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[2620:137:e000::1:20]) by mx.google.com with ESMTP id 131-20020a621689000000b00562b0b92756si8748471pfw.297.2022.11.07.06.21.10; Mon, 07 Nov 2022 06:21:24 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=pass header.i=@linutronix.de header.s=2020 header.b=Ad8er1f7; dkim=neutral (no key) header.i=@linutronix.de header.s=2020e header.b=zK+1fRr2; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=linutronix.de Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232443AbiKGOTQ (ORCPT + 99 others); Mon, 7 Nov 2022 09:19:16 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56794 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232254AbiKGOR2 (ORCPT ); Mon, 7 Nov 2022 09:17:28 -0500 Received: from galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6125F1D331 for ; Mon, 7 Nov 2022 06:16:57 -0800 (PST) From: John Ogness DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1667830616; 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=Ad8er1f7f8T+qnj0Gixt4/Eb+4c4OBJuex8lcfrI6Qt9I87cz3Yhpp3wFd3F8c5QAakGi7 n0yYpOb0XzwK6fAjOBesCSJAdkcc9KpXBouFayqOhvycH3D3yadGi/NrkdtoGLbncezA5X YjxkitS3+oQNxU51jX06dua+f/JTR0XVGlDIr8XnD/7XQCOkEkGQV7za9feSO1p2qDYB97 UumWZEnga12d8kYgQTwG2oUlZ8itzYhywnpRTKu8Ks8TF1Bk4XdZtBxWxmXB+X1cV+LfUg IEtga3BtJP43iP9Aa+RQ9n71Ed9jlHvrLDju9BL47ap7+sIADoEpSefIdM/kVg== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1667830616; 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=zK+1fRr2slLJAgCrOQ92XALV5x6DkTtyLpaf7GZ9DoHDzskWr2XYcAOYzCFmWcOd1UDl2W 031PveM/i8gqIXAg== To: Petr Mladek Cc: Sergey Senozhatsky , Steven Rostedt , Thomas Gleixner , linux-kernel@vger.kernel.org, Greg Kroah-Hartman , Jiri Slaby Subject: [PATCH printk v3 34/40] tty: tty_io: use console_list_lock for list synchronization Date: Mon, 7 Nov 2022 15:22:32 +0106 Message-Id: <20221107141638.3790965-35-john.ogness@linutronix.de> In-Reply-To: <20221107141638.3790965-1-john.ogness@linutronix.de> References: <20221107141638.3790965-1-john.ogness@linutronix.de> MIME-Version: 1.0 X-Spam-Status: No, score=-3.9 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,INVALID_DATE_TZ_ABSURD, RCVD_IN_DNSWL_MED,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1748847437815722296?= X-GMAIL-MSGID: =?utf-8?q?1748847437815722296?= 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);