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=-2.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT 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 730B0C282C4 for ; Wed, 13 Feb 2019 01:41:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3EB17222BB for ; Wed, 13 Feb 2019 01:41:49 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="mR4wYxzv" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1733148AbfBMBlr (ORCPT ); Tue, 12 Feb 2019 20:41:47 -0500 Received: from mail-pg1-f194.google.com ([209.85.215.194]:40457 "EHLO mail-pg1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727458AbfBMBlq (ORCPT ); Tue, 12 Feb 2019 20:41:46 -0500 Received: by mail-pg1-f194.google.com with SMTP id z10so349931pgp.7; Tue, 12 Feb 2019 17:41:46 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=NzkwmkVz5oU1xpV7JOcXij1a00PAyQd+cP0wD+5zUwE=; b=mR4wYxzvi6TXLJZoW3LOKHW/QcYo44Hm2eNhKOOe+YtLrE/sm4bOBwrHz6gUG3JSXZ V8N/OS0al1NqcvmCwv4Y08O1QFdNaZ23J23WJ7c/AkvrVz3UqAdC2Ph9fTwQ3QRE/wlG BSBzoASaE4xQSiF/wefdu+Gm7EA5EjLXFrDfIVESF9aUYfqeAOpJkbG3gptNcrrtLb0T Pi+HG3XigVkPCAEmv7TBHnpZ10TZ24bOiV41euK0dz79ZdWg3JucN3xM3e0v7si/ns57 ZD6dht2Zcgp9gFib4fHgVVKynzPmpmFkcWvVx45rIMFKUrUeByDnyg3k3eQuitQbH/2k d7nA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=NzkwmkVz5oU1xpV7JOcXij1a00PAyQd+cP0wD+5zUwE=; b=mdk3PTYqOtUFbJ98CPYDar64KUZUXq/ESLhbCLrDvNPplezNevHBgpHW1ACu7T+3CI dOE1UJbJNT+mcMdRnHDm4UqVr6i/djwpH5t7GVVq7EJsWoc6shFFYiSHrcadvCQ2pHER FUrm/0mxueoJ0Ew5Ep3ByDQb9RTXY9n9FySuhd876bUq0vyfH2OJz83AEq1YZMY1eaGV aCFMl8h1WY+3ieAQ9+kr8m1u8JRoVr2VuTo9SEMgDgJ3g6S1TpcvzW5gdrHwSGQXmVdt WU7M5wdgdTYfetqJa+EwJJRDeg5WuKoY0g7PFEZL+nIURpB8KjYCK170WfCjlf8fbZOJ j8Rg== X-Gm-Message-State: AHQUAuZ6kJ69c4AKIDbzcMQno7uQA0p1o9pOApTfNmt9Ea3BbOZGqbWp 4nng+me5l2r5L/SkdcyAgmfm+F7r X-Google-Smtp-Source: AHgI3IadHoKc21ku89jVRcGqyGthWV6DWjzP62YNe6ghJ0l661WkmM+YV05/1eoiLVbPXUuhS2wL5A== X-Received: by 2002:a62:53c5:: with SMTP id h188mr6841531pfb.190.1550022105970; Tue, 12 Feb 2019 17:41:45 -0800 (PST) Received: from localhost ([39.7.15.189]) by smtp.gmail.com with ESMTPSA id f12sm17676392pgo.13.2019.02.12.17.41.44 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Tue, 12 Feb 2019 17:41:45 -0800 (PST) Date: Wed, 13 Feb 2019 10:41:41 +0900 From: Sergey Senozhatsky To: John Ogness Cc: linux-kernel@vger.kernel.org, Peter Zijlstra , Petr Mladek , Sergey Senozhatsky , Steven Rostedt , Daniel Wang , Andrew Morton , Linus Torvalds , Greg Kroah-Hartman , Alan Cox , Jiri Slaby , Peter Feiner , linux-serial@vger.kernel.org, Sergey Senozhatsky Subject: Re: [RFC PATCH v1 00/25] printk: new implementation Message-ID: <20190213014141.GB8097@jagdpanzerIV> References: <20190212143003.48446-1-john.ogness@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190212143003.48446-1-john.ogness@linutronix.de> User-Agent: Mutt/1.11.3 (2019-02-01) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On (02/12/19 15:29), John Ogness wrote: > - console_flush_on_panic() currently is a NOP. It is pretty clear how > this could be implemented if atomic_write was available. But if no > such console is registered, it is not clear what should be done. Is > this function really even needed? If you now rely on a fully preemptible printk kthread to flush pending logbuf messages, then console_flush_on_panic() is your only chance to see those pending logbuf messages on the serial console when the system dies. Non-atomic consoles should become atomic once you call bust_spinlocks(1), this is what we currently have: panic() bust_spinlocks(1) // sets oops_in_progress console_flush_on_panic() call_console_drivers() -> serial_driver_write() if (oops_in_progress) locked = spin_trylock_irqsave(&port->lock); uart_console_write(); if (locked) spin_unlock_irqrestore(&port->lock); -ss