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=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable 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 F216EC433E2 for ; Fri, 11 Sep 2020 14:35:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A3010222BA for ; Fri, 11 Sep 2020 14:35:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1599834900; bh=IdkLrxN9felV/k85cV/tWxYZltvg/docZKXEUelkiME=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=GraM/btmHbdAzBlh2G6+cWQqOOfgCKn3B4SJI/kY+mEDSgv1gCg8lugIEXvE13pf+ qfsvZVRI5d5FnDZ3tCjPnloN13feN9f4g+1ARUw2JzqeMcThQL78LYnqdJ6VEoZseE MtOjajLxtrZHkru/ksX04ql56aYq4V2UWA6LHLcY= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726083AbgIKOex (ORCPT ); Fri, 11 Sep 2020 10:34:53 -0400 Received: from mail.kernel.org ([198.145.29.99]:57610 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726216AbgIKNMA (ORCPT ); Fri, 11 Sep 2020 09:12:00 -0400 Received: from localhost (83-86-74-64.cable.dynamic.v4.ziggo.nl [83.86.74.64]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 14B8222472; Fri, 11 Sep 2020 13:00:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1599829251; bh=IdkLrxN9felV/k85cV/tWxYZltvg/docZKXEUelkiME=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=gr2ggh4sEFCTOMmPEFEEU318vCX99Dp+c1FU9ndLMvnbqNTXjbLjPBa3VO6+dnHa0 SSrbRT9P8OI/m7xWUjefR1p/DDiyxVrTSSLAcFdfiSgfJVTanwaNwmrJ6r/wM9Zg7z ihGdNlcYYEH5G7u0PyUbbaJyMwksG+jY6jWufHis= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Rob Sherwood , Jakub Kicinski , "David S. Miller" Subject: [PATCH 4.19 7/8] net: disable netpoll on fresh napis Date: Fri, 11 Sep 2020 14:54:54 +0200 Message-Id: <20200911125422.055844958@linuxfoundation.org> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20200911125421.695645838@linuxfoundation.org> References: <20200911125421.695645838@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Jakub Kicinski [ Upstream commit 96e97bc07e90f175a8980a22827faf702ca4cb30 ] napi_disable() makes sure to set the NAPI_STATE_NPSVC bit to prevent netpoll from accessing rings before init is complete. However, the same is not done for fresh napi instances in netif_napi_add(), even though we expect NAPI instances to be added as disabled. This causes crashes during driver reconfiguration (enabling XDP, changing the channel count) - if there is any printk() after netif_napi_add() but before napi_enable(). To ensure memory ordering is correct we need to use RCU accessors. Reported-by: Rob Sherwood Fixes: 2d8bff12699a ("netpoll: Close race condition between poll_one_napi and napi_disable") Signed-off-by: Jakub Kicinski Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/core/dev.c | 3 ++- net/core/netpoll.c | 2 +- 2 files changed, 3 insertions(+), 2 deletions(-) --- a/net/core/dev.c +++ b/net/core/dev.c @@ -6196,12 +6196,13 @@ void netif_napi_add(struct net_device *d pr_err_once("netif_napi_add() called with weight %d on device %s\n", weight, dev->name); napi->weight = weight; - list_add(&napi->dev_list, &dev->napi_list); napi->dev = dev; #ifdef CONFIG_NETPOLL napi->poll_owner = -1; #endif set_bit(NAPI_STATE_SCHED, &napi->state); + set_bit(NAPI_STATE_NPSVC, &napi->state); + list_add_rcu(&napi->dev_list, &dev->napi_list); napi_hash_add(napi); } EXPORT_SYMBOL(netif_napi_add); --- a/net/core/netpoll.c +++ b/net/core/netpoll.c @@ -161,7 +161,7 @@ static void poll_napi(struct net_device struct napi_struct *napi; int cpu = smp_processor_id(); - list_for_each_entry(napi, &dev->napi_list, dev_list) { + list_for_each_entry_rcu(napi, &dev->napi_list, dev_list) { if (cmpxchg(&napi->poll_owner, -1, cpu) == -1) { poll_one_napi(napi); smp_store_release(&napi->poll_owner, -1);