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=-10.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 7652DC49361 for ; Thu, 17 Jun 2021 11:23:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4AE88613D5 for ; Thu, 17 Jun 2021 11:23:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232548AbhFQLZa (ORCPT ); Thu, 17 Jun 2021 07:25:30 -0400 Received: from smtp-out2.suse.de ([195.135.220.29]:34180 "EHLO smtp-out2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232094AbhFQLZ3 (ORCPT ); Thu, 17 Jun 2021 07:25:29 -0400 Received: from relay2.suse.de (relay2.suse.de [149.44.160.134]) by smtp-out2.suse.de (Postfix) with ESMTP id 5D47E1FDD5; Thu, 17 Jun 2021 11:23:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1623929001; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=HX1faego5vfkn9CY9e5adLzo+Nz153gQ8o/qvgIZ4QI=; b=nRRU/oL51WtuiFHZRbFzQEfpDS5qHd56zU5QuZ24VdJteb+n8GqUv4ho7kVJHE75HCcauz LB6ewQkBxZt9mcFxyHV8KFIFNGriE1rqiGPMHvrwBRxx18CPe6ZT+5JJzNNpaJ4sU3s5u6 Ky6Q3FIVHFyehA3xMHvgkc4JwzH+fKY= Received: from suse.cz (unknown [10.100.224.162]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by relay2.suse.de (Postfix) with ESMTPS id D514BA3BB8; Thu, 17 Jun 2021 11:23:20 +0000 (UTC) Date: Thu, 17 Jun 2021 13:23:20 +0200 From: Petr Mladek To: John Ogness Cc: Sergey Senozhatsky , Steven Rostedt , Thomas Gleixner , linux-kernel@vger.kernel.org, Stephen Rothwell , Andrew Morton , Peter Zijlstra , Daniel Bristot de Oliveira , Stephen Boyd , Alexander Potapenko , "Paul E. McKenney" Subject: Re: [PATCH next v4 0/2] introduce printk cpu lock Message-ID: References: <20210617095051.4808-1-john.ogness@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210617095051.4808-1-john.ogness@linutronix.de> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu 2021-06-17 11:56:49, John Ogness wrote: > Hello, > > While working on removing the safe buffers for printk [0] we > stumbled on a cpu-reentrant spinning lock used by dump_stack(). This > type of lock (dubbed a cpu lock) will cause deadlock risks once we > introduce atomic consoles because atomic consoles also need such a > lock. > > Although we are not yet ready to introduce atomic consoles, this is > an appropriate time to provide an official cpu lock to be used for > all things relating to printk (including the atomic consoles, once > they are introduced). > > An example of cpu lock usage for atomic consoles can be found in the > PREEMPT_RT tree, such as the serial8250 implementation [1] of an > atomic console. (In PREEMPT_RT the printk cpu lock function was > named console_atomic_lock/_unlock.) > > This series is against next-20210616. > > John Ogness (2): > lib/dump_stack: move cpu lock to printk.c > printk: fix cpu lock ordering For both patches: Reviewed-by: Petr Mladek The patchset is ready for linux-next from my POV. We are getting close to the merge window so I am going to push it tomorrow. We could always remove it when anyone has comments the following week. Best Regards, Petr