From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga06.intel.com ([134.134.136.31]:37348 "EHLO mga06.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753208AbeCVJCo (ORCPT ); Thu, 22 Mar 2018 05:02:44 -0400 From: =?UTF-8?q?Bj=C3=B6rn=20T=C3=B6pel?= To: jeffrey.t.kirsher@intel.com, intel-wired-lan@lists.osuosl.org Cc: =?UTF-8?q?Bj=C3=B6rn=20T=C3=B6pel?= , magnus.karlsson@intel.com, netdev@vger.kernel.org, alexander.h.duyck@intel.com, alexander.duyck@gmail.com Subject: [PATCH] ixgbe: tweak page counting for XDP_REDIRECT Date: Thu, 22 Mar 2018 10:02:36 +0100 Message-Id: <20180322090236.14357-1-bjorn.topel@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: netdev-owner@vger.kernel.org List-ID: From: Björn Töpel The current page counting scheme assumes that the reference count cannot decrease until the received frame is sent to the upper layers of the networking stack. This assumption does not hold for the XDP_REDIRECT action, since a page (pointed out by xdp_buff) can have its reference count decreased via the xdp_do_redirect call. To work around that, we now start off by a large page count and then don't allow a refcount less than two. Signed-off-by: Björn Töpel --- drivers/net/ethernet/intel/ixgbe/ixgbe_main.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c index fb80edbd2739..8dbb2ce06287 100644 --- a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c +++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c @@ -1629,7 +1629,8 @@ static bool ixgbe_alloc_mapped_page(struct ixgbe_ring *rx_ring, bi->dma = dma; bi->page = page; bi->page_offset = ixgbe_rx_offset(rx_ring); - bi->pagecnt_bias = 1; + page_ref_add(page, USHRT_MAX - 1); + bi->pagecnt_bias = USHRT_MAX; rx_ring->rx_stats.alloc_rx_page++; return true; @@ -2039,8 +2040,8 @@ static bool ixgbe_can_reuse_rx_page(struct ixgbe_rx_buffer *rx_buffer) * the pagecnt_bias and page count so that we fully restock the * number of references the driver holds. */ - if (unlikely(!pagecnt_bias)) { - page_ref_add(page, USHRT_MAX); + if (unlikely(pagecnt_bias == 1)) { + page_ref_add(page, USHRT_MAX - 1); rx_buffer->pagecnt_bias = USHRT_MAX; } -- 2.7.4