From patchwork Thu May 12 10:33:21 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "liujian (CE)" X-Patchwork-Id: 12847511 X-Patchwork-Delegate: kuba@kernel.org Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 92ED4C433F5 for ; Thu, 12 May 2022 10:32:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237651AbiELKcf (ORCPT ); Thu, 12 May 2022 06:32:35 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55900 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229503AbiELKcd (ORCPT ); Thu, 12 May 2022 06:32:33 -0400 Received: from szxga08-in.huawei.com (szxga08-in.huawei.com [45.249.212.255]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CFA1C52B2C for ; Thu, 12 May 2022 03:32:31 -0700 (PDT) Received: from canpemm500010.china.huawei.com (unknown [172.30.72.55]) by szxga08-in.huawei.com (SkyGuard) with ESMTP id 4KzSjw100sz1JBlT; Thu, 12 May 2022 18:31:16 +0800 (CST) Received: from huawei.com (10.175.101.6) by canpemm500010.china.huawei.com (7.192.105.118) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Thu, 12 May 2022 18:32:29 +0800 From: Liu Jian To: , , , , , , , CC: Subject: [PATCH net] tcp: Add READ_ONCE() to read tcp_orphan_count Date: Thu, 12 May 2022 18:33:21 +0800 Message-ID: <20220512103322.380405-1-liujian56@huawei.com> X-Mailer: git-send-email 2.17.1 MIME-Version: 1.0 X-Originating-IP: [10.175.101.6] X-ClientProxiedBy: dggems706-chm.china.huawei.com (10.3.19.183) To canpemm500010.china.huawei.com (7.192.105.118) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org X-Patchwork-Delegate: kuba@kernel.org The tcp_orphan_count per-CPU variable is read locklessly, so this commit add the READ_ONCE() to a load in order to avoid below KCSAN warnning: BUG: KCSAN: data-race in tcp_orphan_count_sum net/ipv4/tcp.c:2476 [inline] BUG: KCSAN: data-race in tcp_orphan_update+0x64/0x100 net/ipv4/tcp.c:2487 race at unknown origin, with read to 0xffff9c63bbdac7a8 of 4 bytes by interrupt on cpu 2: tcp_orphan_count_sum net/ipv4/tcp.c:2476 [inline] tcp_orphan_update+0x64/0x100 net/ipv4/tcp.c:2487 call_timer_fn+0x33/0x210 kernel/time/timer.c:1414 Fixes: 19757cebf0c5 ("tcp: switch orphan_count to bare per-cpu counters") Signed-off-by: Liu Jian --- net/ipv4/tcp.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index cf18fbcbf123..7245609f41e6 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -2718,7 +2718,7 @@ int tcp_orphan_count_sum(void) int i, total = 0; for_each_possible_cpu(i) - total += per_cpu(tcp_orphan_count, i); + total += READ_ONCE(per_cpu(tcp_orphan_count, i)); return max(total, 0); }