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=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable 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 DD9EFC5519C for ; Mon, 27 Apr 2020 01:16:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BA3FD206A5 for ; Mon, 27 Apr 2020 01:16:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726429AbgD0BQd (ORCPT ); Sun, 26 Apr 2020 21:16:33 -0400 Received: from mga11.intel.com ([192.55.52.93]:62678 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726323AbgD0BQc (ORCPT ); Sun, 26 Apr 2020 21:16:32 -0400 IronPort-SDR: Lv/v2Jhj0NyWAobklZlghw3MydTkknmxfhC7JeS1RSQhe+MFITHVsWvc2aHAnd5si+epKjfCQu IEveEu/quQnw== X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga001.jf.intel.com ([10.7.209.18]) by fmsmga102.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 26 Apr 2020 18:16:31 -0700 IronPort-SDR: ZrrKsQ6Zur3/bE2CO6sc6Wdv34dqrhqrjSlpkUGUwoboNwAHWFqd68hpZ33zjqX/g7EQHldNW4 L627f0bj0fUw== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.73,321,1583222400"; d="scan'208";a="336090274" Received: from iweiny-desk2.sc.intel.com ([10.3.52.147]) by orsmga001.jf.intel.com with ESMTP; 26 Apr 2020 18:16:31 -0700 Date: Sun, 26 Apr 2020 18:16:30 -0700 From: Ira Weiny To: Christoph Hellwig Cc: linux-kernel@vger.kernel.org, Andrew Morton , Dan Williams , Thomas Bogendoerfer , "James E.J. Bottomley" , Helge Deller , Benjamin Herrenschmidt , Paul Mackerras , "David S. Miller" , Thomas Gleixner , Ingo Molnar , Borislav Petkov , x86@kernel.org, "H. Peter Anvin" , Dave Hansen , Andy Lutomirski , Peter Zijlstra , Chris Zankel , Max Filippov , linux-snps-arc@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-csky@vger.kernel.org, linux-mips@vger.kernel.org, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, sparclinux@vger.kernel.org, linux-xtensa@linux-xtensa.org Subject: Re: [PATCH 4/5] arch/kmap_atomic: Consolidate duplicate code Message-ID: <20200427011630.GC135929@iweiny-DESK2.sc.intel.com> References: <20200426055406.134198-1-ira.weiny@intel.com> <20200426055406.134198-5-ira.weiny@intel.com> <20200426072642.GB22024@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200426072642.GB22024@infradead.org> User-Agent: Mutt/1.11.1 (2018-12-01) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Apr 26, 2020 at 12:26:42AM -0700, Christoph Hellwig wrote: > > diff --git a/arch/arc/mm/highmem.c b/arch/arc/mm/highmem.c > > index 4db13a6b9f3b..1cae4b911a33 100644 > > --- a/arch/arc/mm/highmem.c > > +++ b/arch/arc/mm/highmem.c > > @@ -53,11 +53,10 @@ void *kmap_atomic(struct page *page) > > { > > int idx, cpu_idx; > > unsigned long vaddr; > > + void *addr = kmap_atomic_fast(page); > > > > - preempt_disable(); > > - pagefault_disable(); > > - if (!PageHighMem(page)) > > - return page_address(page); > > + if (addr) > > + return addr; > > Wouldn't it make sense to just move kmap_atomic itelf to common code, > and call out to a kmap_atomic_high for the highmem case, following the > scheme in kmap? > Sure I do like that symmetry between the calls. > > Same for the unmap side. FWIW that would simply be renaming __kunmap_atomic() to kunmap_atomic_high() > > That might require to support > kmap_atomic_prot everywhere first, which sounds like a really good > idea anyway, and would avoid the need for strange workaround in drm. Having a kmap_atomic_prot() seems like a good idea. But I'm not exactly sure why CONFIG_x86 is being called out specifically in the DRM code? Ira