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=-14.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,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 43238C433E0 for ; Tue, 22 Dec 2020 07:50:31 +0000 (UTC) Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (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 EFB30225AB for ; Tue, 22 Dec 2020 07:50:30 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org EFB30225AB Authentication-Results: mail.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=xen-devel-bounces@lists.xenproject.org Received: from list by lists.xenproject.org with outflank-mailman.57660.100963 (Exim 4.92) (envelope-from ) id 1krcQt-0003gF-UV; Tue, 22 Dec 2020 07:50:11 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 57660.100963; Tue, 22 Dec 2020 07:50:11 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1krcQt-0003g8-Pz; Tue, 22 Dec 2020 07:50:11 +0000 Received: by outflank-mailman (input) for mailman id 57660; Tue, 22 Dec 2020 07:50:10 +0000 Received: from all-amaz-eas1.inumbo.com ([34.197.232.57] helo=us1-amaz-eas2.inumbo.com) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1krcQs-0003g2-5K for xen-devel@lists.xenproject.org; Tue, 22 Dec 2020 07:50:10 +0000 Received: from mx2.suse.de (unknown [195.135.220.15]) by us1-amaz-eas2.inumbo.com (Halon) with ESMTPS id 12e7aba3-4278-413e-b663-91b8956623e3; Tue, 22 Dec 2020 07:50:09 +0000 (UTC) Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 5D7CBAD5C; Tue, 22 Dec 2020 07:50:08 +0000 (UTC) X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" X-Inumbo-ID: 12e7aba3-4278-413e-b663-91b8956623e3 X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1608623408; h=from:from:reply-to: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=sEhkxx0qP1O3PJjv/Pls4ZqvC+Kqeb/UeF5x87ct/ZI=; b=keqtgod9xw/Lqu3/6i6y2tnOnlmISnl/R4UBADypf9EAYfqC2c/G9f+bVrFHArQjP/XQZm PohWHO26Sq34DJWPgrdcInOKMG9r8nLaPJnPiGReelzaadWFt8uEyIBieVhY9YfIa04CPA vNxkEBpcfCJd5XoKvKd8F8nix5Gom1s= Subject: Re: [PATCH 2/3] xen/domain: Introduce domain_teardown() To: Andrew Cooper , Julien Grall Cc: =?UTF-8?Q?Roger_Pau_Monn=c3=a9?= , Wei Liu , Stefano Stabellini , Volodymyr Babchuk , Xen-devel References: <20201221181446.7791-1-andrew.cooper3@citrix.com> <20201221181446.7791-3-andrew.cooper3@citrix.com> <7edf2139-b63e-00c9-7172-524566f942ae@citrix.com> From: Jan Beulich Message-ID: <09fd7598-9899-9b4c-68ba-f90b3bc47d6f@suse.com> Date: Tue, 22 Dec 2020 08:50:07 +0100 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.6.0 MIME-Version: 1.0 In-Reply-To: <7edf2139-b63e-00c9-7172-524566f942ae@citrix.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit On 21.12.2020 19:45, Andrew Cooper wrote: > On 21/12/2020 18:36, Julien Grall wrote: >>> @@ -553,6 +606,9 @@ struct domain *domain_create(domid_t domid, >>>       if ( init_status & INIT_watchdog ) >>>           watchdog_domain_destroy(d); >>>   +    /* Must not hit a continuation in this context. */ >>> +    ASSERT(domain_teardown(d) == 0); >> The ASSERT() will become a NOP in production build, so >> domain_teardown_down() will not be called. > > Urgh - its not really a nop, but it's evaluation isn't symmetric between > debug and release builds.  I'll need an extra local variable. Or use ASSERT_UNREACHABLE(). (I admit I don't really like the resulting constructs, and would like to propose an alternative, even if I fear it'll be controversial.) >> However, I think it would be better if we pass an extra argument to >> indicated wheter the code is allowed to preempt. This would make the >> preemption check more obvious in evtchn_destroy() compare to the >> current d->is_dying != DOMDYING_dead. > > We can have a predicate if you'd prefer, but plumbing an extra parameter > is wasteful, and can only cause confusion if it is out of sync with > d->is_dying. I agree here - it wasn't so long ago that event_channel.c gained a DOMDYING_dead check, and I don't see why we shouldn't extend this approach to here and elsewhere. Jan