From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:46158 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387849AbeGWNbE (ORCPT ); Mon, 23 Jul 2018 09:31:04 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Saeed Mahameed , Tariq Toukan , Martin KaFai Lau , Eric Dumazet , "David S. Miller" Subject: [PATCH 4.14 37/44] net/mlx4_en: Dont reuse RX page when XDP is set Date: Mon, 23 Jul 2018 14:25:13 +0200 Message-Id: <20180723122439.223616587@linuxfoundation.org> In-Reply-To: <20180723122437.447870153@linuxfoundation.org> References: <20180723122437.447870153@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: stable-owner@vger.kernel.org List-ID: 4.14-stable review patch. If anyone has any objections, please let me know. ------------------ From: Saeed Mahameed [ 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 Signed-off-by: Tariq Toukan Suggested-by: Martin KaFai Lau CC: Eric Dumazet Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- 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 @@ -472,10 +472,10 @@ 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++) { @@ -498,7 +498,11 @@ 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;