From patchwork Fri Sep 2 06:41:27 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Jason Wang X-Patchwork-Id: 12963687 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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id 109C3C6FA81 for ; Fri, 2 Sep 2022 06:54:55 +0000 (UTC) Received: from localhost ([::1]:45768 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1oU0Zq-0007q2-UO for qemu-devel@archiver.kernel.org; Fri, 02 Sep 2022 02:54:54 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:59952) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1oU0Ne-0007RH-89 for qemu-devel@nongnu.org; Fri, 02 Sep 2022 02:42:18 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:39152) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1oU0Nc-0004rl-NH for qemu-devel@nongnu.org; Fri, 02 Sep 2022 02:42:17 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1662100936; 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=Ez+pjZ5RN+UQVMXyW1wujNjESHc87Iu5UQTLDPMiMT0=; b=fCTBW7k1YiBbp/Jl0IXluU4+hBnACLY4ghqC4rWvAVFc6TAAzxKkmFZBI/3WEdaZWgH2r7 PuMrhpkqjTcNxInnkIKTiihMjtrWOJXnfL1Ksou9boJfkRaoBJjrsaT09vp77hjnqMQwzf nlJF1danCQBgcPzkQ88jShVDTOJwgbY= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-112-Pqc0F6uIPRWTgb2olU5HZw-1; Fri, 02 Sep 2022 02:42:15 -0400 X-MC-Unique: Pqc0F6uIPRWTgb2olU5HZw-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.rdu2.redhat.com [10.11.54.7]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id B675B80C8F0; Fri, 2 Sep 2022 06:42:14 +0000 (UTC) Received: from localhost.localdomain (ovpn-12-152.pek2.redhat.com [10.72.12.152]) by smtp.corp.redhat.com (Postfix) with ESMTP id 9BBAA1410F3C; Fri, 2 Sep 2022 06:42:12 +0000 (UTC) From: Jason Wang To: qemu-devel@nongnu.org, peter.maydell@linaro.org Cc: =?utf-8?q?Eugenio_P=C3=A9rez?= , Jason Wang Subject: [PULL 10/21] vhost: Delete useless read memory barrier Date: Fri, 2 Sep 2022 14:41:27 +0800 Message-Id: <20220902064138.56468-11-jasowang@redhat.com> In-Reply-To: <20220902064138.56468-1-jasowang@redhat.com> References: <20220902064138.56468-1-jasowang@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.85 on 10.11.54.7 Received-SPF: pass client-ip=170.10.133.124; envelope-from=jasowang@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 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: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" From: Eugenio Pérez As discussed in previous series [1], this memory barrier is useless with the atomic read of used idx at vhost_svq_more_used. Deleting it. [1] https://lists.nongnu.org/archive/html/qemu-devel/2022-07/msg02616.html Signed-off-by: Eugenio Pérez Acked-by: Jason Wang Signed-off-by: Jason Wang --- hw/virtio/vhost-shadow-virtqueue.c | 3 --- 1 file changed, 3 deletions(-) diff --git a/hw/virtio/vhost-shadow-virtqueue.c b/hw/virtio/vhost-shadow-virtqueue.c index b35aeef..8df5296 100644 --- a/hw/virtio/vhost-shadow-virtqueue.c +++ b/hw/virtio/vhost-shadow-virtqueue.c @@ -509,9 +509,6 @@ size_t vhost_svq_poll(VhostShadowVirtqueue *svq) if (unlikely(g_get_monotonic_time() - start_us > 10e6)) { return 0; } - - /* Make sure we read new used_idx */ - smp_rmb(); } while (true); }