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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5B9F9C74A5B for ; Wed, 29 Mar 2023 08:03:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229798AbjC2IDp (ORCPT ); Wed, 29 Mar 2023 04:03:45 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57518 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229615AbjC2IDl (ORCPT ); Wed, 29 Mar 2023 04:03:41 -0400 Received: from smtp-out1.suse.de (smtp-out1.suse.de [195.135.220.28]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C605A3AB8; Wed, 29 Mar 2023 01:03:39 -0700 (PDT) Received: from relay2.suse.de (relay2.suse.de [149.44.160.134]) by smtp-out1.suse.de (Postfix) with ESMTP id 7F852219E7; Wed, 29 Mar 2023 08:03:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1680077018; 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=ICn2IUeBEefhWUnrVwwgjW98U4BhJgsWujMRsb5uiew=; b=FJS+18HMODTwNmHvvxxOJaelViHM+6afdk9Pgzu6vt4DkahdE6qeAZmAS2mImejCjWuCod pTjIstQ62m9cov9oi8oweZjZvdtEDYtmSxnvHBCOYsAua1FNyY8AJlOgQhvCm5e1mw8hV9 oNbWsqoqiejrQuKT5r84TeQdZ9c2enk= Received: from suse.cz (unknown [10.100.208.146]) (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 E98FB2C141; Wed, 29 Mar 2023 08:03:36 +0000 (UTC) Date: Wed, 29 Mar 2023 10:03:34 +0200 From: Petr Mladek To: John Ogness Cc: Sergey Senozhatsky , Steven Rostedt , Thomas Gleixner , linux-kernel@vger.kernel.org, Jason Wessel , Daniel Thompson , Douglas Anderson , Aaron Tomlin , Luis Chamberlain , kgdb-bugreport@lists.sourceforge.net, Greg Kroah-Hartman , linux-fsdevel@vger.kernel.org, Andrew Morton , "Guilherme G. Piccoli" , David Gow , Tiezhu Yang , Daniel Vetter , tangmeng , "Paul E. McKenney" , Frederic Weisbecker , Neeraj Upadhyay , Josh Triplett , Mathieu Desnoyers , Lai Jiangshan , Joel Fernandes , rcu@vger.kernel.org Subject: Re: locking API: was: [PATCH printk v1 00/18] serial: 8250: implement non-BKL console Message-ID: References: <20230302195618.156940-1-john.ogness@linutronix.de> <87wn3zsz5x.fsf@jogness.linutronix.de> <87a5zxger3.fsf@jogness.linutronix.de> <87ilekmtuj.fsf@jogness.linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87ilekmtuj.fsf@jogness.linutronix.de> Precedence: bulk List-ID: X-Mailing-List: rcu@vger.kernel.org On Tue 2023-03-28 23:53:16, John Ogness wrote: > On 2023-03-28, Petr Mladek wrote: > >> If an atomic context loses ownership while doing certain activities, > >> it may need to re-acquire ownership in order to finish or cleanup > >> what it started. > > > > This sounds suspicious. If a console/writer context has lost the lock > > then all shared/locked resources might already be used by the new > > owner. > > Correct. > > > I would expect that the context could touch only non-shared resources > > after loosing the lock. > > Correct. > > The 8250 driver must disable interrupts before writing to the TX > FIFO. After writing it re-enables the interrupts. However, it might be > the case that the interrupts were already disabled, in which case after > writing they are left disabled. I see. The reacquire() makes sense now. Thanks a lot for explanation. Best Regards, Petr