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 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 273C5C433F5 for ; Tue, 26 Apr 2022 08:54:42 +0000 (UTC) Received: from localhost ([::1]:60126 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1njGy1-0001nz-7f for qemu-devel@archiver.kernel.org; Tue, 26 Apr 2022 04:54:41 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:43332) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1njGux-0006uY-Ja for qemu-devel@nongnu.org; Tue, 26 Apr 2022 04:51:34 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]:47682) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1njGur-0000dN-SK for qemu-devel@nongnu.org; Tue, 26 Apr 2022 04:51:27 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1650963085; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=TAF+iXN/P5vG3kfcg8FnN98Snqyu8MB1Oeu77oXegUk=; b=fkZK145glStlEdyXxtiGDuAlMOHmaBSLkFWier0L6pFnNhMMHbz5dg+rXGv7x4oLl2ubE0 5+xYOlaxrww+t5ZG8uoCup97c6qwnfn5aErv21yz6k+Lq8a06QkdNfdNOy28uxWrIaYtNC PWv9MNK8N1zshlwyi4235aj0LZtP5RM= 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-205-wbAyKP0ZNyyN_Q2epr6AaQ-1; Tue, 26 Apr 2022 04:51:18 -0400 X-MC-Unique: wbAyKP0ZNyyN_Q2epr6AaQ-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.rdu2.redhat.com [10.11.54.2]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id F2391811E7A; Tue, 26 Apr 2022 08:51:17 +0000 (UTC) Received: from virtlab701.virt.lab.eng.bos.redhat.com (virtlab701.virt.lab.eng.bos.redhat.com [10.19.152.228]) by smtp.corp.redhat.com (Postfix) with ESMTP id ADF8340D282C; Tue, 26 Apr 2022 08:51:17 +0000 (UTC) From: Emanuele Giuseppe Esposito To: qemu-block@nongnu.org Subject: [RFC PATCH v2 1/8] aio_wait_kick: add missing memory barrier Date: Tue, 26 Apr 2022 04:51:07 -0400 Message-Id: <20220426085114.199647-2-eesposit@redhat.com> In-Reply-To: <20220426085114.199647-1-eesposit@redhat.com> References: <20220426085114.199647-1-eesposit@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 2.84 on 10.11.54.2 Received-SPF: pass client-ip=170.10.129.124; envelope-from=eesposit@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -28 X-Spam_score: -2.9 X-Spam_bar: -- X-Spam_report: (-2.9 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.082, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, 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: , Cc: Kevin Wolf , Fam Zheng , Vladimir Sementsov-Ogievskiy , Emanuele Giuseppe Esposito , qemu-devel@nongnu.org, Hanna Reitz , Stefan Hajnoczi , Paolo Bonzini , John Snow Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" It seems that aio_wait_kick always required a memory barrier or atomic operation in the caller, but almost nobody actually took care of doing it. Let's put the barrier in the function instead. Signed-off-by: Emanuele Giuseppe Esposito --- util/aio-wait.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/util/aio-wait.c b/util/aio-wait.c index bdb3d3af22..c0a343ac87 100644 --- a/util/aio-wait.c +++ b/util/aio-wait.c @@ -35,7 +35,8 @@ static void dummy_bh_cb(void *opaque) void aio_wait_kick(void) { - /* The barrier (or an atomic op) is in the caller. */ + smp_mb(); + if (qatomic_read(&global_aio_wait.num_waiters)) { aio_bh_schedule_oneshot(qemu_get_aio_context(), dummy_bh_cb, NULL); } -- 2.31.1