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 B95B7C04A95 for ; Tue, 25 Oct 2022 10:15:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231224AbiJYKP5 (ORCPT ); Tue, 25 Oct 2022 06:15:57 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51128 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231220AbiJYKPi (ORCPT ); Tue, 25 Oct 2022 06:15:38 -0400 Received: from smtp-out2.suse.de (smtp-out2.suse.de [IPv6:2001:67c:2178:6::1d]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 82C1295A5; Tue, 25 Oct 2022 03:09:27 -0700 (PDT) Received: from relay2.suse.de (relay2.suse.de [149.44.160.134]) by smtp-out2.suse.de (Postfix) with ESMTP id CD37E1FD6C; Tue, 25 Oct 2022 10:09:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1666692565; 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=3ux62HDRPYlDLLBODOUnZkbRi1/eHkDR13k5JCm7MLk=; b=pe95vjayzklaVLXKUbO97EJ97WMPCsVMYOBmzxLulcVWLYFdKU6sUz2NBWSF/GJySVz+pD nlLHyQ6AjOfjpbrhd8bQedACqg6T0DS/easbo/kY8WaoRMq+AzWkdOg9Q6Tt64fZMfuFU2 yIXbNA+81edyfWKbo0+f9Lj4ttQBJN0= 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 6B0FE2C141; Tue, 25 Oct 2022 10:09:25 +0000 (UTC) Date: Tue, 25 Oct 2022 12:09:22 +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 , Greg Kroah-Hartman , Jiri Slaby , kgdb-bugreport@lists.sourceforge.net, linux-serial@vger.kernel.org Subject: Re: [PATCH printk v2 22/38] serial: kgdboc: document console_lock usage Message-ID: References: <20221019145600.1282823-1-john.ogness@linutronix.de> <20221019145600.1282823-23-john.ogness@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20221019145600.1282823-23-john.ogness@linutronix.de> Precedence: bulk List-ID: X-Mailing-List: linux-serial@vger.kernel.org On Wed 2022-10-19 17:01:44, John Ogness wrote: > kgdboc_earlycon_init() uses the console_lock to ensure that no consoles > are unregistered until the kgdboc_earlycon is setup. This is necessary > because the trapping of the exit() callback assumes that the exit() > callback is not called before the trap is setup. Great catch! Note: This behavior might be dangerous. printk_late_init() checks if the early console code is in the init section. It unregisters such consoles even when keep_bootcon parameter is used. Well, it is "not serious" and might be improved later. If the early console has this code in the early section then it is a bug and should be fixed. printk_late_init() does the best effort because this problem would block all consoles and would be hard to debug. It is the same with kgdb but it is still only a corner case and just the best effort. > Explicitly document this non-typical console_lock usage. > > Signed-off-by: John Ogness Reviewed-by: Petr Mladek Best Regards, Petr