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 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 0B70CC433EF for ; Sun, 12 Dec 2021 11:48:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=zSPE915eI7c2wPtQPVur9PGE5IIz5y70uSkG6ot8X+U=; b=TtUen6/Lfmjp5y kZ0mh59vnI2bbQCH68xphAHE988v4kfKLVlEfUFXXH6ZQTn7dajtH3xW/ThrNuJDE5impjavzF2FV hfu6MzBfyajXP8o1kmW0kYKyg45psdRjF2/vlM8mvSTsV0nt0tUIxYENLLgBbe5Er08VaUlyWvyng try0VVHb91LW68vmPRln5KGqoMWEXMoAqD+NSNBgsxrM2AvXBpm4Zv9I2Z7oBPYuDUGaW4EDSKWF+ 0RJv9j4RLbHwoZu5e1q8vb+1FTzTlrs2esXP2yPnfGKMLGyQcwe/d45E32p1W80jv+csLAl6aT978 6N8mhPFuhQED8Y5kfSdw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1mwNKZ-006OZc-Ed; Sun, 12 Dec 2021 11:47:51 +0000 Received: from casper.infradead.org ([2001:8b0:10b:1236::1]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1mwNKN-006OWH-KW; Sun, 12 Dec 2021 11:47:39 +0000 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-Disposition: inline In-Reply-To: <0c5cb37139af4f3e85cc2c5115d7d006@AcuMS.aculab.com> X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.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. _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv