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=-3.8 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED 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 0E533C433DF for ; Tue, 14 Jul 2020 08:41:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DAAE021D6C for ; Tue, 14 Jul 2020 08:41:11 +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="wfr+9nwG" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726770AbgGNIlK (ORCPT ); Tue, 14 Jul 2020 04:41:10 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56508 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726354AbgGNIlK (ORCPT ); Tue, 14 Jul 2020 04:41:10 -0400 Received: from merlin.infradead.org (merlin.infradead.org [IPv6:2001:8b0:10b:1231::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C1297C061755; Tue, 14 Jul 2020 01:41:09 -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=7EYMAPkg0epsaMUyGWJdgDKUvk+AqT0tO9qkB/mcaeo=; b=wfr+9nwGB+CdzxX9LElESkKpwK 5k6vYKRmT9DWltVSjWYMZnlQ/I7lRShp5WfUSxuESbkpptjM1Zh51DEeu3IE2h70muDG6uMcqNOJs tbUiCnwFTFua/844sZg8NY3KOWNMYBopQOL65ye10DuSJEQrab2Owce2ZJPEvCdclI4nYahvmc+/m EAV1vZjgIkz6FI88PB18iJgnXx5oP3SGBVUT0ldkiYGCcd17mQCOx3Ky+cLShm+MxUZWkyYv8ysI/ pC8MiwAVFKfFJndnElLfvG/DprsK6kP6uqUIpq6f1xjuyLepg4kSLDczlLmAkx+6IjVFOvlyQchuw oZXIlvmQ==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1jvGUl-0006VI-Lv; Tue, 14 Jul 2020 08:40:59 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 8831E305C22; Tue, 14 Jul 2020 10:40:57 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 7393128B91072; Tue, 14 Jul 2020 10:40:57 +0200 (CEST) Date: Tue, 14 Jul 2020 10:40:57 +0200 From: Peter Zijlstra To: ira.weiny@intel.com 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: <20200714084057.GP10769@hirez.programming.kicks-ass.net> References: <20200714070220.3500839-1-ira.weiny@intel.com> <20200714070220.3500839-12-ira.weiny@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200714070220.3500839-12-ira.weiny@intel.com> 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 12:02:16AM -0700, ira.weiny@intel.com wrote: > +static pgprot_t dev_protection_enable_get(struct dev_pagemap *pgmap, pgprot_t prot) > +{ > + if (pgmap->flags & PGMAP_PROT_ENABLED && dev_page_pkey != PKEY_INVALID) { > + pgprotval_t val = pgprot_val(prot); > + > + mutex_lock(&dev_prot_enable_lock); > + dev_protection_enable++; > + /* Only enable the static branch 1 time */ > + if (dev_protection_enable == 1) > + static_branch_enable(&dev_protection_static_key); > + mutex_unlock(&dev_prot_enable_lock); > + > + prot = __pgprot(val | _PAGE_PKEY(dev_page_pkey)); > + } > + return prot; > +} > + > +static void dev_protection_enable_put(struct dev_pagemap *pgmap) > +{ > + if (pgmap->flags & PGMAP_PROT_ENABLED && dev_page_pkey != PKEY_INVALID) { > + mutex_lock(&dev_prot_enable_lock); > + dev_protection_enable--; > + if (dev_protection_enable == 0) > + static_branch_disable(&dev_protection_static_key); > + mutex_unlock(&dev_prot_enable_lock); > + } > +} That's an anti-pattern vs static_keys, I'm thinking you actually want static_key_slow_{inc,dec}() instead of {enable,disable}().