From patchwork Mon Nov 9 13:06:20 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Menglong Dong X-Patchwork-Id: 1396740 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming-netdev@ozlabs.org Delivered-To: patchwork-incoming-netdev@ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org (client-ip=23.128.96.18; helo=vger.kernel.org; envelope-from=netdev-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256 header.s=20161025 header.b=sT3nKO/o; dkim-atps=neutral Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by ozlabs.org (Postfix) with ESMTP id 4CVB913S18z9sSs for ; Tue, 10 Nov 2020 00:07:01 +1100 (AEDT) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730474AbgKING7 (ORCPT ); Mon, 9 Nov 2020 08:06:59 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50332 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731186AbgKING6 (ORCPT ); Mon, 9 Nov 2020 08:06:58 -0500 Received: from mail-pf1-x443.google.com (mail-pf1-x443.google.com [IPv6:2607:f8b0:4864:20::443]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C0BC1C0613CF; Mon, 9 Nov 2020 05:06:57 -0800 (PST) Received: by mail-pf1-x443.google.com with SMTP id w6so2615058pfu.1; Mon, 09 Nov 2020 05:06:57 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=message-id:from:to:cc:subject:date; bh=pv/qcPPzxY24BJv/TEpfoqjXaGRaaqqNFfUeBE2/vdI=; b=sT3nKO/oUVfm1r6qUVlx1wsZeOwbzS5aKSfpGj0Z7RVxxARSTKPn62yeSyDj5wLZ4r SzsJX7bXPAHAnpL87g/XKHuUAW6Ei5n2yfkmx/BKKtY4579berHzvRlUb9LnN4zKCrbo eKY5UXRUVP2Ku3N1mNY1fW1es+A8LpekORFMxoxkMYzSSHWWtx1UsvxH8Cy17175XzKo SkOsE7Vag79J3/+/ezNwWQH/JCSMCuACPMN1/AM1PYJcK7KhXr1EkJeMXh0yy0gxJQXO 3L0u4k7SixloDgV1Bfq2ysVFo/plNGRuGz30g7VlQ8J8Dl7qV7VFglCVhf4AvCU5AXjI cZMA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:message-id:from:to:cc:subject:date; bh=pv/qcPPzxY24BJv/TEpfoqjXaGRaaqqNFfUeBE2/vdI=; b=at32OKK5VyvPKAzwnsn8zJc6LjtKByLCJqx/kEs8HJ0/jfxKXDc2yzTPmHmEJn25+S OenZg49uIIhyfKzn/pPH08dbE4rkuchs2duJlWaCF0uKJEEMU8IYdPg8ENPyZ8ZBBYXw inBzkUF0hofatl0v1BxJ7iokHMjb5v23NDDRTVdOiG+8/wYfXygLVzmCH5jgCGfxJqkr 2vX8Yykc8WSdDC6EszHxKwbkbDvSAtPTpW2l3t08FhfRxLhsuQEU68D45W1EvKFnyidV tl6LhPPElWCz8328B95y0yVVBC+R20yJ4VtmkLwkiUyd7zsi2XBGuA1m9clG1gVGr+1U HFzg== X-Gm-Message-State: AOAM531q5DKek3vWIbZ/0n9Xcq15LZ3gdM/vUbfv0BHU64x4ciby1b46 sDr40SMmsGq2OjYWbnfD9U8= X-Google-Smtp-Source: ABdhPJwD4jwkOUq/fxk5ZZIs+ZhQ+9KL97Y1VfG/9OPmSl6RAtuihPW0tL0U8O5xLmZMdq02ZvvZOA== X-Received: by 2002:a17:90b:386:: with SMTP id ga6mr3765316pjb.209.1604927217360; Mon, 09 Nov 2020 05:06:57 -0800 (PST) Received: from localhost.localdomain ([154.93.3.113]) by smtp.gmail.com with ESMTPSA id t18sm8246920pjs.56.2020.11.09.05.06.55 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Mon, 09 Nov 2020 05:06:56 -0800 (PST) Message-ID: <5fa93ef0.1c69fb81.bff98.2afc@mx.google.com> X-Google-Original-Message-ID: <1604927180-63394-1-git-send-email---global> From: menglong8.dong@gmail.com X-Google-Original-From: --global To: edumazet@google.com Cc: davem@davemloft.net, kuznet@ms2.inr.ac.ru, yoshfuji@linux-ipv6.org, kuba@kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Menglong Dong Subject: [PATCH] net: tcp: ratelimit warnings in tcp_recvmsg Date: Mon, 9 Nov 2020 08:06:20 -0500 X-Mailer: git-send-email 2.7.4 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org From: Menglong Dong 'before(*seq, TCP_SKB_CB(skb)->seq) == true' means that one or more skbs are lost somehow. Once this happen, it seems that it will never recover automatically. As a result, a warning will be printed and a '-EAGAIN' will be returned in non-block mode. As a general suituation, users call 'poll' on a socket and then receive skbs with 'recv' in non-block mode. This mode will make every arriving skb of the socket trigger a warning. Plenty of skbs will cause high rate of kernel log. Besides, WARN is for indicating kernel bugs only and should not be user-triggable. Replace it with 'net_warn_ratelimited' here. Signed-off-by: Menglong Dong --- net/ipv4/tcp.c | 17 ++++++++++------- 1 file changed, 10 insertions(+), 7 deletions(-) diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index b2bc3d7fe9e8..5e38dfd03036 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -2093,11 +2093,12 @@ int tcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int nonblock, /* Now that we have two receive queues this * shouldn't happen. */ - if (WARN(before(*seq, TCP_SKB_CB(skb)->seq), - "TCP recvmsg seq # bug: copied %X, seq %X, rcvnxt %X, fl %X\n", - *seq, TCP_SKB_CB(skb)->seq, tp->rcv_nxt, - flags)) + if (unlikely(before(*seq, TCP_SKB_CB(skb)->seq))) { + net_warn_ratelimited("TCP recvmsg seq # bug: copied %X, seq %X, rcvnxt %X, fl %X\n", + *seq, TCP_SKB_CB(skb)->seq, tp->rcv_nxt, + flags); break; + } offset = *seq - TCP_SKB_CB(skb)->seq; if (unlikely(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN)) { @@ -2108,9 +2109,11 @@ int tcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int nonblock, goto found_ok_skb; if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN) goto found_fin_ok; - WARN(!(flags & MSG_PEEK), - "TCP recvmsg seq # bug 2: copied %X, seq %X, rcvnxt %X, fl %X\n", - *seq, TCP_SKB_CB(skb)->seq, tp->rcv_nxt, flags); + + if (!(flags & MSG_PEEK)) + net_warn_ratelimited("TCP recvmsg seq # bug 2: copied %X, seq %X, rcvnxt %X, fl %X\n", + *seq, TCP_SKB_CB(skb)->seq, tp->rcv_nxt, + flags); } /* Well, if we have backlog, try to process it now yet. */