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=-5.3 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 3FB2AC433E4 for ; Tue, 14 Jul 2020 19:40:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1E3BC224F4 for ; Tue, 14 Jul 2020 19:40:52 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="hfQoOcG+" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730063AbgGNTku (ORCPT ); Tue, 14 Jul 2020 15:40:50 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46880 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729702AbgGNTks (ORCPT ); Tue, 14 Jul 2020 15:40:48 -0400 Received: from merlin.infradead.org (merlin.infradead.org [IPv6:2001:8b0:10b:1231::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8F50BC061755; Tue, 14 Jul 2020 12:40:48 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=A7QakhpbDS7UpMv5+nU5KcUWNAdeAaqYrQ/G09rIDaM=; b=hfQoOcG+Pzg8dmu3eJSSuTU6l1 IOJF9Ygv/Ir6H4jax9Vk0necvIXLuIFoc8RghaSIpMO2o90p3Kq+v8gmgX+JBiM2dUtjNrfgeLaIE NygcPnxNWGIDt8TfeoiZjI3culu/1+/kakxLwczxNW6ZtWxyqh0zsIiYqlLORazVknTBLLZhmFarB oxjQNqBBHr+/xhoC//cla5A+xlCy3cwKDZPEBcjywqGKy+NS8coxnvKAin3/6zvC+y5ORIiiFWrL7 8niS3yPRXFTMnawEHXnE3kmKOZa2Rjy2EMpWfjQklgfuiYZLSLOyu0KH3mh9FihtfRDQMzFs7CKzb bKC+acMQ==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=worktop.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1jvQn3-0003Xv-HT; Tue, 14 Jul 2020 19:40:33 +0000 Received: by worktop.programming.kicks-ass.net (Postfix, from userid 1000) id 9D32E9817E0; Tue, 14 Jul 2020 21:40:31 +0200 (CEST) Date: Tue, 14 Jul 2020 21:40:31 +0200 From: Peter Zijlstra To: Ira Weiny Cc: Thomas Gleixner , Ingo Molnar , Borislav Petkov , Andy Lutomirski , x86@kernel.org, Dave Hansen , Dan Williams , Vishal Verma , Andrew Morton , Fenghua Yu , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-nvdimm@lists.01.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org Subject: Re: [RFC PATCH 11/15] memremap: Add zone device access protection Message-ID: <20200714194031.GI5523@worktop.programming.kicks-ass.net> References: <20200714070220.3500839-1-ira.weiny@intel.com> <20200714070220.3500839-12-ira.weiny@intel.com> <20200714084057.GP10769@hirez.programming.kicks-ass.net> <20200714191047.GE3008823@iweiny-DESK2.sc.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200714191047.GE3008823@iweiny-DESK2.sc.intel.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jul 14, 2020 at 12:10:47PM -0700, Ira Weiny wrote: > On Tue, Jul 14, 2020 at 10:40:57AM +0200, Peter Zijlstra wrote: > > That's an anti-pattern vs static_keys, I'm thinking you actually want > > static_key_slow_{inc,dec}() instead of {enable,disable}(). > > Thanks. I'll go read the doc for those as I'm not familiar with them. Look for static_branch_{inc,dec} in include/linux/jump_label.h, it basically does the refcount thing you need and does the actual transition on the 0->1 and 1->0 transitions.