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 7EBBBC4707F for ; Thu, 27 May 2021 11:28:21 +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 3D0DA613AF for ; Thu, 27 May 2021 11:28:21 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3D0DA613AF 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.133020.248036 (Exim 4.92) (envelope-from ) id 1lmEBS-0000DU-KV; Thu, 27 May 2021 11:28:14 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 133020.248036; Thu, 27 May 2021 11:28:14 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1lmEBS-0000DN-HZ; Thu, 27 May 2021 11:28:14 +0000 Received: by outflank-mailman (input) for mailman id 133020; Thu, 27 May 2021 11:28:13 +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 1lmEBR-0000DD-6l for xen-devel@lists.xenproject.org; Thu, 27 May 2021 11:28:13 +0000 Received: from smtp-out1.suse.de (unknown [195.135.220.28]) by us1-amaz-eas2.inumbo.com (Halon) with ESMTPS id b9f8fd59-2afa-49d5-b336-e0008c844830; Thu, 27 May 2021 11:28:12 +0000 (UTC) Received: from imap.suse.de (imap-alt.suse-dmz.suse.de [192.168.254.47]) (using TLSv1.2 with cipher ECDHE-ECDSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp-out1.suse.de (Postfix) with ESMTPS id 9829D218DD; Thu, 27 May 2021 11:28:11 +0000 (UTC) Received: from director2.suse.de (director2.suse-dmz.suse.de [192.168.254.72]) by imap.suse.de (Postfix) with ESMTPSA id 6653611A98; Thu, 27 May 2021 11:28:11 +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: b9f8fd59-2afa-49d5-b336-e0008c844830 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1622114891; 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=b6aTSYEJ4zMIzcsHnssUxQ3Bp2aABIpTEIa3bDkYDGg=; b=acmKoGYDeHF6DyeYESAaaMb1IsZc3GKsB6z74gGCyYraRgBjoalxJAAq/olGOXV3UARR7v mBckfAt+971c2kTSy84zXDvvaKDqZQRTdWh53ADL6NedLlQ5QeU+yUzG9WWfbP0d8OcZ1h iVArkE/bcz5klrhJAx9n5n8vN5ap8a8= Subject: [PATCH v6 1/3] 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 , =?UTF-8?Q?Roger_Pau_Monn=c3=a9?= References: <01bbf3d4-ca6a-e837-91fe-b34aa014564c@suse.com> Message-ID: <5939858e-1c7c-5658-bc2d-0c9024c74040@suse.com> Date: Thu, 27 May 2021 13:28:07 +0200 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.10.2 MIME-Version: 1.0 In-Reply-To: <01bbf3d4-ca6a-e837-91fe-b34aa014564c@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 --- v6: Re-base for re-ordering / shrinking of series. v4: New. --- a/xen/common/event_channel.c +++ b/xen/common/event_channel.c @@ -606,17 +606,14 @@ int evtchn_close(struct domain *d1, int int port2; long rc = 0; - again: - spin_lock(&d1->event_lock); - if ( !port_is_valid(d1, port1) ) - { - rc = -EINVAL; - goto out; - } + return -EINVAL; chn1 = evtchn_from_port(d1, port1); + again: + spin_lock(&d1->event_lock); + /* Guest cannot close a Xen-attached event channel. */ if ( unlikely(consumer_is_xen(chn1)) && guest ) { @@ -1041,16 +1038,13 @@ long evtchn_bind_vcpu(unsigned int port, if ( (v = domain_vcpu(d, vcpu_id)) == NULL ) return -ENOENT; - spin_lock(&d->event_lock); - if ( !port_is_valid(d, port) ) - { - rc = -EINVAL; - goto out; - } + return -EINVAL; chn = evtchn_from_port(d, port); + spin_lock(&d->event_lock); + /* Guest cannot re-bind a Xen-attached event channel. */ if ( unlikely(consumer_is_xen(chn)) ) {