From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:42455) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fa1aq-0004R1-VV for qemu-devel@nongnu.org; Mon, 02 Jul 2018 12:22:27 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fa1ap-0006c0-J5 for qemu-devel@nongnu.org; Mon, 02 Jul 2018 12:22:24 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:54930 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 1fa1ap-0006bk-Dm for qemu-devel@nongnu.org; Mon, 02 Jul 2018 12:22:23 -0400 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.rdu2.redhat.com [10.11.54.5]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 14E3540250FF for ; Mon, 2 Jul 2018 16:22:23 +0000 (UTC) From: Markus Armbruster Date: Mon, 2 Jul 2018 18:21:50 +0200 Message-Id: <20180702162218.13678-5-armbru@redhat.com> In-Reply-To: <20180702162218.13678-1-armbru@redhat.com> References: <20180702162218.13678-1-armbru@redhat.com> Subject: [Qemu-devel] [PATCH 04/32] qmp: Document COMMAND_DROPPED design flaw List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: peterx@redhat.com, eblake@redhat.com, stefanha@redhat.com, dgilbert@redhat.com Events are broadcast to all monitors. If another monitor's client has a command with the same ID in flight, the event will incorrectly claim that command was dropped. This must be fixed before out-of-band execution can graduate from "experimental". Signed-off-by: Markus Armbruster --- monitor.c | 6 ++++++ qapi/misc.json | 3 +++ 2 files changed, 9 insertions(+) diff --git a/monitor.c b/monitor.c index 3fb05d50aa..96e87d8664 100644 --- a/monitor.c +++ b/monitor.c @@ -4330,6 +4330,12 @@ static void handle_qmp_command(JSONMessageParser *parser, GQueue *tokens) /* Drop the request if queue is full. */ if (mon->qmp.qmp_requests->length >= QMP_REQ_QUEUE_LEN_MAX) { qemu_mutex_unlock(&mon->qmp.qmp_queue_lock); + /* + * FIXME @id's scope is just @mon, and broadcasting it is + * wrong. If another monitor's client has a command with + * the same ID in flight, the event will incorrectly claim + * that command was dropped. + */ qapi_event_send_command_dropped(id, COMMAND_DROP_REASON_QUEUE_FULL, &error_abort); diff --git a/qapi/misc.json b/qapi/misc.json index 0446c3e48e..74cd97f237 100644 --- a/qapi/misc.json +++ b/qapi/misc.json @@ -3454,6 +3454,9 @@ # only be dropped when the oob capability is enabled. # # @id: The dropped command's "id" field. +# FIXME Broken by design. Events are broadcast to all monitors. If +# another monitor's client has a command with the same ID in flight, +# the event will incorrectly claim that command was dropped. # # @reason: The reason why the command is dropped. # -- 2.17.1