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 F315AC7618D for ; Thu, 6 Apr 2023 10:08:48 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1pkMXL-0005vo-Ev; Thu, 06 Apr 2023 06:08:11 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1pkMXH-0005vS-In for qemu-devel@nongnu.org; Thu, 06 Apr 2023 06:08:07 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1pkMXF-0006Ln-5v for qemu-devel@nongnu.org; Thu, 06 Apr 2023 06:08:07 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1680775684; 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; bh=Xitcq6J1Wfwuna3Y2hnE6Uowk/aE/Q5WE7yuJGp2k4U=; b=fOJ+FqOqfpMv6vZMqcefVKJKK7AE4jxBRexV1ugBKHH965/6uYQQeZBODkZl8Xu3kpqe6E X4Wgs9kzUAvm5UqlYB8AZbOky/lmwsVm2DZKxaxPFzX2W6nV++C4HxgIuYm69hrJvXnzkV JoviHhHHX/OySATJ+ylkvkI6Sto1vfc= Received: from mail-ed1-f69.google.com (mail-ed1-f69.google.com [209.85.208.69]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-412-fEg8qQm8Mlm2okVQdhAfcA-1; Thu, 06 Apr 2023 06:08:02 -0400 X-MC-Unique: fEg8qQm8Mlm2okVQdhAfcA-1 Received: by mail-ed1-f69.google.com with SMTP id c11-20020a509f8b000000b00501e2facf47so52695623edf.16 for ; Thu, 06 Apr 2023 03:08:02 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1680775681; x=1683367681; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=Xitcq6J1Wfwuna3Y2hnE6Uowk/aE/Q5WE7yuJGp2k4U=; b=APSuJJlDrNao0WdOorCykBGcBPiSOcWyhwbYFXu0Rq4FsuoLrroO6IQv/vQJvXvZX7 9QiYPdyhjC3zEVtRXdLXsGOIUXOYT3xZ4V6IBzWHiMHG2jQrp7vxF91Y4MwmWwg0nAdO 9i5OmIdPzbNdlxZrLpM39GEWean/Cfno2pWkD6Nw890P5KJ/Dg3jl2jLPHI3Ki4ibyne ZPzo8ax4xz9MhSKsxxF2JXm9y24aYkt3DHuEkFTN1+Jpm6gfhIgQ4xAL/EcpQSr+/UUl 6+4P5HPGe3Ycxyttwj3qdecypfYuOANYlAth5hAfTcRGk/ys5ONLVtUzpa36JfWsFK3f Otsg== X-Gm-Message-State: AAQBX9fWVg278HVrf5YB8Z3tHXhAx7P/HzuvaK5grHlmFMrI9z+Z/FCZ 3selxPnDKRDAOpS0iaPcfkHnpDc+cDapM90WVLTeYNQjOXuayiphBJuM0lDdAZ0VB3LXF3ozOhz itKhQAcp4J/c+PEHIcEReD10KjhUSkvJmEeKe03QNnVmVOy6439MQ7xWWO0KBiukHag2zjeKKs5 E= X-Received: by 2002:a17:906:2cd5:b0:8b8:c06e:52d8 with SMTP id r21-20020a1709062cd500b008b8c06e52d8mr5509814ejr.36.1680775681267; Thu, 06 Apr 2023 03:08:01 -0700 (PDT) X-Google-Smtp-Source: AKy350b8WzpYVxzSnmtW4c7y9h+9l7FzMPxL8WZLKibJ/e1KCnagEVLDLY3cIsa/1nNDFo2tDrLvgA== X-Received: by 2002:a17:906:2cd5:b0:8b8:c06e:52d8 with SMTP id r21-20020a1709062cd500b008b8c06e52d8mr5509796ejr.36.1680775680893; Thu, 06 Apr 2023 03:08:00 -0700 (PDT) Received: from [192.168.10.118] ([2001:b07:6468:f312:1c09:f536:3de6:228c]) by smtp.gmail.com with ESMTPSA id y7-20020a17090668c700b009327ed171f2sm599494ejr.129.2023.04.06.03.07.59 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 06 Apr 2023 03:08:00 -0700 (PDT) From: Paolo Bonzini To: qemu-devel@nongnu.org Cc: stefanha@redhat.com Subject: [PATCH for-8.1] qemu-coroutine: remove qatomic_mb_read() Date: Thu, 6 Apr 2023 12:07:58 +0200 Message-Id: <20230406100759.240870-1-pbonzini@redhat.com> X-Mailer: git-send-email 2.39.2 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=170.10.133.124; envelope-from=pbonzini@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, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 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-bounces+qemu-devel=archiver.kernel.org@nongnu.org Replace with an explicit barrier and a comment. Signed-off-by: Paolo Bonzini --- util/qemu-coroutine.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/util/qemu-coroutine.c b/util/qemu-coroutine.c index 849452369201..17a88f65053e 100644 --- a/util/qemu-coroutine.c +++ b/util/qemu-coroutine.c @@ -127,9 +127,13 @@ void qemu_aio_coroutine_enter(AioContext *ctx, Coroutine *co) Coroutine *to = QSIMPLEQ_FIRST(&pending); CoroutineAction ret; - /* Cannot rely on the read barrier for to in aio_co_wake(), as there are - * callers outside of aio_co_wake() */ - const char *scheduled = qatomic_mb_read(&to->scheduled); + /* + * Read to before to->scheduled; pairs with qatomic_cmpxchg in + * qemu_co_sleep(), aio_co_schedule() etc. + */ + smp_read_barrier_depends(); + + const char *scheduled = qatomic_read(&to->scheduled); QSIMPLEQ_REMOVE_HEAD(&pending, co_queue_next); -- 2.39.2