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=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 EC301C49ED7 for ; Mon, 16 Sep 2019 04:30:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C8868206C2 for ; Mon, 16 Sep 2019 04:30:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727345AbfIPEa2 (ORCPT ); Mon, 16 Sep 2019 00:30:28 -0400 Received: from www262.sakura.ne.jp ([202.181.97.72]:59927 "EHLO www262.sakura.ne.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725985AbfIPEa1 (ORCPT ); Mon, 16 Sep 2019 00:30:27 -0400 Received: from fsav304.sakura.ne.jp (fsav304.sakura.ne.jp [153.120.85.135]) by www262.sakura.ne.jp (8.15.2/8.15.2) with ESMTP id x8G4UPN1082368; Mon, 16 Sep 2019 13:30:25 +0900 (JST) (envelope-from penguin-kernel@I-love.SAKURA.ne.jp) Received: from www262.sakura.ne.jp (202.181.97.72) by fsav304.sakura.ne.jp (F-Secure/fsigk_smtp/530/fsav304.sakura.ne.jp); Mon, 16 Sep 2019 13:30:25 +0900 (JST) X-Virus-Status: clean(F-Secure/fsigk_smtp/530/fsav304.sakura.ne.jp) Received: from [192.168.1.8] (softbank126227201116.bbtec.net [126.227.201.116]) (authenticated bits=0) by www262.sakura.ne.jp (8.15.2/8.15.2) with ESMTPSA id x8G4UI61082342 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NO); Mon, 16 Sep 2019 13:30:25 +0900 (JST) (envelope-from penguin-kernel@I-love.SAKURA.ne.jp) Subject: Re: printk meeting at LPC To: John Ogness Cc: Linus Torvalds , Thomas Gleixner , Steven Rostedt , Peter Zijlstra , Petr Mladek , Andrea Parri , Sergey Senozhatsky , Sergey Senozhatsky , Brendan Higgins , Greg Kroah-Hartman , LKML , "Theodore Ts'o" , Paul Turner , Daniel Vetter , Prarit Bhargava References: <20190807222634.1723-1-john.ogness@linutronix.de> <20190904123531.GA2369@hirez.programming.kicks-ass.net> <20190905130513.4fru6yvjx73pjx7p@pathway.suse.cz> <20190905143118.GP2349@hirez.programming.kicks-ass.net> <20190905121101.60c78422@oasis.local.home> <87k1acz5rx.fsf@linutronix.de> From: Tetsuo Handa Message-ID: Date: Mon, 16 Sep 2019 13:30:17 +0900 User-Agent: Mozilla/5.0 (Windows NT 6.3; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.9.0 MIME-Version: 1.0 In-Reply-To: <87k1acz5rx.fsf@linutronix.de> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2019/09/13 22:26, John Ogness wrote: > 6. A new may-sleep function pr_flush() will be made available to wait > for all previously printk'd messages to be output on all consoles before > proceeding. For example: > > pr_cont("Running test ABC... "); > pr_flush(); > > do_test(); > > pr_cont("PASSED\n"); > pr_flush(); Don't we need to allow printk() callers to know the sequence number which the printk() has queued? Something like u64 seq; pr_info(...); pr_info(...); pr_info(...); seq = pr_current_seq(); pr_wait_seq(seq); in case concurrently executed printk() flooding keeps adding a lot of pending output? By the way, do we need to keep printk() return bytes like printf() ? Maybe we can make printk() return "void", for almost nobody can do meaningful things with the return value. > 9. Support for printk dictionaries will be discontinued. I will look > into who is using this and why. If printk dictionaries are important for > you, speak up now! I think that dev_printk() is using "const char *dict, size_t dictlen," part via create_syslog_header(). Some userspace programs might depend on availability of such information.