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=-0.7 required=3.0 tests=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 DCFF3C47254 for ; Fri, 1 May 2020 03:20:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C04F3206B8 for ; Fri, 1 May 2020 03:20:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728008AbgEADUa (ORCPT ); Thu, 30 Apr 2020 23:20:30 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40428 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727889AbgEADUa (ORCPT ); Thu, 30 Apr 2020 23:20:30 -0400 Received: from ZenIV.linux.org.uk (zeniv.linux.org.uk [IPv6:2002:c35c:fd02::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E9F23C035494; Thu, 30 Apr 2020 20:20:29 -0700 (PDT) Received: from viro by ZenIV.linux.org.uk with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1jUMDs-00FZCv-Qj; Fri, 01 May 2020 03:20:20 +0000 Date: Fri, 1 May 2020 04:20:20 +0100 From: Al Viro To: ira.weiny@intel.com Cc: linux-kernel@vger.kernel.org, Andrew Morton , Christian Koenig , Huang Rui , 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 , Dan Williams , 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, dri-devel@lists.freedesktop.org Subject: Re: [PATCH V1 09/10] arch/kmap: Define kmap_atomic_prot() for all arch's Message-ID: <20200501032020.GG23230@ZenIV.linux.org.uk> References: <20200430203845.582900-1-ira.weiny@intel.com> <20200430203845.582900-10-ira.weiny@intel.com> <20200501023734.GF23230@ZenIV.linux.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200501023734.GF23230@ZenIV.linux.org.uk> Sender: linux-csky-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-csky@vger.kernel.org On Fri, May 01, 2020 at 03:37:34AM +0100, Al Viro wrote: > On Thu, Apr 30, 2020 at 01:38:44PM -0700, ira.weiny@intel.com wrote: > > > -static inline void *kmap_atomic(struct page *page) > > +static inline void *kmap_atomic_prot(struct page *page, pgprot_t prot) > > { > > preempt_disable(); > > pagefault_disable(); > > if (!PageHighMem(page)) > > return page_address(page); > > - return kmap_atomic_high(page); > > + return kmap_atomic_high_prot(page, prot); > > } > > +#define kmap_atomic(page) kmap_atomic_prot(page, kmap_prot) > > OK, so it *was* just a bisect hazard - you return to original semantics > wrt preempt_disable()... FWIW, how about doing the following: just before #5/10 have a patch that would touch only microblaze, ppc and x86 splitting their kmap_atomic_prot() into an inline helper + kmap_atomic_high_prot(). Then your #5 would leave their kmap_atomic_prot() as-is (it would use kmap_atomic_prot_high() instead). The rest of the series plays out pretty much the same way it does now, and wrappers on those 3 architectures would go away when an identical generic one is introduced in this commit (#9/10). AFAICS, that would avoid the bisect hazard and might even end up with less noise in the patches...