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 BBACAC4332F for ; Tue, 15 Nov 2022 12:27:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229735AbiKOM1F (ORCPT ); Tue, 15 Nov 2022 07:27:05 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47944 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229490AbiKOM1D (ORCPT ); Tue, 15 Nov 2022 07:27:03 -0500 Received: from smtp-out2.suse.de (smtp-out2.suse.de [IPv6:2001:67c:2178:6::1d]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id EB740247 for ; Tue, 15 Nov 2022 04:27:01 -0800 (PST) Received: from relay2.suse.de (relay2.suse.de [149.44.160.134]) by smtp-out2.suse.de (Postfix) with ESMTP id 521551F8BB; Tue, 15 Nov 2022 12:27:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1668515220; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=o1GPphquw5VzfuGry5gzn0ZGXLKC+qRxtGb2SeLfGOY=; b=ZN4/m77PRVAF67ayyAoMT1+TfvptHhOYs8LeSzEYinv9muvna+10t1nkIWeDPghps4bQF4 Qsg7V1ClaDycKzOoi6ebx5YvnQ9xHHb3JyER4JnADXJd7nllOmDPpciA7nWC/AriNtGS0u aEi3IkQlX9eTLKWsHaElemsrHpZrsgs= Received: from suse.cz (unknown [10.100.208.146]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by relay2.suse.de (Postfix) with ESMTPS id 047992C142; Tue, 15 Nov 2022 12:26:59 +0000 (UTC) Date: Tue, 15 Nov 2022 13:26:59 +0100 From: Petr Mladek To: John Ogness Cc: Sergey Senozhatsky , Steven Rostedt , Thomas Gleixner , linux-kernel@vger.kernel.org, Greg Kroah-Hartman Subject: Re: [PATCH printk v4 11/39] console: introduce wrappers to read/write console flags Message-ID: References: <20221114162932.141883-1-john.ogness@linutronix.de> <20221114162932.141883-12-john.ogness@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20221114162932.141883-12-john.ogness@linutronix.de> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon 2022-11-14 17:35:04, John Ogness wrote: > After switching to SRCU for console list iteration, some readers > will begin readings console->flags as a data race. Locklessly > reading console->flags provides a consistent value because there > is at most one CPU modifying console->flags and that CPU is > using only read-modify-write operations. > > Introduce a wrapper for SRCU iterators to read console flags. > Introduce a matching wrapper to write to flags of registered > consoles. Writing to flags of registered consoles is synchronized > by the console_list_lock. > > Signed-off-by: John Ogness Reviewed-by: Petr Mladek Best Regards, Petr