From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:50218) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1elgvF-00009q-Cd for qemu-devel@nongnu.org; Tue, 13 Feb 2018 15:11:26 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1elgvA-0006Ok-DZ for qemu-devel@nongnu.org; Tue, 13 Feb 2018 15:11:25 -0500 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:57802 helo=mx1.redhat.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1elgvA-0006OR-8H for qemu-devel@nongnu.org; Tue, 13 Feb 2018 15:11:20 -0500 Date: Tue, 13 Feb 2018 20:11:00 +0000 From: "Dr. David Alan Gilbert" Message-ID: <20180213201059.GU2378@work-vm> References: <20180208103132.28452-1-peterx@redhat.com> <20180208103132.28452-28-peterx@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180208103132.28452-28-peterx@redhat.com> Subject: Re: [Qemu-devel] [PATCH v6 27/28] migration/qmp: add command migrate-pause List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Peter Xu Cc: qemu-devel@nongnu.org, Alexey Perevalov , "Daniel P . Berrange" , Juan Quintela , Andrea Arcangeli * Peter Xu (peterx@redhat.com) wrote: > It pauses an ongoing migration. Currently it only supports postcopy. > Note that this command will work on either side of the migration. > Basically when we trigger this on one side, it'll interrupt the other > side as well since the other side will get notified on the disconnect > event. > > However, it's still possible that the other side is not notified, for > example, when the network is totally broken, or due to some firewall > configuration changes. In that case, we will also need to run the same > command on the other side so both sides will go into the paused state. > > Signed-off-by: Peter Xu > --- > migration/migration.c | 27 +++++++++++++++++++++++++++ > qapi/migration.json | 16 ++++++++++++++++ > 2 files changed, 43 insertions(+) > > diff --git a/migration/migration.c b/migration/migration.c > index bb57ed9ade..139abec0c3 100644 > --- a/migration/migration.c > +++ b/migration/migration.c > @@ -1448,6 +1448,33 @@ void qmp_migrate_recover(const char *uri, Error **errp) > qemu_start_incoming_migration(uri, errp); > } > > +void qmp_migrate_pause(Error **errp) > +{ > + MigrationState *ms = migrate_get_current(); > + MigrationIncomingState *mis = migration_incoming_get_current(); > + int ret; > + > + if (ms->state == MIGRATION_STATUS_POSTCOPY_ACTIVE) { > + /* Source side, during postcopy */ > + ret = qemu_file_shutdown(ms->to_dst_file); This doesn't feel thread safe; although I'm not sure how to make it so. If the migration finishes just after we check the state but before the shutdown we end up using a bogus QEMUFile* Making all the places that close a QEMUFile* set hte pointer Null before they do the close doesn't help because you still race with that. (The race is small, but still) Dave > + if (ret) { > + error_setg(errp, "Failed to pause source migration"); > + } > + return; > + } > + > + if (mis->state == MIGRATION_STATUS_POSTCOPY_ACTIVE) { > + ret = qemu_file_shutdown(mis->from_src_file); > + if (ret) { > + error_setg(errp, "Failed to pause destination migration"); > + } > + return; > + } > + > + error_setg(errp, "migrate-pause is currently only supported " > + "during postcopy-active state"); > +} > + > bool migration_is_blocked(Error **errp) > { > if (qemu_savevm_state_blocked(errp)) { > diff --git a/qapi/migration.json b/qapi/migration.json > index dfbcb02d4c..3d9cfeb8f1 100644 > --- a/qapi/migration.json > +++ b/qapi/migration.json > @@ -1192,3 +1192,19 @@ > ## > { 'command': 'migrate-recover', 'data': { 'uri': 'str' }, > 'allow-oob': true } > + > +## > +# @migrate-pause: > +# > +# Pause a migration. Currently it only supports postcopy. > +# > +# Returns: nothing. > +# > +# Example: > +# > +# -> { "execute": "migrate-pause" } > +# <- { "return": {} } > +# > +# Since: 2.12 > +## > +{ 'command': 'migrate-pause', 'allow-oob': true } > -- > 2.14.3 > -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK