From patchwork Fri Sep 17 05:40:42 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: John Snow X-Patchwork-Id: 12501077 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=-13.5 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 3E48EC433EF for ; Fri, 17 Sep 2021 05:50:49 +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 74B5661130 for ; Fri, 17 Sep 2021 05:50:48 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 74B5661130 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=nongnu.org Received: from localhost ([::1]:53056 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1mR6lr-0002yP-Gq for qemu-devel@archiver.kernel.org; Fri, 17 Sep 2021 01:50:47 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:48302) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mR6cr-00058M-NP for qemu-devel@nongnu.org; Fri, 17 Sep 2021 01:41:29 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:35034) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mR6ci-0003Yf-FV for qemu-devel@nongnu.org; Fri, 17 Sep 2021 01:41:25 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1631857279; 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=zH5F3uen7nd7ziiWf9KhG96id2plwtBUemPAKgK2NTg=; b=eLt/8p/k6bUa87AeiO9lXEOpoPywkdRnWL4lVjOUgA4GX/vsV1N8Rcy+Ymb+EPoplbRITv LQCIKza5OATJSnYTOwuLpmbavFelKAMAb+QIzk6BmwIDNlCzVyfFuUvkNOdunxqmiQXjC4 LdpEwrWLCA3H8tYs+U+iRzQy1TNMASA= 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-582-0UeBdukINGCIweDYjEFo0Q-1; Fri, 17 Sep 2021 01:41:18 -0400 X-MC-Unique: 0UeBdukINGCIweDYjEFo0Q-1 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 90E18802936; Fri, 17 Sep 2021 05:41:17 +0000 (UTC) Received: from scv.redhat.com (unknown [10.22.11.132]) by smtp.corp.redhat.com (Postfix) with ESMTP id 2369B7A8CE; Fri, 17 Sep 2021 05:41:16 +0000 (UTC) From: John Snow To: qemu-devel@nongnu.org Subject: [PATCH 10/15] python/machine: Add support for AQMP backend Date: Fri, 17 Sep 2021 01:40:42 -0400 Message-Id: <20210917054047.2042843-11-jsnow@redhat.com> In-Reply-To: <20210917054047.2042843-1-jsnow@redhat.com> References: <20210917054047.2042843-1-jsnow@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=jsnow@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Received-SPF: pass client-ip=170.10.133.124; envelope-from=jsnow@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -31 X-Spam_score: -3.2 X-Spam_bar: --- X-Spam_report: (-3.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.392, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action 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: Kevin Wolf , Vladimir Sementsov-Ogievskiy , Eduardo Habkost , qemu-block@nongnu.org, Hanna Reitz , Cleber Rosa , John Snow Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" To use the AQMP backend, Machine just needs to be a little more diligent about what happens when closing a QMP connection. The operation is no longer a freebie in the async world. Because async QMP continues to check for messages asynchronously, it's almost certainly likely that the loop will have exited due to EOF after issuing the last 'quit' command. That error will ultimately be bubbled up when attempting to close the QMP connection. The manager class here then is free to discard it if it was expected. Signed-off-by: John Snow --- Yes, I regret that this class has become quite a dumping ground for complexity around the exit path. It's in need of a refactor to help separate out the exception handling and cleanup mechanisms from the VM-related stuff, but it's not a priority to do that just yet -- but it's on the list. --- python/qemu/machine/machine.py | 51 ++++++++++++++++++++++++++++++---- 1 file changed, 46 insertions(+), 5 deletions(-) diff --git a/python/qemu/machine/machine.py b/python/qemu/machine/machine.py index 6e58d2f951..8f5a6649e5 100644 --- a/python/qemu/machine/machine.py +++ b/python/qemu/machine/machine.py @@ -342,9 +342,15 @@ def _post_shutdown(self) -> None: # Comprehensive reset for the failed launch case: self._early_cleanup() - if self._qmp_connection: - self._qmp.close() - self._qmp_connection = None + try: + self._close_qmp_connection() + except Exception as err: # pylint: disable=broad-except + LOG.warning( + "Exception closing QMP connection: %s", + str(err) if str(err) else type(err).__name__ + ) + finally: + assert self._qmp_connection is None self._close_qemu_log_file() @@ -420,6 +426,31 @@ def _launch(self) -> None: close_fds=False) self._post_launch() + def _close_qmp_connection(self) -> None: + """ + Close the underlying QMP connection, if any. + + Dutifully report errors that occurred while closing, but assume + that any error encountered indicates an abnormal termination + process and not a failure to close. + """ + if self._qmp_connection is None: + return + + try: + self._qmp.close() + except EOFError: + # EOF can occur as an Exception here when using the Async + # QMP backend. It indicates that the server closed the + # stream. If we successfully issued 'quit' at any point, + # then this was expected. If the remote went away without + # our permission, it's worth reporting that as an abnormal + # shutdown case. + if not self._has_quit: + raise + finally: + self._qmp_connection = None + def _early_cleanup(self) -> None: """ Perform any cleanup that needs to happen before the VM exits. @@ -461,8 +492,18 @@ def _soft_shutdown(self, timeout: Optional[int]) -> None: if self._qmp_connection: if not self._has_quit: - # Might raise ConnectionReset - self.qmp('quit') + try: + # May raise ExecInterruptedError or StateError if the + # connection dies or has already died. + self.qmp('quit') + finally: + # If 'quit' fails, we'll still want to call close(), + # which will raise any final errors that may have + # occurred while trying to send 'quit'. + self._close_qmp_connection() + else: + # Regardless, we want to tidy up the socket. + self._close_qmp_connection() # May raise subprocess.TimeoutExpired self._subp.wait(timeout=timeout)