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=-6.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 47B08C4332B for ; Sat, 4 Apr 2020 16:35:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1605F2063A for ; Sat, 4 Apr 2020 16:35:38 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="hUY1lkeI" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726315AbgDDQfa (ORCPT ); Sat, 4 Apr 2020 12:35:30 -0400 Received: from mail-lj1-f195.google.com ([209.85.208.195]:33596 "EHLO mail-lj1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726207AbgDDQf3 (ORCPT ); Sat, 4 Apr 2020 12:35:29 -0400 Received: by mail-lj1-f195.google.com with SMTP id f20so10203338ljm.0; Sat, 04 Apr 2020 09:35:28 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=TcZGIpZFtsXQnB9IM08ZO9Vrk1h6ZXgf7qgWlNa11hY=; b=hUY1lkeI80CHymemQMT2uF4IhmhhZhgY8dFrQIX+4laKtyHJNVGCd10YpYGNBDmf8d LKOLEObwgKE9KfsVT2Gk5vnQxkov3L7FkCbemeaM2p600g2ZXHDfFa4Tm9e1jx5uwjxX BHyug1lXYg9GJAGNttowFSA33mKP1QwLnV3CU+2GZoxId1KgHR9ctXERL06I+QEnQd03 szDsKjH6W1VSKRvxtxzqBvFAftKjcnWUcWtxsqoFZwiSyQq7C1F62cDj3/bJu+yyWpSd xzK5hwXFV7H3LS4QZUZQHKfwp8VTSf+aDJoaUlaw42XWugoGCA1ebLpAZCLZ3IZtiaOx 0bUg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=TcZGIpZFtsXQnB9IM08ZO9Vrk1h6ZXgf7qgWlNa11hY=; b=F4x0zhTINI4XOGQzoWYDf8hnbH09/HDUmjCFTz/EDaiGdZHRhuSxFwbGfFv5/r2pWe Q1py+ZUNiADLOL963hKw2wQSqJvLMKBzpaYWcw/8BVu9rU1mVRa+UXAglEOR8GVldkA1 M+wK2fPP6AISxAKyOty6crJ8P0e60LeZZaDljXjG+UdJ1qAUoSJAn/qITBx1QEpLqIHz wacjJk/LpSFrjHoUcNnfKuqbaHyaPxbMdwWajLEuTVK/Jug43CEKDG0IrujSht45+Taa 6UzrYAErDW5mOHPQtJT+FkaGh2om4ZngZGVkgEGW+RbqgBOdm07BQ14wxCexSMU42nbz 6IxA== X-Gm-Message-State: AGi0PuYwRPCq59j691ZZKUn+yzZl1aYAZA9tgQS/D4/2gpEBNv4ZLM8Z FZRcewT2+w8zfl/gaS4CPNqTJCubC4Bbudtkud4= X-Google-Smtp-Source: APiQypIe+DtLDZ6Yy6a7w+4neV8cfXmY7x+lCE8hWWOYcjUAAb0I8sPBi8KtcYImnj02TLzzvlScEeSl45FEjsLC5Z0= X-Received: by 2002:a2e:4942:: with SMTP id b2mr8092892ljd.135.1586018127540; Sat, 04 Apr 2020 09:35:27 -0700 (PDT) MIME-Version: 1.0 References: <20200404141827.26255-1-ap420073@gmail.com> <20200404155040.GC1476305@kroah.com> In-Reply-To: <20200404155040.GC1476305@kroah.com> From: Taehee Yoo Date: Sun, 5 Apr 2020 01:35:16 +0900 Message-ID: Subject: Re: [PATCH net v2 1/3] class: add class_has_file_ns() helper function To: Greg KH Cc: David Miller , Jakub Kicinski , rafael@kernel.org, j.vosburgh@gmail.com, vfalico@gmail.com, Andy Gospodarek , Netdev , LKML , mitch.a.williams@intel.com Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, 5 Apr 2020 at 00:50, Greg KH wrote: > Hi Greg, Thank you for your review! > On Sat, Apr 04, 2020 at 02:18:27PM +0000, Taehee Yoo wrote: > > The new helper function is to check whether the class file is existing > > or not. This function will be used by networking stack to > > check "/sys/class/net/*" file. > > > > Reported-by: syzbot+830c6dbfc71edc4f0b8f@syzkaller.appspotmail.com > > Fixes: b76cdba9cdb2 ("[PATCH] bonding: add sysfs functionality to bonding (large)") > > Signed-off-by: Taehee Yoo > > --- > > > > v1 -> v2: > > - Implement class_has_file_ns() instead of class_find_and_get_file_ns(). > > - Change headline. > > - Add kernel documentation comment. > > > > drivers/base/class.c | 22 ++++++++++++++++++++++ > > include/linux/device/class.h | 3 ++- > > 2 files changed, 24 insertions(+), 1 deletion(-) > > > > diff --git a/drivers/base/class.c b/drivers/base/class.c > > index bcd410e6d70a..a2f2787f6aa7 100644 > > --- a/drivers/base/class.c > > +++ b/drivers/base/class.c > > @@ -105,6 +105,28 @@ void class_remove_file_ns(struct class *cls, const struct class_attribute *attr, > > sysfs_remove_file_ns(&cls->p->subsys.kobj, &attr->attr, ns); > > } > > > > +/** > > + * class_has_file_ns - check whether file is existing or not > > + * @cls: the compatibility class > > + * @name: name to look for > > + * @ns: the namespace tag to use > > + */ > > +bool class_has_file_ns(struct class *cls, const char *name, > > + const void *ns) > > Why would you use this? And what happens if the file shows up, or goes > away, instantly after this call is made? > > This feels very broken. > Ah, I missed considering other usescases. If other users don't use locks, this function would return incorrect information. The problem seems to become from that this function calls kernfs_put(). Thanks a lot! Taehee Yoo