From nobody Tue Apr 7 22:02:49 2026 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 3E586C433FE for ; Wed, 16 Nov 2022 16:22:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236345AbiKPQWt (ORCPT ); Wed, 16 Nov 2022 11:22:49 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58670 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233587AbiKPQWE (ORCPT ); Wed, 16 Nov 2022 11:22:04 -0500 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BE17D49B68; Wed, 16 Nov 2022 08:22:03 -0800 (PST) From: John Ogness DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1668615722; 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=WyGtVM99u5kVDH70iZExE1J1KzxzFf6H5/dTCHJGWmg=; b=OkggJBlHCa9L4cp9ZDwwAsfL5ubRsoOncME3GDT90isJ+qp7J73h9NygngEEZiEoWr+es/ 3Upl4H1KrQnB9vC4v5gJ8xNfgM03fTyq0Hvw3HyW+NTRBO9RDXHTzuY5yyRaWNip4KoUlo jv8o3KtDRDJ5vnJjCybJF2iNMAlOfQr0Z0EssP9z6UoZbQUp+vf741jMgzncq8Q944gZyU q/EDZaCvZe+84tYeDpcZt+1MrsFtlBB5PuIi0o6f70Fv1eF0z3tUS8sMp3rL7kwVtceE+v QzzsEhnN/iuaaeQLCD0aYQE0OgwigXV3QCHRchsu1ujqaQU2+c+KX3u9rJFQzQ== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1668615722; 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=WyGtVM99u5kVDH70iZExE1J1KzxzFf6H5/dTCHJGWmg=; b=05p9Fgr9oIC1rseJZa7drAisqg0/FWrb79iEbbJ3VXznN77H03kThzDxWjsXNFc/82FzCY mJAwymv7Gr0kdEBw== To: Petr Mladek Cc: Sergey Senozhatsky , Steven Rostedt , Thomas Gleixner , linux-kernel@vger.kernel.org, Greg Kroah-Hartman , linux-fsdevel@vger.kernel.org Subject: [PATCH printk v5 10/40] proc: consoles: document console_lock usage Date: Wed, 16 Nov 2022 17:27:22 +0106 Message-Id: <20221116162152.193147-11-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: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" The console_lock is held throughout the start/show/stop procedure to print out device/driver information about all registered consoles. Since the console_lock is being used for multiple reasons, explicitly document these reasons. This will be useful when the console_lock is split into fine-grained locking. Signed-off-by: John Ogness Reviewed-by: Petr Mladek --- fs/proc/consoles.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/fs/proc/consoles.c b/fs/proc/consoles.c index cf2e0788f9c7..46b305fa04ed 100644 --- a/fs/proc/consoles.c +++ b/fs/proc/consoles.c @@ -63,6 +63,15 @@ static void *c_start(struct seq_file *m, loff_t *pos) struct console *con; loff_t off =3D 0; =20 + /* + * Take console_lock to serialize device() callback with + * other console operations. For example, fg_console is + * modified under console_lock when switching vt. + * + * Hold the console_lock to guarantee safe traversal of the + * console list. SRCU cannot be used because there is no + * place to store the SRCU cookie. + */ console_lock(); for_each_console(con) if (off++ =3D=3D *pos) --=20 2.30.2