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 C7620C433FE for ; Thu, 10 Nov 2022 13:59:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231294AbiKJN7D (ORCPT ); Thu, 10 Nov 2022 08:59:03 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40332 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230085AbiKJN7A (ORCPT ); Thu, 10 Nov 2022 08:59:00 -0500 Received: from smtp-out2.suse.de (smtp-out2.suse.de [195.135.220.29]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 853DA14099 for ; Thu, 10 Nov 2022 05:58:58 -0800 (PST) Received: from relay2.suse.de (relay2.suse.de [149.44.160.134]) by smtp-out2.suse.de (Postfix) with ESMTP id 8AF001FCD6; Thu, 10 Nov 2022 13:58:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1668088737; 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=8+BR4g4FYShDqBfZbOAElSZtj5E+C1NfPswxdJoJeCM=; b=PR2axcRFy2cLXU3lQMCGZInPKcc7R/mhN9Ym13PoeMjIPr5OrcwO0lrQ8TaFPHPUcnPpa9 UKLbf0NrHvlJLewX71/DZGRo0B9Q6UwaTActSK02Y3kDpB+bI3q5CaMj6bnRdwznIBHtSf rg6KN08uWZuU3lw6I5E7JtNbgeuPo+0= Received: from suse.cz (unknown [10.100.201.202]) (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 360112C141; Thu, 10 Nov 2022 13:58:57 +0000 (UTC) Date: Thu, 10 Nov 2022 14:58:56 +0100 From: Petr Mladek To: John Ogness Cc: Sergey Senozhatsky , Steven Rostedt , Thomas Gleixner , linux-kernel@vger.kernel.org, Geert Uytterhoeven , linux-m68k@lists.linux-m68k.org Subject: Re: [PATCH printk v3 24/40] tty: nfcon: use console_is_registered() Message-ID: References: <20221107141638.3790965-1-john.ogness@linutronix.de> <20221107141638.3790965-25-john.ogness@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20221107141638.3790965-25-john.ogness@linutronix.de> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon 2022-11-07 15:22:22, John Ogness wrote: > Currently CON_ENABLED is being (mis)used to identify if the console > has been registered. This is not reliable because it can be set even > though registration failed or it can be unset, even though the console > is registered. > > Signed-off-by: John Ogness > --- > arch/m68k/emu/nfcon.c | 10 ++++------ > 1 file changed, 4 insertions(+), 6 deletions(-) > > diff --git a/arch/m68k/emu/nfcon.c b/arch/m68k/emu/nfcon.c > index 557d60867f98..292669fa480f 100644 > --- a/arch/m68k/emu/nfcon.c > +++ b/arch/m68k/emu/nfcon.c > @@ -49,14 +49,14 @@ static void nfcon_write(struct console *con, const char *str, > static struct tty_driver *nfcon_device(struct console *con, int *index) > { > *index = 0; > - return (con->flags & CON_ENABLED) ? nfcon_tty_driver : NULL; > + return console_is_registered(con) ? nfcon_tty_driver : NULL; > } > > static struct console nf_console = { > .name = "nfcon", > .write = nfcon_write, > .device = nfcon_device, > - .flags = CON_PRINTBUFFER, > + .flags = CON_PRINTBUFFER | CON_ENABLED, This causes that register_console() will always put the console into console_list. It causes regression, see below. > .index = -1, > }; > > @@ -106,10 +106,8 @@ static int __init nf_debug_setup(char *arg) > return 0; > > stderr_id = nf_get_id("NF_STDERR"); > - if (stderr_id) { > - nf_console.flags |= CON_ENABLED; > + if (stderr_id) > register_console(&nf_console); My understanding is that this should enable the console when debug=nfcon kernel parameter is used. It is a non-standard way. This is why CON_ENABLED flag has to be explicitly set. > - } > > return 0; > } > @@ -151,7 +149,7 @@ static int __init nfcon_init(void) > > nfcon_tty_driver = driver; > > - if (!(nf_console.flags & CON_ENABLED)) > + if (!console_is_registered(&nf_console)) > register_console(&nf_console); This calls register_console() when it was not already registered by the debug=nfcon early parameter. It is the standard way. It should enable the console only when console=nfcon is defined on the commandline. Or when there is no preferred console and no console enabled by default yet. We should not pre-set CON_ENABLED in this case. Best Regards, Petr