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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 89B28C433F5 for ; Thu, 2 Dec 2021 11:26:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1357017AbhLBL3p (ORCPT ); Thu, 2 Dec 2021 06:29:45 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]:57682 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1345845AbhLBL3o (ORCPT ); Thu, 2 Dec 2021 06:29:44 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1638444382; 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=lDz7Gl7O/a6QxEzSyH8lRwP13RtbZV0kax667QfBu/c=; b=EF9rm+keEA60ywDxV1dna3wR2KkANUzHGCsw65kDpGAoU6QDqFBXtu+MsjI7HcYu3G4XYg XZ1mgKSGuS1GWeGHBNFhN4LGNpGSOZI35q1P4dsnET4TmUKQ8xplT1Z4QqkildXyMaGYJ+ 3aG+dm/ZOfGKWrRFzXHvVhW4vje6L7I= Received: from mail-wm1-f71.google.com (mail-wm1-f71.google.com [209.85.128.71]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-371-B89nv0TfOcmnB-VQwK3C6A-1; Thu, 02 Dec 2021 06:26:21 -0500 X-MC-Unique: B89nv0TfOcmnB-VQwK3C6A-1 Received: by mail-wm1-f71.google.com with SMTP id i131-20020a1c3b89000000b00337f92384e0so1529308wma.5 for ; Thu, 02 Dec 2021 03:26:21 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:message-id:date:mime-version:user-agent:subject :content-language:from:to:cc:references:organization:in-reply-to :content-transfer-encoding; bh=lDz7Gl7O/a6QxEzSyH8lRwP13RtbZV0kax667QfBu/c=; b=3D7XLWaIQJMI5FwIgXrfkQgYmkjhvvkIbQUyv13GUB7KwP6qKNcQHGhJYH+3EmkN9m c0THIg8rljIJJvJuTnVX8Qo0GX4XikckhnsS2taEigBYj1pulhSihj/5QqfPjJFNzzwI 45rdfqaBowD0LUJQCfrW/30ny87Blhh0A4cjeowlSBYTZJTD/wUjZULLH5h2pcJ2yTx8 X1eDAifNRAtJsMF9MnENx1VgMV+kWaLXA8vxsEK6OBJ/G4M2N+pK748XKym1iUvVLMc5 2Q+XrZeWGU5Gy4MQ8AlZhpyaoGo5XVoPdHxIrfA85kDnJ3G+6UVZn3TwKn0b+tAKY2CA E7xA== X-Gm-Message-State: AOAM532LQkuLJujoruEsnyfctym42fWinyjEcGHc222oCJCMuznMl+P8 A19DX907Zgt2Bjwp1D4T9S8QfUxMi0ddCvBVWzYERqgd5BW+M/0Dx4LYnkC2uM93cM0Ej1zt9lH FeLbmbS2k14/7SQcph18TDQ== X-Received: by 2002:a05:600c:202:: with SMTP id 2mr5681812wmi.134.1638444380197; Thu, 02 Dec 2021 03:26:20 -0800 (PST) X-Google-Smtp-Source: ABdhPJxMDm2ZHgmwsMQE5O2JaJyj6R5MG6Z9006cnJBbuG9m6i0+3MgupmDqot5W08j+xUfC3Vawig== X-Received: by 2002:a05:600c:202:: with SMTP id 2mr5681780wmi.134.1638444379976; Thu, 02 Dec 2021 03:26:19 -0800 (PST) Received: from ?IPV6:2003:d8:2f44:9200:3344:447e:353c:bf0b? (p200300d82f4492003344447e353cbf0b.dip0.t-ipconnect.de. [2003:d8:2f44:9200:3344:447e:353c:bf0b]) by smtp.gmail.com with ESMTPSA id j11sm2402688wrt.3.2021.12.02.03.26.19 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 02 Dec 2021 03:26:19 -0800 (PST) Message-ID: Date: Thu, 2 Dec 2021 12:26:18 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.2.0 Subject: Re: [kvm-unit-tests PATCH v1 2/2] s390x: firq: floating interrupt test Content-Language: en-US From: David Hildenbrand To: Claudio Imbrenda Cc: kvm@vger.kernel.org, Thomas Huth , Janosch Frank , Christian Borntraeger , Sebastian Mitterle , Halil Pasic , linux-s390@vger.kernel.org References: <20211202095843.41162-1-david@redhat.com> <20211202095843.41162-3-david@redhat.com> <20211202120113.2dd279a8@p-imbrenda> <95160439-2aa9-765f-9f06-16952e42a495@redhat.com> Organization: Red Hat In-Reply-To: <95160439-2aa9-765f-9f06-16952e42a495@redhat.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-s390@vger.kernel.org On 02.12.21 12:13, David Hildenbrand wrote: >>> +static void wait_for_sclp_int(void) >>> +{ >>> + /* Enable SCLP interrupts on this CPU only. */ >>> + ctl_set_bit(0, CTL0_SERVICE_SIGNAL); >>> + >>> + set_flag(1); >> >> why not just WRITE_ONCE/READ_ONCE? > > Because I shamelessly copied that from s390x/smp.c ;) Oh, and also because WRITE_ONCE/READ_ONCE are semantically the wrong thing to use: "Prevent the compiler from merging or refetching reads or writes. The compiler is also forbidden from reordering successive instances of READ_ONCE and WRITE_ONCE" We need memory barriers to prevent reordering with surrounding code. -- Thanks, David / dhildenb