Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3C561C433FE for ; Sun, 12 Dec 2021 11:47:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230263AbhLLLrv (ORCPT ); Sun, 12 Dec 2021 06:47:51 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34720 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229464AbhLLLrt (ORCPT ); Sun, 12 Dec 2021 06:47:49 -0500 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 84685C061714; Sun, 12 Dec 2021 03:47:48 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.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=cdIWjpexE795gzuTbGkhPUpnRr/U2TeKiWDOHNiXINU=; b=DBuAHgfzGOIMRSDJohGgbB9HgK ghrV2KCPdFwOYiKPJbGZmSBlu830exEyDU1H933xIMmToosr9grTCGE55WJZij6cZJgiJ1q30Hz6n hZ10t4g0j/sD0EiJhnKSD6jRzu1/6oOpBcVGGwdhdZP63WKKmTkX5QTrHpV8qjjFHIi/X5QMWkaoG kknEssmq/uipXQiDMvDkVUnKo+GmhJFGjhExQwE0EWBz9jMfQIQFxVuyBDOWKu8J+hXb6Owf3uTdh 8Fl4Is3Mc1bjDe5u/B8VTKoy9i1C2ETLTUE3K71/BU8t21Bssus2/nA1qsleo4QX3UFxfJvaTfFhq xMZgWXeA==; Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1mwNKJ-00Bt8s-Ff; Sun, 12 Dec 2021 11:47:35 +0000 Date: Sun, 12 Dec 2021 11:47:35 +0000 From: Matthew Wilcox To: David Laight Cc: 'Tiezhu Yang' , Dave Young , Baoquan He , Vivek Goyal , Andrew Morton , "linux-arm-kernel@lists.infradead.org" , "linux-ia64@vger.kernel.org" , "linux-mips@vger.kernel.org" , "linuxppc-dev@lists.ozlabs.org" , "linux-riscv@lists.infradead.org" , "linux-sh@vger.kernel.org" , "x86@kernel.org" , "linux-fsdevel@vger.kernel.org" , "kexec@lists.infradead.org" , "linux-kernel@vger.kernel.org" , Xuefeng Li Subject: Re: [PATCH v2 0/2] kdump: simplify code Message-ID: References: <1639193588-7027-1-git-send-email-yangtiezhu@loongson.cn> <0c5cb37139af4f3e85cc2c5115d7d006@AcuMS.aculab.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <0c5cb37139af4f3e85cc2c5115d7d006@AcuMS.aculab.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Dec 11, 2021 at 05:53:46PM +0000, David Laight wrote: > From: Tiezhu Yang > > Sent: 11 December 2021 03:33 > > > > v2: > > -- add copy_to_user_or_kernel() in lib/usercopy.c > > -- define userbuf as bool type > > Instead of having a flag to indicate whether the buffer is user or kernel, > would it be better to have two separate buffer pointers. > One for a user space buffer, the other for a kernel space buffer. > Exactly one of the buffers should always be NULL. No. You should be using an iov_iter instead. See https://lore.kernel.org/all/Ya4bdB0UBJCZhUSo@casper.infradead.org/ for a start on this.