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=-17.2 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,URIBL_BLOCKED, 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 525DAC433E0 for ; Wed, 27 Jan 2021 08:16:48 +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 DA45B20754 for ; Wed, 27 Jan 2021 08:16:47 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org DA45B20754 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.75798.136571 (Exim 4.92) (envelope-from ) id 1l4g0F-0005l2-PH; Wed, 27 Jan 2021 08:16:39 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 75798.136571; Wed, 27 Jan 2021 08:16:39 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1l4g0F-0005kv-MG; Wed, 27 Jan 2021 08:16:39 +0000 Received: by outflank-mailman (input) for mailman id 75798; Wed, 27 Jan 2021 08:16:38 +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 1l4g0E-0005ki-CH for xen-devel@lists.xenproject.org; Wed, 27 Jan 2021 08:16:38 +0000 Received: from mx2.suse.de (unknown [195.135.220.15]) by us1-amaz-eas2.inumbo.com (Halon) with ESMTPS id 088ee26f-2438-44ac-b47c-6ddbbf0d9055; Wed, 27 Jan 2021 08:16:37 +0000 (UTC) Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id E0570AF17; Wed, 27 Jan 2021 08:16:36 +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: 088ee26f-2438-44ac-b47c-6ddbbf0d9055 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=1611735397; 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=QpyRMXe7gyQJEoJJGBUBHj/cowjnW/uFCjUcSR4dZrw=; b=YOPgBPWtycIF312nHNy3XHFwMyg5jDj4ig9C8PLwYuHLp7mWC4dyfQ6lelf3SltfPsbKz6 ho68v5JZPtfjgkErNLzXxKH3492P/knZKVY6k59rWW25usasKvDBALtofRi2OHucv34R5s NqX5WXa4BuTsR/kb+lZwpyTXdW3Qbic= Subject: [PATCH v5 3/6] 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: <306e62e8-9070-2db9-c959-858465c50c1d@suse.com> Message-ID: Date: Wed, 27 Jan 2021 09:16:36 +0100 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.6.1 MIME-Version: 1.0 In-Reply-To: <306e62e8-9070-2db9-c959-858465c50c1d@suse.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit 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 @@ -610,17 +610,14 @@ 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 ) { @@ -1044,16 +1041,13 @@ 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)) ) {