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=-8.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 EB908C388F9 for ; Thu, 19 Nov 2020 20:53:46 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id 175072100A for ; Thu, 19 Nov 2020 20:53:45 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="EBwaYbY+" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 175072100A Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:43372 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1kfqw4-0007sw-ON for qemu-devel@archiver.kernel.org; Thu, 19 Nov 2020 15:53:44 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:60132) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kfqdb-0003eq-JL for qemu-devel@nongnu.org; Thu, 19 Nov 2020 15:34:43 -0500 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:56925) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1kfqdZ-0000ZF-9F for qemu-devel@nongnu.org; Thu, 19 Nov 2020 15:34:38 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1605818075; 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: in-reply-to:in-reply-to:references:references; bh=P6DVv6OX8ZbFqpMeWwlCSI84qBvD/MtgVX6Ju5UVVdI=; b=EBwaYbY+hWQKCFlrC+JJq9SaZnNQ1u0AbP22F+bDRUoj5VtJvLJFEUo0RkjZ3tiCkONVF/ tEtHM4sBrgCq+hglM1t+sxoSa2PequMeT3ZfFWBCyBHlxIsX4c5D9X/kHK7UI3glj6kY83 xT3NHBZVq8eZYAlcBSH1kKoxp+ziTBY= Received: from mail-qk1-f200.google.com (mail-qk1-f200.google.com [209.85.222.200]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-486-A4wuVSh6NomoX4UAL_q_1w-1; Thu, 19 Nov 2020 15:34:33 -0500 X-MC-Unique: A4wuVSh6NomoX4UAL_q_1w-1 Received: by mail-qk1-f200.google.com with SMTP id q25so6021630qkm.17 for ; Thu, 19 Nov 2020 12:34:33 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=P6DVv6OX8ZbFqpMeWwlCSI84qBvD/MtgVX6Ju5UVVdI=; b=rj+A8wPdI9SURm71NiltgEPaDp9MYIE0hbVilgFXBTiPLSlNaewgFlyGeVgjzC/eFz fs8xNdWBvY2r674D5+5/ZePWnLhj67mW2FMOPmITmxMogF0y79UqPBRyIIu/ZplZVngW afA2A3ZF/FJpEiidJWcwibF/MbRK1h3w8bTrbOvdvkZKU++R9e4v4wVz+8i+eVPnNhYa O4iYYW6udgldYx3RVt3ZIerz4hja1cyrPyy0aA9h2fzxjT6Oeu+pL7vyW155RkbOzFCe BZCt+/H+B3jxg3CCE4OUGwPkE0+gwu46M8aiy8KcB/Dprl+v+h6y8LcUdA4KyH8SsQ3g ZBLA== X-Gm-Message-State: AOAM531cQMJFaBJUMrb7YYhBPcOoUI9/OhN/s+TMHcvyl7DzjNxp0M+h TP4b9kRVO9CA3+nv4P2xmeZnZSHARtOQktkPKNDnLsiAl2Mrqf9/GAjZbdRSZqzy9EjnBcD8bzZ BqYe8Xb0g2dbRv9g= X-Received: by 2002:ac8:6ec5:: with SMTP id f5mr12727672qtv.56.1605818073099; Thu, 19 Nov 2020 12:34:33 -0800 (PST) X-Google-Smtp-Source: ABdhPJwQU44E49+wrEjimavw5xan1K1Hhl4DQRI1RDna6kl0+ym/ZkbN3/W0/9GpVQ74xdW1QQHjTw== X-Received: by 2002:ac8:6ec5:: with SMTP id f5mr12727637qtv.56.1605818072828; Thu, 19 Nov 2020 12:34:32 -0800 (PST) Received: from xz-x1 (bras-vprn-toroon474qw-lp130-20-174-93-89-196.dsl.bell.ca. [174.93.89.196]) by smtp.gmail.com with ESMTPSA id z6sm600358qti.88.2020.11.19.12.34.31 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 19 Nov 2020 12:34:31 -0800 (PST) Date: Thu, 19 Nov 2020 15:34:30 -0500 From: Peter Xu To: David Hildenbrand Subject: Re: [PATCH v1 6/9] softmmu/physmem: Don't use atomic operations in ram_block_discard_(disable|require) Message-ID: <20201119203430.GA32525@xz-x1> References: <20201119153918.120976-1-david@redhat.com> <20201119153918.120976-7-david@redhat.com> MIME-Version: 1.0 In-Reply-To: <20201119153918.120976-7-david@redhat.com> Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=peterx@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Received-SPF: pass client-ip=63.128.21.124; envelope-from=peterx@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_H4=0.001, RCVD_IN_MSPIKE_WL=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: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Pankaj Gupta , Wei Yang , "Michael S. Tsirkin" , qemu-devel@nongnu.org, "Dr . David Alan Gilbert" , Auger Eric , Alex Williamson , teawater , Igor Mammedov , Paolo Bonzini , Luiz Capitulino , Marek Kedzierski Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Thu, Nov 19, 2020 at 04:39:15PM +0100, David Hildenbrand wrote: > int ram_block_discard_disable(bool state) > { > - int old; > + int ret = 0; > > + ram_block_discard_disable_mutex_lock(); > if (!state) { > - qatomic_dec(&ram_block_discard_disabled); > - return 0; > + ram_block_discard_disablers--; > + } else if (!ram_block_discard_requirers) { > + ram_block_discard_disablers++; > + } else { > + ret = -EBUSY; > } I would make things even easier by: if (ram_block_discard_is_required()) { return -EBUSY; } if (state) { ram_block_discard_disablers++; } else { ram_block_discard_disablers--; } But I think it's kind of nitpicking. :) Reviewed-by: Peter Xu Thanks for writing this patch. -- Peter Xu