From patchwork Wed Nov 16 16:21:48 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: John Ogness X-Patchwork-Id: 626029 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 5F7B8C4332F for ; Wed, 16 Nov 2022 16:25:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238427AbiKPQZL (ORCPT ); Wed, 16 Nov 2022 11:25:11 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:32804 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238422AbiKPQXK (ORCPT ); Wed, 16 Nov 2022 11:23:10 -0500 Received: from galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 415C458BF2; Wed, 16 Nov 2022 08:22:17 -0800 (PST) From: John Ogness DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1668615735; 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=8rR7OgmI/JUsM6cOvDEez6+6LhtAAivMeCFIKDYeiDs=; b=yek+I+AWhez5rkEA5jpNLeS+dTK2vOYMuw49/4KeOx+vZ3j7fSICGh+A7GDKzg5z7TNe2w GNw3aJ8GgsUetQiTtAe6edQKm2iFjgqj4sP/xbEFwx5FjRjF+o3qdfUN8VptbvgQ1FTgSU XNuT7pmvKcUE6jWrDCsA8If0jfaxz/Nfe59VftfvTuxUeW3lurw11BtZ43HdyVaJd/ROh6 AXV7vSqILME+Fby/jKq7IUA2zE+x+sKNyx1ZxF8IafSf1P7CUoGoNq4M6G9DeWlhcmumgB 9rzjBdRedJFUuh6GLZNJHCwNg1g0XRq+YBkVa1FS/uzQFrOkhHTRPBf3H3u0jQ== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1668615735; 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=8rR7OgmI/JUsM6cOvDEez6+6LhtAAivMeCFIKDYeiDs=; b=BUIX13s3OtJiinZiPhHeHtVgfLl3mq3vyjm9l09/OnWGIn8MwDBkNG+hBGTwiLBOEgYOs4 z5ZfPI5vGKcwmmCA== To: Petr Mladek 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: [PATCH printk v5 36/40] tty: serial: kgdboc: use console_list_lock for list traversal Date: Wed, 16 Nov 2022 17:27:48 +0106 Message-Id: <20221116162152.193147-37-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 Precedence: bulk List-ID: X-Mailing-List: linux-serial@vger.kernel.org configure_kgdboc() uses the console_lock for console list iteration. Use the console_list_lock instead because list synchronization responsibility will be removed from the console_lock in a later change. The SRCU iterator could have been used here, but a later change will relocate the locking of the console_list_lock to also provide synchronization against register_console(). Note, the console_lock is still needed to serialize the device() callback with other console operations. Signed-off-by: John Ogness Reviewed-by: Petr Mladek --- drivers/tty/serial/kgdboc.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/drivers/tty/serial/kgdboc.c b/drivers/tty/serial/kgdboc.c index c6df9ef34099..82b4b4d67823 100644 --- a/drivers/tty/serial/kgdboc.c +++ b/drivers/tty/serial/kgdboc.c @@ -193,7 +193,16 @@ static int configure_kgdboc(void) if (!p) goto noconfig; + /* For safe traversal of the console list. */ + console_list_lock(); + + /* + * 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(); + for_each_console(cons) { int idx; if (cons->device && cons->device(cons, &idx) == p && @@ -202,8 +211,11 @@ static int configure_kgdboc(void) break; } } + console_unlock(); + console_list_unlock(); + kgdb_tty_driver = p; kgdb_tty_line = tty_line;