[net V2 4/5] net/mlx5e: Set page to null in case dma mapping fails

[Saeed Mahameed]

From: Inbar Karmy <inb...@mellanox.com>

Currently, when dma mapping fails, put_page is called,
but the page is not set to null. Later, in the page_reuse treatment in
mlx5e_free_rx_descs(), mlx5e_page_release() is called for the second time,
improperly doing dma_unmap (for a non-mapped address) and an extra put_page.
Prevent this by nullifying the page pointer when dma_map fails.

Fixes: accd58833237 ("net/mlx5e: Introduce RX Page-Reuse")
Signed-off-by: Inbar Karmy <inb...@mellanox.com>
Reviewed-by: Tariq Toukan <tar...@mellanox.com>
Cc: kernel-t...@fb.com
Signed-off-by: Saeed Mahameed <sae...@mellanox.com>
---
 drivers/net/ethernet/mellanox/mlx5/core/en_rx.c | 12 +++++-------
 1 file changed, 5 insertions(+), 7 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c 
b/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c
index 15a1687483cc..91b1b0938931 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c
@@ -215,22 +215,20 @@ static inline bool mlx5e_rx_cache_get(struct mlx5e_rq *rq,
 static inline int mlx5e_page_alloc_mapped(struct mlx5e_rq *rq,
                                          struct mlx5e_dma_info *dma_info)
 {
-       struct page *page;
-
        if (mlx5e_rx_cache_get(rq, dma_info))
                return 0;
 
-       page = dev_alloc_pages(rq->buff.page_order);
-       if (unlikely(!page))
+       dma_info->page = dev_alloc_pages(rq->buff.page_order);
+       if (unlikely(!dma_info->page))
                return -ENOMEM;
 
-       dma_info->addr = dma_map_page(rq->pdev, page, 0,
+       dma_info->addr = dma_map_page(rq->pdev, dma_info->page, 0,
                                      RQ_PAGE_SIZE(rq), rq->buff.map_dir);
        if (unlikely(dma_mapping_error(rq->pdev, dma_info->addr))) {
-               put_page(page);
+               put_page(dma_info->page);
+               dma_info->page = NULL;
                return -ENOMEM;
        }
-       dma_info->page = page;
 
        return 0;
 }
-- 
2.13.6