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 38DC8C3A5A2 for ; Fri, 23 Aug 2019 15:41:27 +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 1087D21019 for ; Fri, 23 Aug 2019 15:41:27 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1087D21019 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]:58430 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1i1Bgs-0002MY-AB for qemu-devel@archiver.kernel.org; Fri, 23 Aug 2019 11:41:26 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:60865) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1i1BVF-0006td-28 for qemu-devel@nongnu.org; Fri, 23 Aug 2019 11:29:27 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1i1BVB-0002Yr-0h for qemu-devel@nongnu.org; Fri, 23 Aug 2019 11:29:25 -0400 Received: from mx1.redhat.com ([209.132.183.28]:63174) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1i1BVA-0002Xg-P4 for qemu-devel@nongnu.org; Fri, 23 Aug 2019 11:29:20 -0400 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 mx1.redhat.com (Postfix) with ESMTPS id 960F0106E280; Fri, 23 Aug 2019 15:29:19 +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 8772310013D9; Fri, 23 Aug 2019 15:29:18 +0000 (UTC) Date: Fri, 23 Aug 2019 16:29:16 +0100 From: "Dr. David Alan Gilbert" To: Wei Yang Message-ID: <20190823152916.GN2784@work-vm> References: <20190621142739.23703-1-richardw.yang@linux.intel.com> <20190819112632.GA2765@work-vm> <20190819140828.otv7vq5lahvquczl@master> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190819140828.otv7vq5lahvquczl@master> User-Agent: Mutt/1.12.1 (2019-06-15) X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.6.2 (mx1.redhat.com [10.5.110.64]); Fri, 23 Aug 2019 15:29:19 +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" * 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. 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