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 F3486C5479D for ; Wed, 11 Jan 2023 16:29:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238622AbjAKQ2Q (ORCPT ); Wed, 11 Jan 2023 11:28:16 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36602 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234899AbjAKQ1z (ORCPT ); Wed, 11 Jan 2023 11:27:55 -0500 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 424AF1DF0D for ; Wed, 11 Jan 2023 08:25:05 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1673454304; h=from:from:reply-to:subject:subject:date:date:message-id:message-id:to: cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=KxBHdaiEAq2LsScflLkdFvYTtC4L7dZmM1H1mv+PG5k=; b=e1JDZ0zvEiYtJxd2PNBpRoRX36SRgcMaaqPaNLqj1MoyTf8S8BKeIZ9rijqtDQVC2ixkA7 /cZ9sWFwdgXl7iEY+hGHwYjqR3ZmH8EtGGkKHaT84YOLfTw5BZU9NqTNdfF8M+z+CNQHLk EDItKr2obskEdoW22cZg5bcWQQ0fxU8= Received: from mimecast-mx02.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-5-86uM21hhPZONYQ_5UmZHIw-1; Wed, 11 Jan 2023 11:25:03 -0500 X-MC-Unique: 86uM21hhPZONYQ_5UmZHIw-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 7E8373C0F22C; Wed, 11 Jan 2023 16:25:02 +0000 (UTC) Received: from warthog.procyon.org.uk (unknown [10.33.36.87]) by smtp.corp.redhat.com (Postfix) with ESMTP id 626DE40C1060; Wed, 11 Jan 2023 16:25:00 +0000 (UTC) Organization: Red Hat UK Ltd. Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 3798903 From: David Howells In-Reply-To: <2431994.1673453386@warthog.procyon.org.uk> References: <2431994.1673453386@warthog.procyon.org.uk> <20221226103309.953112-3-houtao@huaweicloud.com> <20221226103309.953112-1-houtao@huaweicloud.com> Cc: dhowells@redhat.com, Hou Tao , linux-cachefs@redhat.com, Jeff Layton , linux-erofs@lists.ozlabs.org, linux-kernel@vger.kernel.org, Jingbo Xu , houtao1@huawei.com Subject: Re: [PATCH v2 2/2] fscache: Add the missing smp_mb__after_atomic() before wake_up_bit() MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-ID: <2432455.1673454299.1@warthog.procyon.org.uk> Date: Wed, 11 Jan 2023 16:24:59 +0000 Message-ID: <2432456.1673454299@warthog.procyon.org.uk> X-Scanned-By: MIMEDefang 3.1 on 10.11.54.2 To: unlisted-recipients:; (no To-header on input) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org David Howells wrote: > What two values are you ordering? > > If we're using this to create a critical section, then yes, we would need a > barrier to order the changes inside the critical section before changing the > memory location that forms the lock - but this is not a critical section. Actually, that said, the ordering is probably between the bit being cleared and the task state. David