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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4DACAC433F5 for ; Thu, 18 Nov 2021 20:48:42 +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 F08F86128C for ; Thu, 18 Nov 2021 20:48:41 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org F08F86128C 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]:47114 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1mnoKm-0004XT-PK for qemu-devel@archiver.kernel.org; Thu, 18 Nov 2021 15:48:40 -0500 Received: from eggs.gnu.org ([209.51.188.92]:58748) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mnoIh-0001ov-SD for qemu-devel@nongnu.org; Thu, 18 Nov 2021 15:46:31 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:33775) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mnoIg-0000O7-BW for qemu-devel@nongnu.org; Thu, 18 Nov 2021 15:46:31 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1637268389; 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=f3j2XgNV29TROon2KsCm5KyGGCp4QNigpFpnQvIxyw0=; b=bqYRdsKC9a9m2O/6Gh4zLw5Z3TQckYDEkai0Cr65svZjqoXFULkzfW8joAQ+jnEz+xfyCb 47ELUWkL+JGMqhMe60Ni6TJizgC8u3yHd55SSes3FeLks2eGWp/4AXoljz613/ETZ48ueq vLl6W8yxu0C8JFq129WB+lwKWiGTp6s= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-22-KResAx11OPyKgQvLRwgmig-1; Thu, 18 Nov 2021 15:46:28 -0500 X-MC-Unique: KResAx11OPyKgQvLRwgmig-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 8FA2987D541 for ; Thu, 18 Nov 2021 20:46:26 +0000 (UTC) Received: from scv.redhat.com (unknown [10.22.18.244]) by smtp.corp.redhat.com (Postfix) with ESMTP id DBAA867842; Thu, 18 Nov 2021 20:46:25 +0000 (UTC) From: John Snow To: qemu-devel@nongnu.org Subject: [PATCH 5/7] python/machine: handle "fast" QEMU terminations Date: Thu, 18 Nov 2021 15:46:18 -0500 Message-Id: <20211118204620.1897674-6-jsnow@redhat.com> In-Reply-To: <20211118204620.1897674-1-jsnow@redhat.com> References: <20211118204620.1897674-1-jsnow@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 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 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset="US-ASCII" 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: -34 X-Spam_score: -3.5 X-Spam_bar: --- X-Spam_report: (-3.5 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.698, 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: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Thomas Huth , John Snow , Eduardo Habkost , Cleber Rosa Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" In the case that the QEMU process actually launches -- but then dies so quickly that we can't establish a QMP connection to it -- QEMUMachine currently calls _post_shutdown() assuming that it never launched the VM process. This isn't true, though: it "merely" may have failed to establish a QMP connection and the process is in the middle of its own exit path. If we don't wait for the subprocess, the caller may get a bogus `None` return for .exitcode(). This behavior was observed from device-crash-test; after the switch to Async QMP, the timings were changed such that it was now seemingly possible to witness the failure of "vm.launch()" *prior* to the exitcode becoming available. The semantic of the `_launched` property is changed in this patch. Instead of representing the condition "launch() executed successfully", it will now represent "has forked a child process successfully". This way, wait() when called in the exit path won't become a no-op. Signed-off-by: John Snow Signed-off-by: John Snow --- python/qemu/machine/machine.py | 19 ++++++++++++------- 1 file changed, 12 insertions(+), 7 deletions(-) diff --git a/python/qemu/machine/machine.py b/python/qemu/machine/machine.py index f92e73de40..67ab06ca2b 100644 --- a/python/qemu/machine/machine.py +++ b/python/qemu/machine/machine.py @@ -349,9 +349,6 @@ def _post_shutdown(self) -> None: Called to cleanup the VM instance after the process has exited. May also be called after a failed launch. """ - # Comprehensive reset for the failed launch case: - self._early_cleanup() - try: self._close_qmp_connection() except Exception as err: # pylint: disable=broad-except @@ -400,9 +397,16 @@ def launch(self) -> None: try: self._launch() - self._launched = True except: - self._post_shutdown() + # We may have launched the process but it may + # have exited before we could connect via QMP. + # Assume the VM didn't launch or is exiting. + # If we don't wait for the process, exitcode() may still be + # 'None' by the time control is ceded back to the caller. + if self._launched: + self.wait() + else: + self._post_shutdown() LOG.debug('Error launching VM') if self._qemu_full_args: @@ -426,6 +430,7 @@ def _launch(self) -> None: stderr=subprocess.STDOUT, shell=False, close_fds=False) + self._launched = True self._post_launch() def _close_qmp_connection(self) -> None: @@ -457,8 +462,8 @@ def _early_cleanup(self) -> None: """ Perform any cleanup that needs to happen before the VM exits. - May be invoked by both soft and hard shutdown in failover scenarios. - Called additionally by _post_shutdown for comprehensive cleanup. + This method may be called twice upon shutdown, once each by soft + and hard shutdown in failover scenarios. """ # If we keep the console socket open, we may deadlock waiting # for QEMU to exit, while QEMU is waiting for the socket to -- 2.31.1