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 E0F89C4332F for ; Tue, 15 Nov 2022 15:34:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238043AbiKOPeY (ORCPT ); Tue, 15 Nov 2022 10:34:24 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35390 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232405AbiKOPeN (ORCPT ); Tue, 15 Nov 2022 10:34:13 -0500 Received: from smtp-out1.suse.de (smtp-out1.suse.de [IPv6:2001:67c:2178:6::1c]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 104E0DFEF for ; Tue, 15 Nov 2022 07:34:12 -0800 (PST) Received: from relay2.suse.de (relay2.suse.de [149.44.160.134]) by smtp-out1.suse.de (Postfix) with ESMTP id B918833688; Tue, 15 Nov 2022 15:34:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1668526450; 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=fx1pabvdNXR/4MZEXdvaDvbLnLLLuOpiVQF5f9g0kBo=; b=PRNvaJAr2b0ao2L6bSSuW4Eg76ey9yIIDFlheQf0a9IdwAjz/NHdGLvWOyV0TnRBtm8ASz hUKcCG9qws8J2HJpGP0lY+Jsn8Xq8pByubsJXX+HvcUupIkR+I+huCwHl8KFvfT4faSJ1w gdOJ0YqwXl2/NEzOgP0bhBCjG6teMO4= 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 8CE642C142; Tue, 15 Nov 2022 15:34:10 +0000 (UTC) Date: Tue, 15 Nov 2022 16:34:10 +0100 From: Petr Mladek To: John Ogness Cc: Sergey Senozhatsky , Steven Rostedt , Thomas Gleixner , linux-kernel@vger.kernel.org Subject: replay log: Re: [PATCH printk v4 38/39] printk: relieve console_lock of list synchronization duties Message-ID: References: <20221114162932.141883-1-john.ogness@linutronix.de> <20221114162932.141883-39-john.ogness@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20221114162932.141883-39-john.ogness@linutronix.de> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon 2022-11-14 17:35:31, John Ogness wrote: > The console_list_lock provides synchronization for console list and > console->flags updates. All call sites that were using the console_lock > for this synchronization have either switched to use the > console_list_lock or the SRCU list iterator. > > Remove console_lock usage for console list updates and console->flags > updates. > > Signed-off-by: John Ogness > --- a/kernel/printk/printk.c > +++ b/kernel/printk/printk.c > @@ -3334,6 +3330,11 @@ void register_console(struct console *newcon) > * boot console that is the furthest behind. > */ > if (bootcon_registered && !keep_bootcon) { > + /* > + * Hold the console_lock to guarantee safe access to > + * console->seq. > + */ > + console_lock(); > for_each_console(con) { > if ((con->flags & CON_BOOT) && > (con->flags & CON_ENABLED) && > @@ -3341,6 +3342,7 @@ void register_console(struct console *newcon) > newcon->seq = con->seq; > } > } > + console_unlock(); Thinking more about it. This console_unlock() will actually cause flushing the boot consoles. A solution would be to call console_flush_all() here. And we could/should solve this in a separate patch. This code was not locked before. It is a corner case. It could be solved later. > } > } > Best Regards, Petr