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=-12.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 71838C433ED for ; Wed, 19 May 2021 21:56:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5421C611BD for ; Wed, 19 May 2021 21:56:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229898AbhESV50 (ORCPT ); Wed, 19 May 2021 17:57:26 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58692 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229508AbhESV50 (ORCPT ); Wed, 19 May 2021 17:57:26 -0400 Received: from mail-il1-x136.google.com (mail-il1-x136.google.com [IPv6:2607:f8b0:4864:20::136]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id EA4A8C061574; Wed, 19 May 2021 14:56:04 -0700 (PDT) Received: by mail-il1-x136.google.com with SMTP id h6so13500343ila.7; Wed, 19 May 2021 14:56:04 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:message-id:in-reply-to:references:subject :mime-version:content-transfer-encoding; bh=5mRkprA2tLjeO7o2uum3+MPJOgOznrRqFoN+MMN+W3U=; b=oGpmT6cMlA4DduTCP1KUDlYrcARx7YnECdcSoVqW47RWPvHBNsOCMjubk0f9iQrXbV FvuF5F96eP5qZUyl+tCg5EFdt2ikK84WKhrkguJCw8nhjHssSo+huzY/GC4K2K59zxCP eQ+vxPRB/MXKFDPMmzgCRblI+ORhYE8egEUlZuKko691vR4/fPJA8BJLYByQRfxSmLwR NnMqqKndr+A8nkA4Pdwxf7aSQJD2VwiJr7slUYOmftUeUJxJVT4rn2YPesS94LD3EYxn emYyjuvAfcAdCvS6ECaTBcQrBCRU7UTrxk0Ve8YdSQaa4ZrdeeB2tL05OS8X+Kk0kghj t3XQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:message-id:in-reply-to :references:subject:mime-version:content-transfer-encoding; bh=5mRkprA2tLjeO7o2uum3+MPJOgOznrRqFoN+MMN+W3U=; b=givDitadHvqSdIgXSLDRwLr0O9qFFtdBwRdGr7013vNBJ6DNnuYV2xdxsKVUAP7szC yufcwSJbLmsyoasgLchdeOGnG201qt42D5zylkGCSBfKiQCdI9TgG47yP8qzhAcLls/e Oaut/NG9u784ninnxXgRuoZN7EKkzadx30FQN6ClNq4fwQ+qDGVxSQoqoLBH4Qg7lg68 EQBNcr8VWehcytSKLMJkDPR/i1j4k1iA6Mbk0ZSuuw/dYYQIHZH00N/fUAPsebUnKn28 henWWIitvU/RntECXhGiafpYc/psyGnEnQnc97k0P+/7LsSxOJ6+2nUM5brm9n2M+1n9 ECPw== X-Gm-Message-State: AOAM532GjIZFxgq65bwTmDDcy096unHdd48ywpqScpYmUmxy1VEmnvOg sSS6K2Hs2EMHWEhsFNoYdLY= X-Google-Smtp-Source: ABdhPJzfPJkKVERjY0feox9i8bBQGEGd5ezJAF/fXd+Ht8LHIEcfl/Jefcp9Y23ThCVvsqjfp5msLg== X-Received: by 2002:a92:c8d2:: with SMTP id c18mr1246773ilq.54.1621461364344; Wed, 19 May 2021 14:56:04 -0700 (PDT) Received: from localhost ([172.242.244.146]) by smtp.gmail.com with ESMTPSA id d5sm696409ilf.55.2021.05.19.14.56.03 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 19 May 2021 14:56:03 -0700 (PDT) Date: Wed, 19 May 2021 14:55:56 -0700 From: John Fastabend To: Cong Wang , netdev@vger.kernel.org Cc: bpf@vger.kernel.org, Cong Wang , Jiang Wang , John Fastabend , Daniel Borkmann , Jakub Sitnicki , Lorenz Bauer Message-ID: <60a5896ca080d_2aaa720821@john-XPS-13-9370.notmuch> In-Reply-To: <20210519204132.107247-1-xiyou.wangcong@gmail.com> References: <20210519204132.107247-1-xiyou.wangcong@gmail.com> Subject: RE: [Patch bpf] selftests/bpf: Retry for EAGAIN in udp_redir_to_connected() Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Cong Wang wrote: > From: Cong Wang > > We use non-blocking sockets for testing sockmap redirections, > and got some random EAGAIN errors from UDP tests. > > There is no guarantee the packet would be immediately available > to receive as soon as it is sent out, even on the local host. > For UDP, this is especially true because it does not lock the > sock during BH (unlike the TCP path). This is probably why we > only saw this error in UDP cases. > > No matter how hard we try to make the queue empty check accurate, > it is always possible for recvmsg() to beat ->sk_data_ready(). > Therefore, we should just retry in case of EAGAIN. > > Fixes: d6378af615275 ("selftests/bpf: Add a test case for udp sockmap") > Reported-by: Jiang Wang > Cc: John Fastabend > Cc: Daniel Borkmann > Cc: Jakub Sitnicki > Cc: Lorenz Bauer > Signed-off-by: Cong Wang > --- > tools/testing/selftests/bpf/prog_tests/sockmap_listen.c | 6 +++++- > 1 file changed, 5 insertions(+), 1 deletion(-) > > diff --git a/tools/testing/selftests/bpf/prog_tests/sockmap_listen.c b/tools/testing/selftests/bpf/prog_tests/sockmap_listen.c > index 648d9ae898d2..b1ed182c4720 100644 > --- a/tools/testing/selftests/bpf/prog_tests/sockmap_listen.c > +++ b/tools/testing/selftests/bpf/prog_tests/sockmap_listen.c > @@ -1686,9 +1686,13 @@ static void udp_redir_to_connected(int family, int sotype, int sock_mapfd, > if (pass != 1) > FAIL("%s: want pass count 1, have %d", log_prefix, pass); > > +again: > n = read(mode == REDIR_INGRESS ? p0 : c0, &b, 1); > - if (n < 0) > + if (n < 0) { > + if (errno == EAGAIN) > + goto again; > FAIL_ERRNO("%s: read", log_prefix); Needs a counter and abort logic we don't want to loop forever in the case the packet is lost. > + } > if (n == 0) > FAIL("%s: incomplete read", log_prefix); > > -- > 2.25.1 >