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=-6.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SIGNED_OFF_BY,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 50F38C433E1 for ; Wed, 19 Aug 2020 19:39:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 34E1C2083B for ; Wed, 19 Aug 2020 19:39:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1597865949; bh=DxbS27PjcrGq47Jy2vOo4fq71i7SBBqm9acMLvSGxHA=; h=Date:From:To:Subject:In-Reply-To:Reply-To:List-ID:From; b=jtlWrMbSPhBnAtsjcwIFXQhtdKDNlhXxmuwBdi18BR68lso0OWNno5SzXIyIoQ/Zs y4D5moeQgT0Oe14EHUpVo+5PS2Urdv1onUd944FpCTtXPBWPmoiZR4yk6xXQuyuRYQ HFT4A/hBFQJLC5RWXg89McGzQNMmmL3nR3Dz7wXM= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726729AbgHSTjI (ORCPT ); Wed, 19 Aug 2020 15:39:08 -0400 Received: from mail.kernel.org ([198.145.29.99]:49152 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726466AbgHSTjH (ORCPT ); Wed, 19 Aug 2020 15:39:07 -0400 Received: from localhost.localdomain (c-73-231-172-41.hsd1.ca.comcast.net [73.231.172.41]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 9CA08207BB; Wed, 19 Aug 2020 19:39:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1597865946; bh=DxbS27PjcrGq47Jy2vOo4fq71i7SBBqm9acMLvSGxHA=; h=Date:From:To:Subject:In-Reply-To:From; b=PaNNzIE2SBzinZaOKckMxMr020dXpzS0v0gril98Xh/NEbdeqKKLAelOfLwuJa33I /cWDYJ4AATKBlDXtPBTnEOPyz2Xqndd7CrysMmvwwHiryrgV/EQtOmCP+ubEU+OLhj fedKocMgR0tPKC3D8jxk86aJOrx7r+tSDHtokU2c= Date: Wed, 19 Aug 2020 12:39:06 -0700 From: Andrew Morton To: dan.j.williams@intel.com, ira.weiny@intel.com, mm-commits@vger.kernel.org, vishal.l.verma@intel.com, william.kucharski@oracle.com Subject: + memremap-convert-devmap-static-branch-to-incdec.patch added to -mm tree Message-ID: <20200819193906.w1nj95HjC%akpm@linux-foundation.org> In-Reply-To: <20200814172939.55d6d80b6e21e4241f1ee1f3@linux-foundation.org> User-Agent: s-nail v14.8.16 Sender: mm-commits-owner@vger.kernel.org Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org The patch titled Subject: mm/memremap.c: convert devmap static branch to {inc,dec} has been added to the -mm tree. Its filename is memremap-convert-devmap-static-branch-to-incdec.patch This patch should soon appear at https://ozlabs.org/~akpm/mmots/broken-out/memremap-convert-devmap-static-branch-to-incdec.patch and later at https://ozlabs.org/~akpm/mmotm/broken-out/memremap-convert-devmap-static-branch-to-incdec.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next and is updated there every 3-4 working days ------------------------------------------------------ From: Ira Weiny Subject: mm/memremap.c: convert devmap static branch to {inc,dec} While reviewing Protection Key Supervisor support it was pointed out that using a counter to track static branch enable was an anti-pattern which was better solved using the provided static_branch_{inc,dec} functions.[1] Fix up devmap_managed_key to work the same way. Also this should be safer because there is a very small (very unlikely) race when multiple callers try to enable at the same time. [1] https://lore.kernel.org/lkml/20200714194031.GI5523@worktop.programming.kicks-ass.net/ Link: https://lkml.kernel.org/r/20200810235319.2796597-1-ira.weiny@intel.com Signed-off-by: Ira Weiny Reviewed-by: William Kucharski Cc: Dan Williams Cc: Vishal Verma Signed-off-by: Andrew Morton --- mm/memremap.c | 7 ++----- 1 file changed, 2 insertions(+), 5 deletions(-) --- a/mm/memremap.c~memremap-convert-devmap-static-branch-to-incdec +++ a/mm/memremap.c @@ -40,12 +40,10 @@ EXPORT_SYMBOL_GPL(memremap_compat_align) #ifdef CONFIG_DEV_PAGEMAP_OPS DEFINE_STATIC_KEY_FALSE(devmap_managed_key); EXPORT_SYMBOL(devmap_managed_key); -static atomic_t devmap_managed_enable; static void devmap_managed_enable_put(void) { - if (atomic_dec_and_test(&devmap_managed_enable)) - static_branch_disable(&devmap_managed_key); + static_branch_dec(&devmap_managed_key); } static int devmap_managed_enable_get(struct dev_pagemap *pgmap) @@ -56,8 +54,7 @@ static int devmap_managed_enable_get(str return -EINVAL; } - if (atomic_inc_return(&devmap_managed_enable) == 1) - static_branch_enable(&devmap_managed_key); + static_branch_inc(&devmap_managed_key); return 0; } #else _ Patches currently in -mm which might be from ira.weiny@intel.com are memremap-convert-devmap-static-branch-to-incdec.patch mm-highmem-clean-up-endif-comments.patch