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=-15.1 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham 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 D6EDAC432BE for ; Fri, 27 Aug 2021 18:57:21 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 435E960EBA for ; Fri, 27 Aug 2021 18:57:21 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 435E960EBA Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=nongnu.org Received: from localhost ([::1]:60092 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1mJh2W-0007UF-7z for qemu-devel@archiver.kernel.org; Fri, 27 Aug 2021 14:57:20 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:39496) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mJh1G-0006lc-Ve for qemu-devel@nongnu.org; Fri, 27 Aug 2021 14:56:02 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:49415) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mJh1C-0005kb-2Q for qemu-devel@nongnu.org; Fri, 27 Aug 2021 14:56:02 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1630090556; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=GuaaiI7ps7pC947Eco058fNG/MWx2GVrMdzZDRHBYVc=; b=NaPSZaabmY0N2+OImZ6+4k8Nb18ydguM+b8GUkuYI3eXKQbb30W4MeAKL0lJCLGWlLPyzT zNPev/TVUYjiZpJvCDdlY38iyi/zccGnQy5DwvpYzV4fU4jj/tWD2z7uCoUuVMYhQLFNq/ UTAnsV6FJrt3XRUFa2N651e2l6l11Ro= 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-146-4b86KLE4PD621fMLn-RLEA-1; Fri, 27 Aug 2021 14:55:53 -0400 X-MC-Unique: 4b86KLE4PD621fMLn-RLEA-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id F15BD801B3D; Fri, 27 Aug 2021 18:55:51 +0000 (UTC) Received: from redhat.com (ovpn-112-96.phx2.redhat.com [10.3.112.96]) by smtp.corp.redhat.com (Postfix) with ESMTPS id DA3AD1017CCB; Fri, 27 Aug 2021 18:55:42 +0000 (UTC) Date: Fri, 27 Aug 2021 13:55:41 -0500 From: "eblake@redhat.com" To: Raphael Norwitz Subject: Re: [PATCH 2/2] Prevent vhost-user-blk-test hang Message-ID: <20210827185541.ehmhgoznavtyogfc@redhat.com> References: <20210827164954.13951-1-raphael.norwitz@nutanix.com> <20210827164954.13951-2-raphael.norwitz@nutanix.com> MIME-Version: 1.0 In-Reply-To: <20210827164954.13951-2-raphael.norwitz@nutanix.com> User-Agent: NeoMutt/20210205-739-420e15 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=eblake@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Received-SPF: pass client-ip=170.10.133.124; envelope-from=eblake@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -34 X-Spam_score: -3.5 X-Spam_bar: --- X-Spam_report: (-3.5 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.743, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "peter.maydell@linaro.org" , "mst@redhat.com" , "qemu-devel@nongnu.org" , "mreitz@redhat.com" , "stefanha@redhat.com" , "pbonzini@redhat.com" , "sgarzare@redhat.com" Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Fri, Aug 27, 2021 at 04:50:47PM +0000, Raphael Norwitz wrote: > In the vhost-user-blk-test, as of now there is nothing stoping stopping > vhost-user-blk in QEMU writing to the socket right after forking off the > storage daemon before it has a chance to come up properly, leaving the > test hanging forever. This intermittently hanging test has caused QEMU > automation failures reported multiple times on the mailing list [1]. > > This change makes the storage-daemon notify the vhost-user-blk-test > that it is fully initialized and ready to handle client connections via > a pipefd before allowing the test to proceed. This ensures that the > storage-daemon backend won't miss vhost-user messages and thereby > resolves the hang. As I said on patch 1, I think the proper fix here is to utilize the --pidfile option. > > [1] https://lore.kernel.org/qemu-devel/CAFEAcA8kYpz9LiPNxnWJAPSjc=nv532bEdyfynaBeMeohqBp3A@mail.gmail.com/ > > Signed-off-by: Raphael Norwitz > --- > tests/qtest/vhost-user-blk-test.c | 33 ++++++++++++++++++++++++++++--- > 1 file changed, 30 insertions(+), 3 deletions(-) > > diff --git a/tests/qtest/vhost-user-blk-test.c b/tests/qtest/vhost-user-blk-test.c > index 6f108a1b62..b62af449df 100644 > --- a/tests/qtest/vhost-user-blk-test.c > +++ b/tests/qtest/vhost-user-blk-test.c > @@ -21,6 +21,8 @@ > #include "libqos/vhost-user-blk.h" > #include "libqos/libqos-pc.h" > > +const char *daemon_msg = "Block exports setup\n"; > + > #define TEST_IMAGE_SIZE (64 * 1024 * 1024) > #define QVIRTIO_BLK_TIMEOUT_US (30 * 1000 * 1000) > #define PCI_SLOT_HP 0x06 > @@ -885,7 +887,8 @@ static void start_vhost_user_blk(GString *cmd_line, int vus_instances, > int num_queues) > { > const char *vhost_user_blk_bin = qtest_qemu_storage_daemon_binary(); > - int i; > + int i, err, pipe_fds[2]; > + char buf[32] = {0}; > gchar *img_path; > GString *storage_daemon_command = g_string_new(NULL); > QemuStorageDaemonState *qsd; > @@ -898,6 +901,12 @@ static void start_vhost_user_blk(GString *cmd_line, int vus_instances, > " -object memory-backend-memfd,id=mem,size=256M,share=on " > " -M memory-backend=mem -m 256M "); > > + err = pipe(pipe_fds); > + if (err != 0) { > + fprintf(stderr, "start_vhost_user_blk: pipe() failed %m\n"); > + abort(); > + } Instead of setting up a pipe()... > + > for (i = 0; i < vus_instances; i++) { > int fd; > char *sock_path = create_listen_socket(&fd); > @@ -914,22 +923,40 @@ static void start_vhost_user_blk(GString *cmd_line, int vus_instances, > i + 1, sock_path); > } > > + g_string_append_printf(storage_daemon_command, "--printset"); ...change this to request the --pidfile option... > + > g_test_message("starting vhost-user backend: %s", > storage_daemon_command->str); > + > pid_t pid = fork(); > if (pid == 0) { > + close(pipe_fds[0]); > + > /* > * Close standard file descriptors so tap-driver.pl pipe detects when > * our parent terminates. > */ > close(0); > - close(1); > open("/dev/null", O_RDONLY); > - open("/dev/null", O_WRONLY); > + close(1); > + dup2(pipe_fds[1], 1); > > execlp("/bin/sh", "sh", "-c", storage_daemon_command->str, NULL); > exit(1); > } > + > + close(pipe_fds[1]); > + > + err = read(pipe_fds[0], buf, 20); > + if (err < 0) { > + fprintf(stderr, "Failed to read from storage-daemon pipe %m\n"); > + abort(); > + } else if (strcmp(buf, daemon_msg) != 0) { > + fprintf(stderr, "qemu-storage-daemon did not write expected messaage " > + "to the pipe. Total bytes read: %d. Got: %s\n", err, buf); > + abort(); > + } ...and instead of trying to read() from a pipe, you instead wait until the pid file exists. > + > g_string_free(storage_daemon_command, true); > > qsd = g_new(QemuStorageDaemonState, 1); > -- > 2.20.1 > -- Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3266 Virtualization: qemu.org | libvirt.org