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 45FDCC433EF for ; Wed, 6 Jul 2022 07:07:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=1gje+7JJywl8z+hojDQ/CdCFHPcNXeAmo9Z1tbQVDz0=; b=zsR8K3/A73gVakh7KHQr/D8sQr Ag5ElsbKUOOUdP+LgGGYBcJ/W8U3iKkuXLuV5xcIxgjVPCu5DuimhtiiDz49SPLsq8mDUVRpFvrXS wfMoGntw+J/wZVkjQ2r/HfmE0wOE5QlH7lSIgzDSBLkJXeLSLsCRPF4Gdyz26zbtroAZy8H/wtVT0 GelsWFGU23tUq4BO3NAOEF/qtkV1yxYG/bGI2CreZeoYg5oIhbaObzUP1H0SZMAYMdLTkFS/a0dpj AtsU+VMYcY3p+x2dmpt3m57ZRyXxrVvue296Ng4dLuuquGeK57Tn5Su4U6MaxSAGz4KKCCJb2yz9Y FeLfRJlA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1o8z8N-006xhc-MA; Wed, 06 Jul 2022 07:07:39 +0000 Received: from ams.source.kernel.org ([2604:1380:4601:e00::1]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1o8z5a-006vVv-ER for linux-nvme@lists.infradead.org; Wed, 06 Jul 2022 07:04:47 +0000 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id D3633B81AF2; Wed, 6 Jul 2022 07:04:44 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1095EC3411C; Wed, 6 Jul 2022 07:04:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1657091083; bh=yFTTCN8eLFI/FFSUip2r6VUaWUpwukK1oykDBvVFoaw=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=jvQpbiTHwHtxiL7mhpAUqPcIfklC3uMq+eSlq7Dn3j9ZoCfEt8bXAghrDvZr0IVL+ IVo2VVD6El337SyTT90L4wo/hIPFCt8NLQgPrX4IoEu6OyCSHbBsNvDzbu6ja4urNO b9ykds4BGL4/msxrju07lSQ9srOtvpaXTx1taFYM= Date: Wed, 6 Jul 2022 09:04:41 +0200 From: Greg Kroah-Hartman To: Christoph Hellwig Cc: Logan Gunthorpe , Jason Gunthorpe , linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org, linux-block@vger.kernel.org, linux-pci@vger.kernel.org, linux-mm@kvack.org, iommu@lists.linux-foundation.org, Stephen Bates , Dan Williams , Christian =?iso-8859-1?Q?K=F6nig?= , John Hubbard , Don Dutile , Matthew Wilcox , Daniel Vetter , Minturn Dave B , Jason Ekstrand , Dave Hansen , Xiong Jianxin , Bjorn Helgaas , Ira Weiny , Robin Murphy , Martin Oliveira , Chaitanya Kulkarni , Ralph Campbell , Bjorn Helgaas Subject: Re: [PATCH v7 20/21] PCI/P2PDMA: Introduce pci_mmap_p2pmem() Message-ID: References: <20220705161240.GB13721@lst.de> <20220705164315.GB14484@lst.de> <20220705165039.GB14566@lst.de> <1bd43ef7-0403-bd25-087c-d54d5af677e4@deltatee.com> <20220706065127.GA27132@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220706065127.GA27132@lst.de> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220706_000446_681336_CD9E750F X-CRM114-Status: GOOD ( 22.40 ) X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "Linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org On Wed, Jul 06, 2022 at 08:51:27AM +0200, Christoph Hellwig wrote: > On Tue, Jul 05, 2022 at 12:16:45PM -0600, Logan Gunthorpe wrote: > > The current version does it through a char device, but that requires > > creating a simple_fs and anon_inode for teardown on driver removal, plus > > a bunch of hooks through the driver that exposes it (NVMe, in this case) > > to set this all up. > > > > Christoph is suggesting a sysfs interface which could potentially avoid > > the anon_inode and all of the extra hooks. It has some significant > > benefits and maybe some small downsides, but I wouldn't describe it as > > horrid. > > Yeah, I don't think is is horrible, it fits in with the resource files > for the BARs, and solves a lot of problems. Greg, can you explain > what would be so bad about it? As you mention, you will have to pass different things down into sysfs in order for that to be possible. If it matches the resource files like we currently have today, that might not be that bad, but it still feels odd to me. Let's see an implementation and a Documentation/ABI/ entry first though. thanks, greg k-h