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=-8.1 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, 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 450CAC33C99 for ; Tue, 7 Jan 2020 11:32:31 +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 13A1C2077B for ; Tue, 7 Jan 2020 11:32:31 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="ib/AaEQm" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 13A1C2077B Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:46942 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1ion64-00020V-MO for qemu-devel@archiver.kernel.org; Tue, 07 Jan 2020 06:32:28 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:38925) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iomvd-0000FF-EC for qemu-devel@nongnu.org; Tue, 07 Jan 2020 06:21:42 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1iomvc-0004mC-6Y for qemu-devel@nongnu.org; Tue, 07 Jan 2020 06:21:41 -0500 Received: from us-smtp-delivery-1.mimecast.com ([205.139.110.120]:35296 helo=us-smtp-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1iomvc-0004ly-34 for qemu-devel@nongnu.org; Tue, 07 Jan 2020 06:21:40 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1578396099; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=XRU1fbeHj2mEmmyk9undtp1vHtmrOVjpgS4wUuIFOk4=; b=ib/AaEQmX4vkdnUF89f7+7TkH3vk6L+SfocV9oEyq1caH5fjYEkWvzzdnZ2nj4lA7DaSFS q81z6SLQa5aRNnoHv9K0uB6NiG+HNW39OlXp0bTU02FEDOdibSnyIMWmrgkd+rR3d6YXGu BX+JeqyaxuR//P8GQJyp58fLF8SIL2A= 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-98-wbaofb6TOmydSx9Y1xbDaQ-1; Tue, 07 Jan 2020 06:21:38 -0500 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 94629801E72 for ; Tue, 7 Jan 2020 11:21:37 +0000 (UTC) Received: from work-vm (ovpn-117-52.ams2.redhat.com [10.36.117.52]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 64EF185EE6; Tue, 7 Jan 2020 11:21:36 +0000 (UTC) Date: Tue, 7 Jan 2020 11:21:33 +0000 From: "Dr. David Alan Gilbert" To: Juan Quintela Subject: Re: [PATCH v2 2/3] migration: Make sure that we don't call write() in case of error Message-ID: <20200107112133.GC2732@work-vm> References: <20200107104914.1814-1-quintela@redhat.com> <20200107104914.1814-3-quintela@redhat.com> MIME-Version: 1.0 In-Reply-To: <20200107104914.1814-3-quintela@redhat.com> User-Agent: Mutt/1.13.0 (2019-11-30) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-MC-Unique: wbaofb6TOmydSx9Y1xbDaQ-1 X-Mimecast-Spam-Score: 0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: quoted-printable Content-Disposition: inline X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 205.139.110.120 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: Laurent Vivier , Paolo Bonzini , Thomas Huth , qemu-devel@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" * Juan Quintela (quintela@redhat.com) wrote: > If we are exiting due to an error/finish/.... Just don't try to even > touch the channel with one IO operation. >=20 > Signed-off-by: Juan Quintela > Reviewed-by: Dr. David Alan Gilbert > Signed-off-by: Juan Quintela > --- > migration/ram.c | 25 +++++++++++++++++++++++++ > 1 file changed, 25 insertions(+) >=20 > diff --git a/migration/ram.c b/migration/ram.c > index 96feb4062c..6e678dbd2e 100644 > --- a/migration/ram.c > +++ b/migration/ram.c > @@ -900,6 +900,12 @@ struct { > uint64_t packet_num; > /* send channels ready */ > QemuSemaphore channels_ready; > + /* > + * Have we already run terminate threads. There is a race when it > + * happens that we got one error while we are exiting. > + * We will use atomic operations. Only valid values are 0 and 1. > + */ > + int exiting; > } *multifd_send_state; > =20 > /* > @@ -928,6 +934,10 @@ static int multifd_send_pages(RAMState *rs) > MultiFDPages_t *pages =3D multifd_send_state->pages; > uint64_t transferred; > =20 > + if (atomic_read(&multifd_send_state->exiting)) { > + return -1; > + } > + > qemu_sem_wait(&multifd_send_state->channels_ready); > for (i =3D next_channel;; i =3D (i + 1) % migrate_multifd_channels()= ) { > p =3D &multifd_send_state->params[i]; > @@ -1009,6 +1019,16 @@ static void multifd_send_terminate_threads(Error *= err) > } > } > =20 > + /* > + * We don't want to exit each threads twice. Depending on where > + * we get the error, or if there are two independent errors in two > + * threads at the same time, we can end calling this function > + * twice. > + */ Yeh that makes it cleaer. Thanks > + if (atomic_xchg(&multifd_send_state->exiting, 1)) { > + return; > + } > + > for (i =3D 0; i < migrate_multifd_channels(); i++) { > MultiFDSendParams *p =3D &multifd_send_state->params[i]; > =20 > @@ -1118,6 +1138,10 @@ static void *multifd_send_thread(void *opaque) > =20 > while (true) { > qemu_sem_wait(&p->sem); > + > + if (atomic_read(&multifd_send_state->exiting)) { > + break; > + } > qemu_mutex_lock(&p->mutex); > =20 > if (p->pending_job) { > @@ -1224,6 +1248,7 @@ int multifd_save_setup(void) > multifd_send_state->params =3D g_new0(MultiFDSendParams, thread_coun= t); > multifd_send_state->pages =3D multifd_pages_init(page_count); > qemu_sem_init(&multifd_send_state->channels_ready, 0); > + atomic_set(&multifd_send_state->exiting, 0); > =20 > for (i =3D 0; i < thread_count; i++) { > MultiFDSendParams *p =3D &multifd_send_state->params[i]; > --=20 > 2.24.1 >=20 -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK