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=-6.8 required=3.0 tests=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=unavailable 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 985B4C54FCB for ; Mon, 20 Apr 2020 11:39:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7665B214AF for ; Mon, 20 Apr 2020 11:39:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1587382779; bh=ayEwL0nLQ4QNklqralna2ArCsYIcKq41Dq3so3Ua300=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=sO2Fo3mfaTLMkz85kJEh0MNaJxn0gBd/EDVn35knVSimOoqN2H0CRZjOYgdQsUUFy uSlX8+k30FkCvaxcJ/aUIDupzTkPx0A9DIye/xMbV3VzlI1zaQky13MBgO/NcitxKC 4pMYTYVFkOU83FTx+nw2oUCq+k3RmvmQZGF65mZk= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726416AbgDTLji (ORCPT ); Mon, 20 Apr 2020 07:39:38 -0400 Received: from mail.kernel.org ([198.145.29.99]:41974 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726277AbgDTLji (ORCPT ); Mon, 20 Apr 2020 07:39:38 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (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 645AC206D4; Mon, 20 Apr 2020 11:39:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1587382777; bh=ayEwL0nLQ4QNklqralna2ArCsYIcKq41Dq3so3Ua300=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=YKyAxxq7yd26pECXoTlbjKqMWFkRdNhgDxZ9xKhdL1f8UpX7ouB4svzDyfpIC47Il N3uYBGimgkrH/iU2TCsj8b8bg1iDycwlQWtGMUpTeM9iwNLGvtsOqDFWeatnd54TY1 fZstqWPRni2bIUoWgNa2Fn3AklEIsfQd4XlGZFXk= Date: Mon, 20 Apr 2020 13:39:35 +0200 From: Greg KH To: Luis Chamberlain Cc: axboe@kernel.dk, viro@zeniv.linux.org.uk, bvanassche@acm.org, rostedt@goodmis.org, mingo@redhat.com, jack@suse.cz, ming.lei@redhat.com, nstange@suse.de, akpm@linux-foundation.org, mhocko@suse.com, yukuai3@huawei.com, linux-block@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 08/10] blktrace: add checks for created debugfs files on setup Message-ID: <20200420113935.GD3906674@kroah.com> References: <20200419194529.4872-1-mcgrof@kernel.org> <20200419194529.4872-9-mcgrof@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200419194529.4872-9-mcgrof@kernel.org> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Apr 19, 2020 at 07:45:27PM +0000, Luis Chamberlain wrote: > Even though debugfs can be disabled, enabling BLK_DEV_IO_TRACE will > select DEBUG_FS, and blktrace exposes an API which userspace uses > relying on certain files created in debugfs. If files are not created > blktrace will not work correctly, so we do want to ensure that a > blktrace setup creates these files properly, and otherwise inform > userspace. > > Signed-off-by: Luis Chamberlain > --- > kernel/trace/blktrace.c | 8 +++++--- > 1 file changed, 5 insertions(+), 3 deletions(-) > > diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c > index 9cc0153849c3..fc32a8665ce8 100644 > --- a/kernel/trace/blktrace.c > +++ b/kernel/trace/blktrace.c > @@ -552,17 +552,19 @@ static int blk_trace_create_debugfs_files(struct blk_user_trace_setup *buts, > struct dentry *dir, > struct blk_trace *bt) > { > - int ret = -EIO; > - > bt->dropped_file = debugfs_create_file("dropped", 0444, dir, bt, > &blk_dropped_fops); > + if (!bt->dropped_file) > + return -ENOMEM; No, this is wrong, please do not ever check the return value of a debugfs call. See the zillions of patches I've been doing to the kernel for this type of thing over the past year for examples of why. the code is fine as-is. greg k-h