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=-9.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=ham 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 D39F6C00A89 for ; Fri, 30 Oct 2020 08:24:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 76C7622246 for ; Fri, 30 Oct 2020 08:24:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1604046273; bh=gSmXKcEPU74GTRAjfSumqviFvknWDQc7X1JOOAmSq+A=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=1g54dxoj80WvaS7qhI3YpcZgzr6M2XquUV98K+r4wGsQX3JkCbdebFtr3spxqU7kQ 3LgRymzstpo0a2W7Xlbb6UFpE3HUTdk4jIpbd4Wg6jgeufZVvxfwjGVm2OCnJUtJdz twZFvzvbuml6qOTOQHM2AEojOZcr9qvMa/xVY33k= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726055AbgJ3IYc (ORCPT ); Fri, 30 Oct 2020 04:24:32 -0400 Received: from mail.kernel.org ([198.145.29.99]:45660 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725355AbgJ3IYb (ORCPT ); Fri, 30 Oct 2020 04:24:31 -0400 Received: from localhost (83-86-74-64.cable.dynamic.v4.ziggo.nl [83.86.74.64]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 0A5E422253; Fri, 30 Oct 2020 08:24:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1604046270; bh=gSmXKcEPU74GTRAjfSumqviFvknWDQc7X1JOOAmSq+A=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Si1Xp4kz2nZiduJ6OnRI3808vnUeGlBGzEWnvohCTFWiL8OcNDVlCtzhiiSyo7uzA KWQToIUK6uyhXgmnpE6atZe+J3Vo7O9puJespbTMC9te+eVnaZjc+YQgbIsXwNys2L dfWEeyNDkAPCuWamjOc+NQFyjoaE2fmTeWcsQD0Q= Date: Fri, 30 Oct 2020 09:25:18 +0100 From: Greg KH To: Christian =?iso-8859-1?Q?K=F6nig?= Cc: Deepak R Varma , outreachy-kernel@googlegroups.com, Alex Deucher , David Airlie , Daniel Vetter , amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, melissa.srw@gmail.com, daniel.vetter@ffwll.ch Subject: Re: [Outreachy kernel] [PATCH] drm/amdgpu: use DEFINE_DEBUGFS_ATTRIBUTE with debugfs_create_file_unsafe() Message-ID: <20201030082518.GB1619669@kroah.com> References: <20201030032245.GA274478@my--box> <20201030071120.GA1493629@kroah.com> <20201030075716.GA6976@my--box> <5a7d8e8d-8db5-ff56-6448-3f1cefc11ef8@amd.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <5a7d8e8d-8db5-ff56-6448-3f1cefc11ef8@amd.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Oct 30, 2020 at 09:00:04AM +0100, Christian König wrote: > Am 30.10.20 um 08:57 schrieb Deepak R Varma: > > On Fri, Oct 30, 2020 at 08:11:20AM +0100, Greg KH wrote: > > > On Fri, Oct 30, 2020 at 08:52:45AM +0530, Deepak R Varma wrote: > > > > Using DEFINE_DEBUGFS_ATTRIBUTE macro with debugfs_create_file_unsafe() > > > > function in place of the debugfs_create_file() function will make the > > > > file operation struct "reset" aware of the file's lifetime. Additional > > > > details here: https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Flists.archive.carbon60.com%2Flinux%2Fkernel%2F2369498&data=04%7C01%7Cchristian.koenig%40amd.com%7Cddd7a6ac8164415a639708d87ca97004%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637396414464384011%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=o6GOHvMxNMuOPlC4nhDyURCHBLqfQZhYQq%2BiIMt3D3s%3D&reserved=0 > > > > > > > > Issue reported by Coccinelle script: > > > > scripts/coccinelle/api/debugfs/debugfs_simple_attr.cocci > > > > > > > > Signed-off-by: Deepak R Varma > > > > --- > > > > Please Note: This is a Outreachy project task patch. > > > > > > > > drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c | 20 ++++++++++---------- > > > > 1 file changed, 10 insertions(+), 10 deletions(-) > > > > > > > > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c > > > > index 2d125b8b15ee..f076b1ba7319 100644 > > > > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c > > > > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c > > > > @@ -1551,29 +1551,29 @@ static int amdgpu_debugfs_sclk_set(void *data, u64 val) > > > > return 0; > > > > } > > > > -DEFINE_SIMPLE_ATTRIBUTE(fops_ib_preempt, NULL, > > > > - amdgpu_debugfs_ib_preempt, "%llu\n"); > > > > +DEFINE_DEBUGFS_ATTRIBUTE(fops_ib_preempt, NULL, > > > > + amdgpu_debugfs_ib_preempt, "%llu\n"); > > > Are you sure this is ok? Do these devices need this additional > > > "protection"? Do they have the problem that these macros were written > > > for? > > > > > > Same for the other patches you just submitted here, I think you need to > > > somehow "prove" that these changes are necessary, checkpatch isn't able > > > to determine this all the time. > > Hi Greg, > > Based on my understanding, the current function debugfs_create_file() > > adds an overhead of lifetime managing proxy for such fop structs. This > > should be applicable to these set of drivers as well. Hence I think this > > change will be useful. > > Well since this is only created once per device instance I don't really care > about this little overhead. > > But what exactly is debugfs doing or not doing here? It is trying to save drivers from having debugfs files open that point to memory that can go away at any time. For graphics devices, I doubt that is the case. thanks, greg k-h