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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 31F79C433FE for ; Tue, 19 Oct 2021 10:19:08 +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 EADBB60F59 for ; Tue, 19 Oct 2021 10:19:07 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org EADBB60F59 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]:58788 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1mcmD4-0002Ak-Vk for qemu-devel@archiver.kernel.org; Tue, 19 Oct 2021 06:19:06 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:35890) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mcmA8-0006gi-Ae for qemu-devel@nongnu.org; Tue, 19 Oct 2021 06:16:06 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:24708) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mcmA6-00013b-9K for qemu-devel@nongnu.org; Tue, 19 Oct 2021 06:16:03 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1634638561; 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=jRkXrjMVNpvQyAqoNkhR4bpQh8KpptrPXV7JcFJhA4w=; b=c8SNX5wrG37wW/0U8Ib+tL98KL6iEyHaIdZ+6zC0N1knUoYN6KP5tuMMxidxAWd8yEaV76 kB1pnUMwhG2hO6krg8C4bubm5mUdAnYJrZpSUJ31mFtlvi2m4w1v4eyqJLt7pVim2DnowP dfixc+kgcfvoM6JWcSsBEfeDVIAmAkI= 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-6-Q58R22ZnPXeIDU0Mo8FKEw-1; Tue, 19 Oct 2021 06:16:00 -0400 X-MC-Unique: Q58R22ZnPXeIDU0Mo8FKEw-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 248E7804B9E; Tue, 19 Oct 2021 10:15:59 +0000 (UTC) Received: from localhost (unknown [10.39.195.161]) by smtp.corp.redhat.com (Postfix) with ESMTP id AE04C607A4; Tue, 19 Oct 2021 10:15:25 +0000 (UTC) Date: Tue, 19 Oct 2021 11:15:24 +0100 From: Stefan Hajnoczi To: Raphael Norwitz Subject: Re: [PATCH v5] Prevent vhost-user-blk-test hang Message-ID: References: <20210927171651.1433-1-raphael.norwitz@nutanix.com> MIME-Version: 1.0 In-Reply-To: <20210927171651.1433-1-raphael.norwitz@nutanix.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=stefanha@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="P+ennTgziamRRv+v" Content-Disposition: inline Received-SPF: pass client-ip=170.10.133.124; envelope-from=stefanha@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -28 X-Spam_score: -2.9 X-Spam_bar: -- X-Spam_report: (-2.9 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.049, 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" , "pbonzini@redhat.com" , "eblake@redhat.com" , "sgarzare@redhat.com" Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" --P+ennTgziamRRv+v Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, Sep 27, 2021 at 05:17:01PM +0000, Raphael Norwitz wrote: > In the vhost-user-blk-test, as of now there is nothing stoping > 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]. >=20 > This change makes the storage-daemon notify the vhost-user-blk-test > that it is fully initialized and ready to handle client connections by > creating a pidfile on initialiation. This ensures that the storage-daemon > backend won't miss vhost-user messages and thereby resolves the hang. >=20 > [1] https://lore.kernel.org/qemu-devel/CAFEAcA8kYpz9LiPNxnWJAPSjc=3Dnv532= bEdyfynaBeMeohqBp3A@mail.gmail.com/ The following hack triggers the hang. The stack traces match what Peter posted in the thread linked above. I'll take a closer look. --- diff --git a/storage-daemon/qemu-storage-daemon.c b/storage-daemon/qemu-sto= rage-daemon.c index 10a1a33761..50c9caa1b2 100644 --- a/storage-daemon/qemu-storage-daemon.c +++ b/storage-daemon/qemu-storage-daemon.c @@ -316,6 +316,8 @@ int main(int argc, char *argv[]) signal(SIGPIPE, SIG_IGN); #endif + sleep(5); + error_init(argv[0]); qemu_init_exec_dir(argv[0]); os_setup_signal_handling(); --P+ennTgziamRRv+v Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEEhpWov9P5fNqsNXdanKSrs4Grc8gFAmFumrwACgkQnKSrs4Gr c8jKAwf/aLsZiNXghDdr1zC+3FzJ/U6NNeIjOAEZ+ZdQzYSQX4EFGDvKBmr2rMtU Jf/c1ukhbbldof2z1NaqNiVWk4ChamQY667fG0gNSCOPkjfGzGZSdjRva8bwqZnq vBuElFxRF3AsFEcSEnCvbjppWH/rsSm3Q/qo7a5/yGIZkgsNYtqKdkazth32r+jx 9pjKAZbFdfT0zFUN9ava7SmMJZTbDd5R3NDKCy3lnzeYb3wMAq2PtVUHMbktoN4J GyxqAHpBkVUiXnjNq62Lje6Sj2EN2ZBvCK8C5J1H8DgPcrwxDJcw0rXj7f3icacR D7X+Jt6fqJNBZ6lUyNTSwHgJ6TGs+g== =nFmE -----END PGP SIGNATURE----- --P+ennTgziamRRv+v--