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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,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 96C55C3A5A4 for ; Fri, 23 Aug 2019 16:19:25 +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 72A6722CEC for ; Fri, 23 Aug 2019 16:19:25 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 72A6722CEC 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]:59098 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1i1CHc-0002k8-KX for qemu-devel@archiver.kernel.org; Fri, 23 Aug 2019 12:19:24 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:43669) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1i1CGU-0002JK-Cd for qemu-devel@nongnu.org; Fri, 23 Aug 2019 12:18:15 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1i1CGS-0006He-O7 for qemu-devel@nongnu.org; Fri, 23 Aug 2019 12:18:14 -0400 Received: from mx1.redhat.com ([209.132.183.28]:45540) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1i1CGS-0006Gy-GM for qemu-devel@nongnu.org; Fri, 23 Aug 2019 12:18:12 -0400 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 mx1.redhat.com (Postfix) with ESMTPS id 5152D2A09C2; Fri, 23 Aug 2019 16:18:11 +0000 (UTC) Received: from work-vm (ovpn-117-244.ams2.redhat.com [10.36.117.244]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 426B16092D; Fri, 23 Aug 2019 16:18:10 +0000 (UTC) Date: Fri, 23 Aug 2019 17:18:07 +0100 From: "Dr. David Alan Gilbert" To: Wei Yang Message-ID: <20190823161807.GP2784@work-vm> References: <20190621142739.23703-1-richardw.yang@linux.intel.com> <20190819112632.GA2765@work-vm> <20190819140828.otv7vq5lahvquczl@master> <20190823152916.GN2784@work-vm> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190823152916.GN2784@work-vm> User-Agent: Mutt/1.12.1 (2019-06-15) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.38]); Fri, 23 Aug 2019 16:18:11 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: Re: [Qemu-devel] [PATCH] migrtion: define MigrationState/MigrationIncomingState.state as MigrationStatus 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: quintela@redhat.com, Wei Yang , qemu-devel@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" * Dr. David Alan Gilbert (dgilbert@redhat.com) wrote: > * Wei Yang (richard.weiyang@gmail.com) wrote: > > On Mon, Aug 19, 2019 at 12:26:32PM +0100, Dr. David Alan Gilbert wrote: > > >* Wei Yang (richardw.yang@linux.intel.com) wrote: > > >> No functional change. Add default case to fix warning. > > > > > >I think the problem with this is that migrate_set_state uses an > > >atomic_cmpxchg and so we have to be careful that the type we use > > >is compatible with that. > > >MigrationStatus is an enum and I think compilers are allowed to > > >choose the types of that; so I'm not sure we're guaranteed > > >that an enum is always OK for the atomic_cmpxchg, and if it is > > > > Took a look into the definition of atomic_cmpxchg, which finally calls > > > > * __atomic_compare_exchange_n for c++11 > > * __sync_val_compare_and_swap > > > > Both of them take two pointers to compare and exchange its content. > > > > Per C99 standard, http://www.open-std.org/JTC1/SC22/WG14/www/docs/n1256.pdf, > > it mentioned: > > > > Each enumerated type shall be compatible with char, a signed integer type, > > or an unsigned integer type. The choice of type is implementation-defined, > > but shall be capable of representing the values of all the members of the > > enumeration. > > > > Based on this, I think atomic_cmpxchg should work fine with enum. > > Hmm OK, but I'd need you to test n some 32bit and other comp=ilers etc; > make sure it works on 32bit, clang, gcc, 32bit ARM etc - because > otherwise I'm going to have to worry about checking all those. Actually since QEMU is defined to be C99, the test is to check with some C99 compilers; eblake assures me that in theory C11 should be OK, but C99 and our atomics are more of an interesting question. Dave > Dave > > > >then we also might have to make the old_state and new_state > > >variables match. > > > > > > > You are right. > > >Dave > > > > > >> Signed-off-by: Wei Yang > > >> --- > > >> migration/migration.c | 8 +++++++- > > >> migration/migration.h | 6 +++--- > > >> 2 files changed, 10 insertions(+), 4 deletions(-) > > >> > > >> diff --git a/migration/migration.c b/migration/migration.c > > >> index 2865ae3fa9..0fd2364961 100644 > > >> --- a/migration/migration.c > > >> +++ b/migration/migration.c > > >> @@ -946,6 +946,8 @@ static void fill_source_migration_info(MigrationInfo *info) > > >> case MIGRATION_STATUS_CANCELLED: > > >> info->has_status = true; > > >> break; > > >> + default: > > >> + return; > > >> } > > >> info->status = s->state; > > >> } > > >> @@ -1054,6 +1056,8 @@ static void fill_destination_migration_info(MigrationInfo *info) > > >> info->has_status = true; > > >> fill_destination_postcopy_migration_info(info); > > >> break; > > >> + default: > > >> + return; > > >> } > > >> info->status = mis->state; > > >> } > > >> @@ -1446,7 +1450,7 @@ void qmp_migrate_start_postcopy(Error **errp) > > >> > > >> /* shared migration helpers */ > > >> > > >> -void migrate_set_state(int *state, int old_state, int new_state) > > >> +void migrate_set_state(MigrationStatus *state, int old_state, int new_state) > > >> { > > >> assert(new_state < MIGRATION_STATUS__MAX); > > >> if (atomic_cmpxchg(state, old_state, new_state) == old_state) { > > >> @@ -1683,6 +1687,8 @@ bool migration_is_idle(void) > > >> return false; > > >> case MIGRATION_STATUS__MAX: > > >> g_assert_not_reached(); > > >> + default: > > >> + g_assert_not_reached(); > > >> } > > >> > > >> return false; > > >> diff --git a/migration/migration.h b/migration/migration.h > > >> index 5e8f09c6db..418ee00053 100644 > > >> --- a/migration/migration.h > > >> +++ b/migration/migration.h > > >> @@ -65,7 +65,7 @@ struct MigrationIncomingState { > > >> > > >> QEMUBH *bh; > > >> > > >> - int state; > > >> + MigrationStatus state; > > >> > > >> bool have_colo_incoming_thread; > > >> QemuThread colo_incoming_thread; > > >> @@ -151,7 +151,7 @@ struct MigrationState > > >> /* params from 'migrate-set-parameters' */ > > >> MigrationParameters parameters; > > >> > > >> - int state; > > >> + MigrationStatus state; > > >> > > >> /* State related to return path */ > > >> struct { > > >> @@ -234,7 +234,7 @@ struct MigrationState > > >> bool decompress_error_check; > > >> }; > > >> > > >> -void migrate_set_state(int *state, int old_state, int new_state); > > >> +void migrate_set_state(MigrationStatus *state, int old_state, int new_state); > > >> > > >> void migration_fd_process_incoming(QEMUFile *f); > > >> void migration_ioc_process_incoming(QIOChannel *ioc, Error **errp); > > >> -- > > >> 2.19.1 > > >> > > >-- > > >Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK > > > > -- > > Wei Yang > > Help you, Help me > -- > Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK