From patchwork Tue Jan 5 13:11:39 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jan Beulich X-Patchwork-Id: 11998863 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=-17.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,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 9261BC433E0 for ; Tue, 5 Jan 2021 13:12:01 +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 4F43122AAB for ; Tue, 5 Jan 2021 13:12:01 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4F43122AAB 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.61938.109277 (Exim 4.92) (envelope-from ) id 1kwm7j-0000lH-AG; Tue, 05 Jan 2021 13:11:43 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 61938.109277; Tue, 05 Jan 2021 13:11:43 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1kwm7j-0000lA-7I; Tue, 05 Jan 2021 13:11:43 +0000 Received: by outflank-mailman (input) for mailman id 61938; Tue, 05 Jan 2021 13:11:42 +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 1kwm7h-0000l1-Th for xen-devel@lists.xenproject.org; Tue, 05 Jan 2021 13:11:41 +0000 Received: from mx2.suse.de (unknown [195.135.220.15]) by us1-amaz-eas2.inumbo.com (Halon) with ESMTPS id 7ce02c72-6601-4dca-b9ec-dd518f66e3cc; Tue, 05 Jan 2021 13:11:41 +0000 (UTC) Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 48480AD0B; Tue, 5 Jan 2021 13:11:40 +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: 7ce02c72-6601-4dca-b9ec-dd518f66e3cc 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=1609852300; 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=jpDPxfUXwQJobIQUxX1fnLD15/1oKgv3k1efx+tAnAE=; b=GekgU3LU5vpUV6FglutXN4q5kx/j3iIBoLIiRKy0WPCU/DN/M00r38NLNQFCarKGUuLOAY c3qpjgIPdtIxIYeeLB0SNIBkiP9XMVjX57ayphoT83ZHWqfSCtY8xt+IShoDE6t8LDNu4c wXVyJE+iJ2cVaVeR+Kahb1ng3O+S3nM= Subject: [PATCH v4 06/10] evtchn: slightly defer lock acquire where possible From: Jan Beulich To: "xen-devel@lists.xenproject.org" Cc: Andrew Cooper , George Dunlap , Ian Jackson , Julien Grall , Wei Liu , Stefano Stabellini References: Message-ID: <50d76d71-7e76-8c4d-0546-bf690085036b@suse.com> Date: Tue, 5 Jan 2021 14:11:39 +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: Content-Language: en-US port_is_valid() and evtchn_from_port() are fine to use without holding any locks. Accordingly acquire the per-domain lock slightly later in evtchn_close() and evtchn_bind_vcpu(). Signed-off-by: Jan Beulich --- v4: New. --- a/xen/common/event_channel.c +++ b/xen/common/event_channel.c @@ -604,17 +604,14 @@ int evtchn_close(struct domain *d1, int int port2; long rc = 0; - again: - write_lock(&d1->event_lock); - if ( !port_is_valid(d1, port1) ) - { - rc = -EINVAL; - goto out; - } + return -EINVAL; chn1 = evtchn_from_port(d1, port1); + again: + write_lock(&d1->event_lock); + /* Guest cannot close a Xen-attached event channel. */ if ( unlikely(consumer_is_xen(chn1)) && guest ) { @@ -1039,16 +1036,13 @@ long evtchn_bind_vcpu(unsigned int port, if ( (v = domain_vcpu(d, vcpu_id)) == NULL ) return -ENOENT; - write_lock(&d->event_lock); - if ( !port_is_valid(d, port) ) - { - rc = -EINVAL; - goto out; - } + return -EINVAL; chn = evtchn_from_port(d, port); + write_lock(&d->event_lock); + /* Guest cannot re-bind a Xen-attached event channel. */ if ( unlikely(consumer_is_xen(chn)) ) {