From patchwork Mon Nov 14 16:29:28 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: John Ogness X-Patchwork-Id: 624719 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 97A9BC43219 for ; Mon, 14 Nov 2022 16:31:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237644AbiKNQbO (ORCPT ); Mon, 14 Nov 2022 11:31:14 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35896 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237708AbiKNQaw (ORCPT ); Mon, 14 Nov 2022 11:30:52 -0500 Received: from galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 46FD02F393; Mon, 14 Nov 2022 08:29:51 -0800 (PST) From: John Ogness DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1668443389; 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=4PxzIkDOo+u2ZWn4WKSm9Hq+Fp48aeu4iQFbr0MeDXE=; b=1BKrXov9UpGW8i3q7hfrAts/TS9f1RYajAbeVEXEGrtL7vaFgC21p2/gycHpZdggcRdkMR ymAXLo3nI1XznOcfkM8o5VPA4u6dK12AQ9M+D9N/Y7xJ/VWzIzjgdzIM7jZdzTrLeTEgVf ldvYptvRObxoWgQM1mjVO0U5z0p5nGCAs7EtMbBk3dTvPNu5ImyjgmMlyxInldZZtJmK2A 1C5vFloKr8VFUqWXDe8yM2OiOhAi0RIy9lNx/vMF7VcWmlEYi+lu43zGfF6mavA+0ue7WX HCOKbjnE3m0/2oipWF8vmACY9N8pHiiQtSahib4N206+Wa9R/AOzX9tdp8cgXw== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1668443389; 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=4PxzIkDOo+u2ZWn4WKSm9Hq+Fp48aeu4iQFbr0MeDXE=; b=YJxFMEQT+jRTL58bXGade43+HEy6xareEPmdNqBiX7GialR4nAAc3bII7mmuoQPHmtUymm dWTycSv7+nBOStCQ== 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 v4 35/39] tty: serial: kgdboc: use console_list_lock for list traversal Date: Mon, 14 Nov 2022 17:35:28 +0106 Message-Id: <20221114162932.141883-36-john.ogness@linutronix.de> In-Reply-To: <20221114162932.141883-1-john.ogness@linutronix.de> References: <20221114162932.141883-1-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 --- 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;