From patchwork Wed Jun 20 17:19:55 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jeff Mahoney X-Patchwork-Id: 10478015 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 98022601D7 for ; Wed, 20 Jun 2018 17:20:03 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 7BAAD28F32 for ; Wed, 20 Jun 2018 17:20:03 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 6FF6428F34; Wed, 20 Jun 2018 17:20:03 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00, MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 0C2C928F32 for ; Wed, 20 Jun 2018 17:20:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754185AbeFTRUA (ORCPT ); Wed, 20 Jun 2018 13:20:00 -0400 Received: from mx2.suse.de ([195.135.220.15]:43938 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754113AbeFTRUA (ORCPT ); Wed, 20 Jun 2018 13:20:00 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (charybdis-ext-too.suse.de [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id 9EDCEAC0C; Wed, 20 Jun 2018 17:19:58 +0000 (UTC) Subject: Re: [PATCH] btrfs: Fix a C compliance issue To: dsterba@suse.cz, Bart Van Assche , "nborisov@suse.com" , "dsterba@suse.com" , "clm@fb.com" , "jbacik@fb.com" , "linux-btrfs@vger.kernel.org" References: <20180615223659.32420-1-bart.vanassche@wdc.com> <838e73e8-e9b8-6075-1d69-79bc65c15b0c@suse.com> <20180618092633.GH24375@twin.jikos.cz> <14645aca-930b-2d7d-a7d6-6893f7cfcbbd@suse.com> <20180620165556.GF24375@twin.jikos.cz> From: Jeff Mahoney Openpgp: preference=signencrypt Message-ID: Date: Wed, 20 Jun 2018 13:19:55 -0400 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.13; rv:52.0) Gecko/20100101 Thunderbird/52.8.0 MIME-Version: 1.0 In-Reply-To: <20180620165556.GF24375@twin.jikos.cz> Content-Language: en-US Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP On 6/20/18 12:55 PM, David Sterba wrote: > On Wed, Jun 20, 2018 at 04:44:54PM +0000, Bart Van Assche wrote: >> On Mon, 2018-06-18 at 12:31 +0300, Nikolay Borisov wrote: >>> On 18.06.2018 12:26, David Sterba wrote: >>>> On Sat, Jun 16, 2018 at 01:28:13PM +0300, Nikolay Borisov wrote: >>>>> I'd rather not see more printk being added. Nothing prevents from having >>>>> the fmt string being passed to pr_info. >>>> >>>> So you mean to do >>>> >>>> + static const char fmt[] = "Btrfs loaded, crc32c=%s" >>>> + pr_info(fmt); >>> >>> Pretty much, something along the lines of >>> >>> pr_info(fmt, crc32c_impl). >>> >>> printk requires having the KERN_INFO in the format string, which I see >>> no point in doing, correct me if I'm wrong? >> >> You should know that what you proposed doesn't compile because pr_info() >> relies on string concatenation and hence requires that its first argument is >> a string constant instead of a const char pointer. Anyway, I will rework this >> patch such that it uses pr_info() instead of printk(). > > Right, the pr_info(fmt,...) does not compile. The closest version I got to is > below. It does not look pretty, but I can't think of a better version right > now. > > --- a/fs/btrfs/super.c > +++ b/fs/btrfs/super.c > @@ -2369,7 +2369,8 @@ static __cold void btrfs_interface_exit(void) > > static void __init btrfs_print_mod_info(void) > { > - static const char fmt[] = KERN_INFO "Btrfs loaded, crc32c=%s" > + static const char fmt1[] = "Btrfs loaded, crc32c="; > + static const char fmt2[] = > #ifdef CONFIG_BTRFS_DEBUG > ", debug=on" > #endif > @@ -2383,7 +2384,7 @@ static void __init btrfs_print_mod_info(void) > ", ref-verify=on" > #endif > "\n"; > - printk(fmt, crc32c_impl()); > + pr_info("%s%s%s", fmt1, crc32c_impl(), fmt2); > } > > static int __init init_btrfs_fs(void) The shed should be yellow. -Jeff diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c index 891cd2ed5dd4..57c9da0b459f 100644 --- a/fs/btrfs/super.c +++ b/fs/btrfs/super.c @@ -2375,21 +2375,20 @@ static __cold void btrfs_interface_exit(void) static void __init btrfs_print_mod_info(void) { - pr_info("Btrfs loaded, crc32c=%s" + pr_info("Btrfs loaded, crc32c=%s", crc32c_impl()); #ifdef CONFIG_BTRFS_DEBUG - ", debug=on" + pr_cont(", debug=on"); #endif #ifdef CONFIG_BTRFS_ASSERT - ", assert=on" + pr_cont(", assert=on"); #endif #ifdef CONFIG_BTRFS_FS_CHECK_INTEGRITY - ", integrity-checker=on" + pr_cont(", integrity-checker=on"); #endif #ifdef CONFIG_BTRFS_FS_REF_VERIFY - ", ref-verify=on" + pr_cont(", ref-verify=on") #endif - "\n", - crc32c_impl()); + pr_cont("\n"); } static int null_open(struct block_device *bdev, fmode_t mode)