From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jesper Dangaard Brouer Subject: [net PATCH 0/3] Fix two teardown bugs for BPF maps cpumap and devmap Date: Wed, 08 Aug 2018 23:00:29 +0200 Message-ID: <153376197849.14272.8201612461878004477.stgit@firesoul> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Cc: Daniel Borkmann , Alexei Starovoitov , jhsiao@redhat.com To: netdev@vger.kernel.org, Jesper Dangaard Brouer Return-path: Received: from mx3-rdu2.redhat.com ([66.187.233.73]:44864 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727530AbeHHXV4 (ORCPT ); Wed, 8 Aug 2018 19:21:56 -0400 Sender: netdev-owner@vger.kernel.org List-ID: Removing entries from cpumap and devmap, goes through a number of syncronization steps to make sure no new xdp_frames can be enqueued. But there is a small chance, that xdp_frames remains which have not been flushed/processed yet. Flushing these during teardown, happens from RCU context and not as usual under RX NAPI context. The optimization introduced in commt 389ab7f01af9 ("xdp: introduce xdp_return_frame_rx_napi"), missed that the flush operation can also be called from RCU context. Thus, we cannot always use the xdp_return_frame_rx_napi call, which take advantage of the protection provided by XDP RX running under NAPI protection. The samples/bpf xdp_redirect_cpu have a --stress-mode, that is adjusted to easier reproduce (verified by Red Hat QA). --- Jesper Dangaard Brouer (3): xdp: fix bug in cpumap teardown code path samples/bpf: xdp_redirect_cpu adjustment to reproduce teardown race easier xdp: fix bug in devmap teardown code path kernel/bpf/cpumap.c | 15 +++++++++------ kernel/bpf/devmap.c | 14 +++++++++----- samples/bpf/xdp_redirect_cpu_kern.c | 2 +- samples/bpf/xdp_redirect_cpu_user.c | 4 ++-- 4 files changed, 21 insertions(+), 14 deletions(-)