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 967A5C43217 for ; Wed, 16 Nov 2022 16:25:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238660AbiKPQZo (ORCPT ); Wed, 16 Nov 2022 11:25:44 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58688 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237884AbiKPQWy (ORCPT ); Wed, 16 Nov 2022 11:22:54 -0500 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8293758BD5 for ; Wed, 16 Nov 2022 08:22:14 -0800 (PST) From: John Ogness DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1668615733; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=OuuuTA4YWeOsJFG5PLdantkjarf2V1vxrJ2SuyPt64s=; b=GqEDEE3zp/IRKIG7fVAtRnGyQYw8WjwWd4Q42w/o6PvPKiYO/I2UO9DeTHM3FJ0AKO0jvp LdOOd6uoG+vhbGCFBO7LBcXhhdAUApmgiQs0vuidLt14ucgw4AvLmW3ELjtEKxLG3N4KGx Q+9wx4UCYMejQEuvs0LMZiYK45HlAH2uV2vbxLpNjLMnhI4VYzHLHvp7JVcTvWg9ZPaU4Y qBnwFK9fzDv3qO7YojD6nmxsxJ6UqqxLGW+8ec2hNQOjRHVhBBr3T21cpJRNKBLJGbDGij w/e68WEuDCriejd7+eCTKF+cvy9G5bS5T0Z2sVAKmxN7wYRNwAe3135cVf0Dhg== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1668615733; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=OuuuTA4YWeOsJFG5PLdantkjarf2V1vxrJ2SuyPt64s=; b=cWNjqkiifbJnp+I8ut0vwNHx0n+1msAV6ALZLKMXEExGS/PVCCHSzpewmPRNwZytzWeWNm pETM9jyn9FGbzaBA== To: Petr Mladek Cc: Sergey Senozhatsky , Steven Rostedt , Thomas Gleixner , linux-kernel@vger.kernel.org, Greg Kroah-Hartman , Jiri Slaby Subject: [PATCH printk v5 33/40] tty: tty_io: use console_list_lock for list synchronization Date: Wed, 16 Nov 2022 17:27:45 +0106 Message-Id: <20221116162152.193147-34-john.ogness@linutronix.de> In-Reply-To: <20221116162152.193147-1-john.ogness@linutronix.de> References: <20221116162152.193147-1-john.ogness@linutronix.de> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org show_cons_active() uses the console_lock to gather information on registered consoles. It requires that no consoles are unregistered until it is finished. The console_list_lock should be used because list synchronization responsibility will be removed from the console_lock in a later change. Note, the console_lock is still needed to serialize the device() callback with other console operations. Signed-off-by: John Ogness Reviewed-by: Greg Kroah-Hartman Reviewed-by: Petr Mladek --- drivers/tty/tty_io.c | 18 ++++++++++++------ 1 file changed, 12 insertions(+), 6 deletions(-) diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c index ee4da2fec328..cafdff575716 100644 --- a/drivers/tty/tty_io.c +++ b/drivers/tty/tty_io.c @@ -3527,16 +3527,13 @@ static ssize_t show_cons_active(struct device *dev, ssize_t count = 0; /* - * Hold the console_lock to guarantee that no consoles are + * Hold the console_list_lock to guarantee that no consoles are * unregistered until all console processing is complete. * This also allows safe traversal of the console list and * race-free reading of @flags. - * - * Take console_lock to serialize device() callback with - * other console operations. For example, fg_console is - * modified under console_lock when switching vt. */ - console_lock(); + console_list_lock(); + for_each_console(c) { if (!c->device) continue; @@ -3548,6 +3545,13 @@ static ssize_t show_cons_active(struct device *dev, if (i >= ARRAY_SIZE(cs)) break; } + + /* + * Take console_lock to serialize device() callback with + * other console operations. For example, fg_console is + * modified under console_lock when switching vt. + */ + console_lock(); while (i--) { int index = cs[i]->index; struct tty_driver *drv = cs[i]->device(cs[i], &index); @@ -3563,6 +3567,8 @@ static ssize_t show_cons_active(struct device *dev, } console_unlock(); + console_list_unlock(); + return count; } static DEVICE_ATTR(active, S_IRUGO, show_cons_active, NULL); -- 2.30.2