From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 30729C433DF for ; Wed, 27 May 2020 17:08:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0B81620873 for ; Wed, 27 May 2020 17:08:47 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=cloudflare.com header.i=@cloudflare.com header.b="naGrXBhW" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730012AbgE0RIq (ORCPT ); Wed, 27 May 2020 13:08:46 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41128 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729875AbgE0RIp (ORCPT ); Wed, 27 May 2020 13:08:45 -0400 Received: from mail-ej1-x641.google.com (mail-ej1-x641.google.com [IPv6:2a00:1450:4864:20::641]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 95B9DC03E97D for ; Wed, 27 May 2020 10:08:44 -0700 (PDT) Received: by mail-ej1-x641.google.com with SMTP id y13so7004205eju.2 for ; Wed, 27 May 2020 10:08:44 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cloudflare.com; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=RKJeDOq+HqmTFfnS/vZ8EmCIUcvnA2ca6FYbu52upNA=; b=naGrXBhWjhX2ex2vl2P12O8p4VmykqhgVirqJjE4EEyvoDryLC9vqcA4CTJI/0B/X6 HEdQtUZcyrwPiMj2IDdCiuWgwB5uqjZwfsakCnQLaTowYCL41B5iKbrl9igiRoM3/wsd 8iskYp5ykF+gmIbejeodV3lZ78iojzFcB3W94= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=RKJeDOq+HqmTFfnS/vZ8EmCIUcvnA2ca6FYbu52upNA=; b=MjPAlczIfZ8LV1JdaIpErz3u5Nz7CkNvBdpYLbsXptihFC9Sr6MtaSNz27uDvbJF8S KFKa7rbmyHVQ73xqQEe/d2/RbDR5eXr9CuBA1IiuLlvyvHtuf7CRanrjLn+Webz/uZF8 0laFjqkQA1q+rIla1qqFnPRclRv6AlESk9lNkEqambyJOdnfupG3MOHQm0rXtog/g7qy MbwS2cU0MeYmrmGgaxnayBI+dTwoq1jmB+ISBupgEMjke6VH/UhZnbsCuuhiZUCPkqb/ qLj0muFGwJLLOxZhwYbZutdOh+JJfBGlpaXyjaPUUFhoojVwT4svrfZNMyLJ2l/IDN8O cPjA== X-Gm-Message-State: AOAM5338LkXMENPl23Ba/CMOVo+/0ScQ+8B8TV10LIWs9JlPPcSJqqjf 8xCyFGn3sI6zeRHv9gife6r+0Q== X-Google-Smtp-Source: ABdhPJwoxnIGPgUv5ELsctlJ4MYFhrzjq84+GSTcQL46+ZXJMIy64lmmrjWPcJP/WsaOv0+L/m+1qA== X-Received: by 2002:a17:907:364:: with SMTP id rs4mr6732284ejb.311.1590599323269; Wed, 27 May 2020 10:08:43 -0700 (PDT) Received: from cloudflare.com ([2a02:a310:c262:aa00:b35e:8938:2c2a:ba8b]) by smtp.gmail.com with ESMTPSA id ch8sm3169670ejb.53.2020.05.27.10.08.42 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 27 May 2020 10:08:42 -0700 (PDT) From: Jakub Sitnicki To: bpf@vger.kernel.org Cc: netdev@vger.kernel.org, kernel-team@cloudflare.com Subject: [PATCH bpf-next 1/8] flow_dissector: Don't grab update-side lock on prog detach from pre_exit Date: Wed, 27 May 2020 19:08:33 +0200 Message-Id: <20200527170840.1768178-2-jakub@cloudflare.com> X-Mailer: git-send-email 2.25.4 In-Reply-To: <20200527170840.1768178-1-jakub@cloudflare.com> References: <20200527170840.1768178-1-jakub@cloudflare.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org When there are no references to struct net left, that is check_net(net) is false, we don't need to synchronize updates to flow_dissector prog with BPF prog attach/detach callbacks. That allows us to pull locking up from the shared detach routine and into the bpf prog detach callback. Signed-off-by: Jakub Sitnicki --- net/core/flow_dissector.c | 16 ++++++++++------ 1 file changed, 10 insertions(+), 6 deletions(-) diff --git a/net/core/flow_dissector.c b/net/core/flow_dissector.c index 5dceed467f64..73cc085dc2b7 100644 --- a/net/core/flow_dissector.c +++ b/net/core/flow_dissector.c @@ -164,22 +164,26 @@ static int flow_dissector_bpf_prog_detach(struct net *net) { struct bpf_prog *attached; - mutex_lock(&flow_dissector_mutex); + /* No need for update-side lock when net is going away. */ attached = rcu_dereference_protected(net->flow_dissector_prog, + !check_net(net) || lockdep_is_held(&flow_dissector_mutex)); - if (!attached) { - mutex_unlock(&flow_dissector_mutex); + if (!attached) return -ENOENT; - } RCU_INIT_POINTER(net->flow_dissector_prog, NULL); bpf_prog_put(attached); - mutex_unlock(&flow_dissector_mutex); return 0; } int skb_flow_dissector_bpf_prog_detach(const union bpf_attr *attr) { - return flow_dissector_bpf_prog_detach(current->nsproxy->net_ns); + int ret; + + mutex_lock(&flow_dissector_mutex); + ret = flow_dissector_bpf_prog_detach(current->nsproxy->net_ns); + mutex_unlock(&flow_dissector_mutex); + + return ret; } static void __net_exit flow_dissector_pernet_pre_exit(struct net *net) -- 2.25.4