4.17-stable review patch. If anyone has any objections, please let me know.
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From: Saeed Mahameed saeedm@mellanox.com
[ Upstream commit 432e629e56432064761be63bcd5e263c0920430d ]
When a new rx packet arrives, the rx path will decide whether to reuse the remainder of the page or not according to one of the below conditions: 1. frag_info->frag_stride == PAGE_SIZE / 2 2. frags->page_offset + frag_info->frag_size > PAGE_SIZE;
The first condition is no met for when XDP is set. For XDP, page_offset is always set to priv->rx_headroom which is XDP_PACKET_HEADROOM and frag_info->frag_size is around mtu size + some padding, still the 2nd release condition will hold since XDP_PACKET_HEADROOM + 1536 < PAGE_SIZE, as a result the page will not be released and will be _wrongly_ reused for next free rx descriptor.
In XDP there is an assumption to have a page per packet and reuse can break such assumption and might cause packet data corruptions.
Fix this by adding an extra condition (!priv->rx_headroom) to the 2nd case to avoid page reuse when XDP is set, since rx_headroom is set to 0 for non XDP setup and set to XDP_PACKET_HEADROOM for XDP setup.
No additional cache line is required for the new condition.
Fixes: 34db548bfb95 ("mlx4: add page recycling in receive path") Signed-off-by: Saeed Mahameed saeedm@mellanox.com Signed-off-by: Tariq Toukan tariqt@mellanox.com Suggested-by: Martin KaFai Lau kafai@fb.com CC: Eric Dumazet edumazet@google.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/net/ethernet/mellanox/mlx4/en_rx.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)
--- a/drivers/net/ethernet/mellanox/mlx4/en_rx.c +++ b/drivers/net/ethernet/mellanox/mlx4/en_rx.c @@ -474,10 +474,10 @@ static int mlx4_en_complete_rx_desc(stru { const struct mlx4_en_frag_info *frag_info = priv->frag_info; unsigned int truesize = 0; + bool release = true; int nr, frag_size; struct page *page; dma_addr_t dma; - bool release;
/* Collect used fragments while replacing them in the HW descriptors */ for (nr = 0;; frags++) { @@ -500,7 +500,11 @@ static int mlx4_en_complete_rx_desc(stru release = page_count(page) != 1 || page_is_pfmemalloc(page) || page_to_nid(page) != numa_mem_id(); - } else { + } else if (!priv->rx_headroom) { + /* rx_headroom for non XDP setup is always 0. + * When XDP is set, the above condition will + * guarantee page is always released. + */ u32 sz_align = ALIGN(frag_size, SMP_CACHE_BYTES);
frags->page_offset += sz_align;