From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on dcvr.yhbt.net X-Spam-Level: X-Spam-Status: No, score=-4.2 required=3.0 tests=AWL,BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,MAILING_LIST_MULTI, SPF_HELO_PASS,SPF_PASS shortcircuit=no autolearn=ham autolearn_force=no version=3.4.2 Received: from sourceware.org (server2.sourceware.org [IPv6:2620:52:3:1:0:246e:9693:128c]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by dcvr.yhbt.net (Postfix) with ESMTPS id 56AEA1F4B4 for ; Wed, 14 Oct 2020 17:57:45 +0000 (UTC) Received: from server2.sourceware.org (localhost [IPv6:::1]) by sourceware.org (Postfix) with ESMTP id 231153943417; Wed, 14 Oct 2020 17:57:44 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 231153943417 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sourceware.org; s=default; t=1602698264; bh=Kns03zBNHK9R/ZdWrPz4xzj/keSUSuW82L9CYSRmngc=; h=To:Subject:References:Date:In-Reply-To:List-Id:List-Unsubscribe: List-Archive:List-Post:List-Help:List-Subscribe:From:Reply-To:Cc: From; b=S/6hTGIOH9sCmVCdTHklBVKDu41yz1iTzhiN6OeFpOI1R/eBjw1uGyQTwiQ/m2+BN ea6qGscujt/mp8qlD5SM6PaEgUkXHkM+JSaNGBy/ISyv/yC0itxYX5OPAplnnYSIld 6m0R3JLz9/zxX3iD6biEltS9dD+Jj4/xCqfoUn/M= Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [63.128.21.124]) by sourceware.org (Postfix) with ESMTP id CA6263844013 for ; Wed, 14 Oct 2020 17:57:41 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.3.2 sourceware.org CA6263844013 Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-470-gOtuTpC0NuKoareHIVA8Qw-1; Wed, 14 Oct 2020 13:57:39 -0400 X-MC-Unique: gOtuTpC0NuKoareHIVA8Qw-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id D90251868414; Wed, 14 Oct 2020 17:57:37 +0000 (UTC) Received: from oldenburg2.str.redhat.com (ovpn-114-103.ams2.redhat.com [10.36.114.103]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 2F4A35D9CD; Wed, 14 Oct 2020 17:57:37 +0000 (UTC) To: Stefan Liebler via Libc-alpha Subject: Re: [PATCH 3/3] resolv: Handle transaction ID collisions in parallel queries (bug 26600) References: <55f9a2d387df8fae7d44275e2cf7dce8eccd120e.1599829382.git.fweimer@redhat.com> <87lfhgqx9u.fsf@oldenburg2.str.redhat.com> <180cdf95-e0cc-8c0d-1594-06a35a2012be@linux.ibm.com> Date: Wed, 14 Oct 2020 19:57:35 +0200 In-Reply-To: <180cdf95-e0cc-8c0d-1594-06a35a2012be@linux.ibm.com> (Stefan Liebler via Libc-alpha's message of "Wed, 14 Oct 2020 18:32:10 +0200") Message-ID: <87k0vsk7w0.fsf@oldenburg2.str.redhat.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.1 (gnu/linux) MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , From: Florian Weimer via Libc-alpha Reply-To: Florian Weimer Cc: Stefan Liebler Errors-To: libc-alpha-bounces@sourceware.org Sender: "Libc-alpha" * Stefan Liebler via Libc-alpha: > On 10/13/20 8:18 PM, Siddhesh Poyarekar wrote: >> On 9/11/20 6:35 PM, Florian Weimer via Libc-alpha wrote: > ... >> >> Test is also OK. >> >> Looks good to me. >> >> Thanks, >> Siddhesh >> > Hi Florian, > > I've recognized a test-fail for the new test > resolv/tst-resolv-txnid-collision (of course on s390x): > tst-resolv-txnid-collision.c:166: numeric comparison failure > left: 0 (0x0); from: ctx->server_index > right: 1 (0x1); from: previous_server_index > error: tst-resolv-txnid-collision.c:167: not true: previous_qtype != qtype > error: 2 test failures > (See attached tst-resolv-txnid-collision_20201014_174129_4983.log) > > So far, I've just run the test resolv/tst-resolv-txnid-collision with > --direct --verbose in a loop and collected the output (see attachements). Well, this is embarrassing. I will have to make the test more tolerant of packet reordering. Thanks for reporting this, I can (somewhat rarely) reproduce this, on an s390x system (under high load, I think). > It also happens that the test segfaults. > Here is one backtrace (also see attached > tst-resolv-txnid-collision_20201014_174533_4318.log): > (gdb) bt full > #0 0x0000000001001c28 in resolv_response_context_free (ctx=0x0) at > resolv_response_context_free.c:25 > No locals. > #1 0x00000000010017cc in response (ctx=0x3fffcf7cab8, b=0x3ffec000b60, > qname=0x3fffcf7cb72 "reorder-1-0.rcode-2.example.net", > qclass=, qtype=) at > tst-resolv-txnid-collision.c:204 > parsed = {rcode = 2, reorder = {true, false}} This should fix the crash at least, it's a concurrency bug in the test: diff --git a/resolv/tst-resolv-txnid-collision.c b/resolv/tst-resolv-txnid-collision.c index 611d3736..db9a52b6 100644 --- a/resolv/tst-resolv-txnid-collision.c +++ b/resolv/tst-resolv-txnid-collision.c @@ -309,6 +309,7 @@ do_test (void) ((struct resolv_redirect_config) { .response_callback = response, + .single_thread_udp = true, }); for (int rcode = 0; rcode <= 5; ++rcode) I doubt it will fix the other test failure, but I'm going to run the test over night with this test. Thanks, Florian -- Red Hat GmbH, https://de.redhat.com/ , Registered seat: Grasbrunn, Commercial register: Amtsgericht Muenchen, HRB 153243, Managing Directors: Charles Cachera, Brian Klemm, Laurie Krebs, Michael O'Neill