rare those days,
and page pool might carry a lot of code and complexity for
systems that possibly.

So disable dma mapping support for such systems, if drivers
really want to work on such systems, they have to implement
their own DMA-mapping fallback tracking outside page_pool.

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

diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 7f8ee09c711f411cfd3198333d68f8995437b463..436e0946d691b1f82339a1186245eb8f69ef6e8a 100644 (file)
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -104,18 +104,7 @@ struct page {
                        struct page_pool *pp;
                        unsigned long _pp_mapping_pad;
                        unsigned long dma_addr;
-                       union {
-                               /**
-                                * dma_addr_upper: might require a 64-bit
-                                * value on 32-bit architectures.
-                                */
-                               unsigned long dma_addr_upper;
-                               /**
-                                * For frag page support, not supported in
-                                * 32-bit architectures with 64-bit DMA.
-                                */
-                               atomic_long_t pp_frag_count;
-                       };
+                       atomic_long_t pp_frag_count;
                };
                struct {        /* slab, slob and slub */
                        union {

diff --git a/include/net/page_pool.h b/include/net/page_pool.h
index a4082406a0039611dd9a5d4633d1da8134d07c18..3855f069627f454016dc64558d8accb9c5f31809 100644 (file)
--- a/include/net/page_pool.h
+++ b/include/net/page_pool.h
@@ -216,24 +216,14 @@ static inline void page_pool_recycle_direct(struct page_pool *pool,
        page_pool_put_full_page(pool, page, true);
 }
 
-#define PAGE_POOL_DMA_USE_PP_FRAG_COUNT        \
-               (sizeof(dma_addr_t) > sizeof(unsigned long))
-
 static inline dma_addr_t page_pool_get_dma_addr(struct page *page)
 {
-       dma_addr_t ret = page->dma_addr;
-
-       if (PAGE_POOL_DMA_USE_PP_FRAG_COUNT)
-               ret |= (dma_addr_t)page->dma_addr_upper << 16 << 16;
-
-       return ret;
+       return page->dma_addr;
 }
 
 static inline void page_pool_set_dma_addr(struct page *page, dma_addr_t addr)
 {
        page->dma_addr = addr;
-       if (PAGE_POOL_DMA_USE_PP_FRAG_COUNT)
-               page->dma_addr_upper = upper_32_bits(addr);
 }
 
 static inline void page_pool_set_frag_count(struct page *page, long nr)

diff --git a/net/core/page_pool.c b/net/core/page_pool.c
index 1a6978427d6c86695d214fb75cca94d5240bb5aa..9b60e4301a44fbf3b16c39396b14674bd827e900 100644 (file)
--- a/net/core/page_pool.c
+++ b/net/core/page_pool.c
@@ -49,6 +49,12 @@ static int page_pool_init(struct page_pool *pool,
         * which is the XDP_TX use-case.
         */
        if (pool->p.flags & PP_FLAG_DMA_MAP) {
+               /* DMA-mapping is not supported on 32-bit systems with
+                * 64-bit DMA mapping.
+                */
+               if (sizeof(dma_addr_t) > sizeof(unsigned long))
+                       return -EOPNOTSUPP;
+
                if ((pool->p.dma_dir != DMA_FROM_DEVICE) &&
                    (pool->p.dma_dir != DMA_BIDIRECTIONAL))
                        return -EINVAL;
@@ -69,10 +75,6 @@ static int page_pool_init(struct page_pool *pool,
                 */
        }
 
-       if (PAGE_POOL_DMA_USE_PP_FRAG_COUNT &&
-           pool->p.flags & PP_FLAG_PAGE_FRAG)
-               return -EINVAL;
-
        if (ptr_ring_init(&pool->ring, ring_qsize, GFP_KERNEL) < 0)
                return -ENOMEM;