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 X-Spam-Level: X-Spam-Status: No, score=-9.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E2828C4338F for ; Tue, 27 Jul 2021 08:00:02 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id A83C1611ED for ; Tue, 27 Jul 2021 08:00:02 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org A83C1611ED Authentication-Results: mail.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=RIPMBU8KkQ869rKTIm6K9aPp7lpH6awf/1JD5/3XwtM=; b=yBwJB0iw//PHd7 ceRyQzYYOMNotC6gh9iScG4qJ75gATZtjWxjQzzESSMxOJyrl2YMV5+YyVSkd1xitXHX790bfjmZP QWgmbSpWRCqAr0K1Vm4E1nvNB0pjueEJBCGeQAbOseee6+FUq5HpBV6c3r0yxXv6sqt2Ynaky4Mqa XO/wYgHi/meqG6CV1lgyaHziK1MxIzYt9PaGK3Zn1M1uXSEOpPbkShKNb3PlyvpqMJiCVKdYBR6ZB mwQNZzaeb8uFlug6ivwISpD/J4I80yu/n9uw1pLuhYXaPlxRwZUem1nswDDZensKZmZtqDhUBs+Oj MKvkomvIwTUluctK7f3Q==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1m8Hy1-00Dwjq-PI; Tue, 27 Jul 2021 07:57:35 +0000 Received: from smtp-out1.suse.de ([195.135.220.28]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1m8HUS-00DpL5-PI; Tue, 27 Jul 2021 07:27:03 +0000 Received: from relay2.suse.de (relay2.suse.de [149.44.160.134]) by smtp-out1.suse.de (Postfix) with ESMTP id 145C322103; Tue, 27 Jul 2021 07:26:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1627370816; 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=BIRDRD9L4czToF86gzK0EPiIaFDmmYi9JHkmXI3ngzQ=; b=nJqvAQvqUxZZ5iCL8QYWjWGPVyDkMYBjRJVMYG19s7WhBLGIG4Kg9PRrCjcMUHPW5yFHCM 2mF/l/4bgDhpI+TWQPFm3lrdvLLUZBwX8OZdqxGQ4wX+eJqBw55B2LjMIA1DCAGo4Lvkm4 +SJtF34yqgIyDeVCvZyZaFocQovqWtE= Received: from suse.cz (unknown [10.100.224.162]) (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 8A49BA3B81; Tue, 27 Jul 2021 07:26:54 +0000 (UTC) Date: Tue, 27 Jul 2021 09:26:54 +0200 From: Petr Mladek To: John Ogness Cc: Sergey Senozhatsky , Steven Rostedt , Thomas Gleixner , linux-kernel@vger.kernel.org, "Paul E. McKenney" , Michael Ellerman , Benjamin Herrenschmidt , Paul Mackerras , Eric Biederman , Nicholas Piggin , Christophe Leroy , =?iso-8859-1?Q?C=E9dric?= Le Goater , Andrew Morton , Kees Cook , Tiezhu Yang , Alexey Kardashevskiy , Yue Hu , linuxppc-dev@lists.ozlabs.org, kexec@lists.infradead.org, Russell King , Ingo Molnar , Marc Zyngier , Valentin Schneider , Geert Uytterhoeven , Mike Rapoport , "Wolfram Sang (Renesas)" , Anshuman Khandual , Xiongwei Song , Frederic Weisbecker , Peter Zijlstra , Masahiro Yamada , Nathan Chancellor , Nick Desaulniers , Nick Terrell , Vipin Sharma , Rasmus Villemoes , Daniel Borkmann , Vlastimil Babka , linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH printk v4 0/6] printk: remove safe buffers Message-ID: References: <20210715193359.25946-1-john.ogness@linutronix.de> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20210715193359.25946-1-john.ogness@linutronix.de> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210727_002701_027421_DACDEB1F X-CRM114-Status: GOOD ( 23.90 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Thu 2021-07-15 21:39:53, John Ogness wrote: > Hi, > > Here is v4 of a series to remove the safe buffers. v3 can be > found here [0]. The safe buffers are no longer needed because > messages can be stored directly into the log buffer from any > context. > > However, the safe buffers also provided a form of recursion > protection. For that reason, explicit recursion protection is > implemented for this series. > > The safe buffers also implicitly provided serialization > between multiple CPUs executing in NMI context. This was > particularly necessary for the nmi_backtrace() output. This > serializiation is now preserved by using the printk cpulock. > > With the removal of the safe buffers, there is no need for > extra NMI enter/exit tracking. So this is also removed > (which includes removing the config option CONFIG_PRINTK_NMI). > > And finally, there are a few places in the kernel that need to > specify code blocks where all printk calls are to be deferred > printing. Previously the NMI tracking API was being (mis)used > for this purpose. This series introduces an official and > explicit interface for such cases. (Note that all deferred > printing will be removed anyway, once printing kthreads are > introduced.) > > John Ogness (6): > lib/nmi_backtrace: explicitly serialize banner and regs > printk: track/limit recursion > printk: remove safe buffers > printk: remove NMI tracking > printk: convert @syslog_lock to mutex > printk: syslog: close window between wait and read The entire patchset has been committed into printk/linux.git, branch rework/printk_safe-removal. Note that I have updated the 4th patch as discussed, see https://lore.kernel.org/r/20210721120026.y3dqno24ahw4sazy@pathway.suse.cz https://lore.kernel.org/r/20210721130852.zrjnti6b3fwjgdzj@pathway.suse.cz Best Regards, Petr _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel