Thread (31 messages) 31 messages, 6 authors, 2023-06-24

Re: [PATCH net-next v3 1/4] page_pool: frag API support for 32-bit arch with 64-bit DMA

From: Jesper Dangaard Brouer <hidden>
Date: 2023-06-09 15:03:50
Also in: linux-rdma, lkml

On 09/06/2023 15.17, Yunsheng Lin wrote:
quoted hunk ↗ jump to hunk
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
index a7c526ee5024..cd4ac378cc63 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
@@ -832,6 +832,15 @@ static int mlx5e_alloc_rq(struct mlx5e_params *params,
  		/* Create a page_pool and register it with rxq */
  		struct page_pool_params pp_params = { 0 };
  
+		/* Return error here to aoivd writing to page->pp_frag_count in
                                         ^^^^^
Typo
quoted hunk ↗ jump to hunk
+		 * mlx5e_page_release_fragmented() for page->pp_frag_count is not
+		 * usable for arch with PAGE_POOL_DMA_USE_PP_FRAG_COUNT being true.
+		 */
+		if (PAGE_POOL_DMA_USE_PP_FRAG_COUNT) {
+			err = -EINVAL;
+			goto err_free_by_rq_type;
+		}
+
  		pp_params.order     = 0;
  		pp_params.flags     = PP_FLAG_DMA_MAP | PP_FLAG_DMA_SYNC_DEV | PP_FLAG_PAGE_FRAG;
  		pp_params.pool_size = pool_size;
diff --git a/include/net/page_pool.h b/include/net/page_pool.h
index 126f9e294389..5c7f7501f300 100644
--- a/include/net/page_pool.h
+++ b/include/net/page_pool.h
@@ -33,6 +33,7 @@
  #include <linux/mm.h> /* Needed by ptr_ring */
  #include <linux/ptr_ring.h>
  #include <linux/dma-direction.h>
+#include <linux/dma-mapping.h>
  
  #define PP_FLAG_DMA_MAP		BIT(0) /* Should page_pool do the DMA
  					* map/unmap
@@ -50,6 +51,9 @@
  				 PP_FLAG_DMA_SYNC_DEV |\
  				 PP_FLAG_PAGE_FRAG)
  
+#define PAGE_POOL_DMA_USE_PP_FRAG_COUNT	\
+		(sizeof(dma_addr_t) > sizeof(unsigned long))
+
I have a problem with the name PAGE_POOL_DMA_USE_PP_FRAG_COUNT
because it is confusing to read in an if-statement.

Proposals rename to:  DMA_OVERLAP_PP_FRAG_COUNT
  Or:  MM_DMA_OVERLAP_PP_FRAG_COUNT
  Or:  DMA_ADDR_OVERLAP_PP_FRAG_COUNT

Notice how I also removed the prefix PAGE_POOL_ because this is a 
MM-layer constraint and not a property of page_pool.


--Jesper
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