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=-2.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no 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 78F10C433FE for ; Tue, 8 Dec 2020 20:52:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 46E3122582 for ; Tue, 8 Dec 2020 20:52:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728833AbgLHUw1 (ORCPT ); Tue, 8 Dec 2020 15:52:27 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42814 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727193AbgLHUw1 (ORCPT ); Tue, 8 Dec 2020 15:52:27 -0500 Received: from mail-pl1-x631.google.com (mail-pl1-x631.google.com [IPv6:2607:f8b0:4864:20::631]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3645DC0613CF for ; Tue, 8 Dec 2020 12:51:41 -0800 (PST) Received: by mail-pl1-x631.google.com with SMTP id u4so1929590plr.12 for ; Tue, 08 Dec 2020 12:51:41 -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; bh=IDh1X7OB7wW8jbY8KXws0mweSxrU0MD7uaeCBRTpxI4=; b=BuT/VqEtkyxPV+Bb5g5ZS76YF4g46mfxn22JjYtqxYsYpZIXcEHaWhHkmAUTOC82dD o5ZhFxiZFBwLdR15mLm5sTKV7SOrIt5e3E5et/a7SOmzSELTcgDQIDM3GaiNoR6lCNIg taOzVyA+1S6l8GlBh1NuxgNy+El2nUSpz+rYn9yiUBd5Td9CLiGZbdE4iUhyRzZ6YVN9 +uhFmx6stxm4DyTJrj94Vrk27rHtkgMmBv30zKL1mFXQeoxeGQRveDxj1XpP00sQo4Oe 1CBLgQ2Kd19sYpqSJxtfeb1lNJtz/rwHaoscoiW4wIERtUvtBO+YR2/aBlw+ImuQDEOC h8Dg== 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; bh=IDh1X7OB7wW8jbY8KXws0mweSxrU0MD7uaeCBRTpxI4=; b=jeph9hi5ZBRlsuS1mNzY5FqH2tZcH3qc7P/X97eI1zSjh0FNOWD6WLdFaXpYLN0RSc HfLfMmHXgb+qBbsIf2v/lp59TTgGsvSNMba7hOnUlhjgOJSgF1b79OorUZWaDi+FfFYZ L2LH1EG7DTFiDtWSZxtnKYcqWlF9zvIxTNowTIz2a3g3LFlYDvlIN7z+pDlSexnFq9c+ yLND6TkvyiMX6+wJX/eM44aF362RdgusFhSy04T4rqN8lbfHeLBmnTBWM8rb+UzwSwRj 8VEPot/IkDWshrZAMQka9h8q/k5UZSYeMd5Aubv5iX5yH0UZSK4Hzj6bMLxGj0L+DNQ6 C1KQ== X-Gm-Message-State: AOAM530tZHClr86H+fgW70VvRT4VreKfS36AAXhkcLFXoCcOuomiLW8/ jkYzoAdG7W+CDK/eQ6UK4o8= X-Google-Smtp-Source: ABdhPJwYfGUca0k7wAXMk4KHtDu1qAKlqwa/YKCCkTjvnk0A7b7tq7c0sV7T/nj4ZX8+QId9aZFS/g== X-Received: by 2002:a17:902:aa8b:b029:da:ef22:8675 with SMTP id d11-20020a170902aa8bb02900daef228675mr1319869plr.15.1607460700672; Tue, 08 Dec 2020 12:51:40 -0800 (PST) Received: from localhost ([2409:10:2e40:5100:6e29:95ff:fe2d:8f34]) by smtp.gmail.com with ESMTPSA id x10sm26156pff.214.2020.12.08.12.51.39 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 08 Dec 2020 12:51:39 -0800 (PST) Date: Wed, 9 Dec 2020 05:51:37 +0900 From: Sergey Senozhatsky To: Petr Mladek Cc: Sergey Senozhatsky , John Ogness , Sergey Senozhatsky , Steven Rostedt , Linus Torvalds , Greg Kroah-Hartman , Thomas Gleixner , linux-kernel@vger.kernel.org Subject: Re: consoles: was: [PATCH next v2 3/3] printk: remove logbuf_lock, add syslog_lock Message-ID: References: <20201201205341.3871-1-john.ogness@linutronix.de> <20201201205341.3871-4-john.ogness@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On (20/12/07 10:50), Petr Mladek wrote: [..] > > and then some call into the scheduler > > (or other kernel core functions) under semaphore's spin_lock. > > For instance > > > > up() > > raw_spin_lock_irqsave(&sem->lock) > > __up() > > wake_up_process() > > try_to_wake_up() > > This problem is partly solved by printk_deferred(). In each > case, printk_safe() does not help here. printk_deferred() has never been used in all the critical code paths. So I think printk_safe does help here; it takes care of all the remaining cases, that are not "partly solved by printk_deferred()". > I still do _not_ see a reason to keep printk_safe()! Not sure I'm following, sorry. To put it simply - we better keep printk_safe until "new recursion prevention" >= printk_safe(). In this patch set "new recursion prevention" < printk_safe(). -ss