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=-6.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no 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 8D1B0C07E98 for ; Sat, 3 Jul 2021 04:49:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6C6B36142B for ; Sat, 3 Jul 2021 04:49:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229976AbhGCEwY (ORCPT ); Sat, 3 Jul 2021 00:52:24 -0400 Received: from mail.kernel.org ([198.145.29.99]:43264 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229461AbhGCEwX (ORCPT ); Sat, 3 Jul 2021 00:52:23 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 5D3EA613C9; Sat, 3 Jul 2021 04:49:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1625287788; bh=mGZyq3JSQsP4iGY+awgr6y4sM3v63gkuGZxGC42AQJU=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Qrxe9zLtWfzjmDX9BHre42DOiJuHuM8V5xGwohED6e4CSZ4K38p9MJQTvcYGjI8xM jjQwyVhvc+UfyH/3tgj0L7urGLB/lTsYjDjozqus5pLbOH67LBRr4aFig8yekeG3tN u5XWPLwsOrr8kSRTc1SXwzg9ImErPRTOm9W614To= Date: Sat, 3 Jul 2021 06:49:46 +0200 From: Greg KH To: Luis Chamberlain Cc: tj@kernel.org, shuah@kernel.org, akpm@linux-foundation.org, rafael@kernel.org, davem@davemloft.net, kuba@kernel.org, ast@kernel.org, andriin@fb.com, daniel@iogearbox.net, atenart@kernel.org, alobakin@pm.me, weiwan@google.com, ap420073@gmail.com, jeyu@kernel.org, ngupta@vflare.org, sergey.senozhatsky.work@gmail.com, minchan@kernel.org, axboe@kernel.dk, mbenes@suse.com, jpoimboe@redhat.com, tglx@linutronix.de, keescook@chromium.org, jikos@kernel.org, rostedt@goodmis.org, peterz@infradead.org, linux-block@vger.kernel.org, netdev@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 4/4] test_sysfs: demonstrate deadlock fix Message-ID: References: <20210703004632.621662-1-mcgrof@kernel.org> <20210703004632.621662-5-mcgrof@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210703004632.621662-5-mcgrof@kernel.org> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jul 02, 2021 at 05:46:32PM -0700, Luis Chamberlain wrote: > +#define MODULE_DEVICE_ATTR_FUNC_STORE(_name) \ > +static ssize_t module_ ## _name ## _store(struct device *dev, \ > + struct device_attribute *attr, \ > + const char *buf, size_t len) \ > +{ \ > + ssize_t __ret; \ > + if (!try_module_get(THIS_MODULE)) \ > + return -ENODEV; \ > + __ret = _name ## _store(dev, attr, buf, len); \ > + module_put(THIS_MODULE); \ > + return __ret; \ > +} As I have pointed out before, doing try_module_get(THIS_MODULE) is racy and should not be added back to the kernel tree. We got rid of many instances of this "bad pattern" over the years, please do not encourage it to be added back as others will somehow think that it correct code. I'll go over the rest of this after 5.14-rc1 is out, am busy until then. thanks, greg k-h