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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id CE3D2EB64DD for ; Wed, 9 Aug 2023 11:25:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233699AbjHILZz (ORCPT ); Wed, 9 Aug 2023 07:25:55 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59956 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233701AbjHILZz (ORCPT ); Wed, 9 Aug 2023 07:25:55 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D5908ED for ; Wed, 9 Aug 2023 04:25:54 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 74BDE63272 for ; Wed, 9 Aug 2023 11:25:54 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 88ACFC433C7; Wed, 9 Aug 2023 11:25:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1691580353; bh=9Skas82wgX1XgJWE0u33lrzQI4oiePd3nRtAzWT8SJ0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=tI4J9rH1w3j7NPC7MRo+NyTQ3VEkRp3eZkUwDizC89zTPonlK0BRhZ4lJ2ZNX3Hs3 72y8dTVQWUOjB7NKP2L2QtRvcvhZEBuacYiVPvQp9J3ePbw34mG67FGGOknXmkm2K0 eLc+Zt1jyZ9mzFVet+3a6ID9mwz/m3gQhxlRUZxA= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Eric Dumazet , David Ahern , Kuniyuki Iwashima , Jakub Kicinski , Sasha Levin Subject: [PATCH 4.19 301/323] tcp_metrics: annotate data-races around tm->tcpm_lock Date: Wed, 9 Aug 2023 12:42:19 +0200 Message-ID: <20230809103711.833359406@linuxfoundation.org> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20230809103658.104386911@linuxfoundation.org> References: <20230809103658.104386911@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Eric Dumazet [ Upstream commit 285ce119a3c6c4502585936650143e54c8692788 ] tm->tcpm_lock can be read or written locklessly. Add needed READ_ONCE()/WRITE_ONCE() to document this. Fixes: 51c5d0c4b169 ("tcp: Maintain dynamic metrics in local cache.") Signed-off-by: Eric Dumazet Reviewed-by: David Ahern Reviewed-by: Kuniyuki Iwashima Link: https://lore.kernel.org/r/20230802131500.1478140-4-edumazet@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- net/ipv4/tcp_metrics.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/net/ipv4/tcp_metrics.c b/net/ipv4/tcp_metrics.c index 2d9d95559f5fa..2529b1e6ded0c 100644 --- a/net/ipv4/tcp_metrics.c +++ b/net/ipv4/tcp_metrics.c @@ -59,7 +59,8 @@ static inline struct net *tm_net(struct tcp_metrics_block *tm) static bool tcp_metric_locked(struct tcp_metrics_block *tm, enum tcp_metric_index idx) { - return tm->tcpm_lock & (1 << idx); + /* Paired with WRITE_ONCE() in tcpm_suck_dst() */ + return READ_ONCE(tm->tcpm_lock) & (1 << idx); } static u32 tcp_metric_get(struct tcp_metrics_block *tm, @@ -110,7 +111,8 @@ static void tcpm_suck_dst(struct tcp_metrics_block *tm, val |= 1 << TCP_METRIC_CWND; if (dst_metric_locked(dst, RTAX_REORDERING)) val |= 1 << TCP_METRIC_REORDERING; - tm->tcpm_lock = val; + /* Paired with READ_ONCE() in tcp_metric_locked() */ + WRITE_ONCE(tm->tcpm_lock, val); msval = dst_metric_raw(dst, RTAX_RTT); tm->tcpm_vals[TCP_METRIC_RTT] = msval * USEC_PER_MSEC; -- 2.40.1