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 642DFC4361A for ; Sat, 5 Dec 2020 09:45:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1E77622DFA for ; Sat, 5 Dec 2020 09:45:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726744AbgLEJpO (ORCPT ); Sat, 5 Dec 2020 04:45:14 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45064 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725924AbgLEJmq (ORCPT ); Sat, 5 Dec 2020 04:42:46 -0500 Received: from mail-pl1-x644.google.com (mail-pl1-x644.google.com [IPv6:2607:f8b0:4864:20::644]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 83A8BC061A4F for ; Sat, 5 Dec 2020 01:41:08 -0800 (PST) Received: by mail-pl1-x644.google.com with SMTP id f1so4490399plt.12 for ; Sat, 05 Dec 2020 01:41:08 -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=YDD8AKO2hwLZeCjZwKKM5uCY10n51t2OVbGyoK51PNI=; b=fORnjR2PEjZ039a/Ekr6vs9LZSRTtrsKtY6rEDeZngNqgCeEValdj/QgzknyQw6/iX OT9LdPwbJ/bf5+TNagASIlfq2EtWMvBmQ/4FNtmEJZjpksnuRpslO1TLMWodtSQhcWoA 4l2FLvlSI8c3wtsnplpJ/aNtutpJuPKuJ2U2CqW6M961XA9l+axmq9d/jfLqP+aAAiST 8q7QwYyj64ZpWdacZuond3YK2isLpatTNEFeo8A18eVTdl3JNYw8rOSuOf/KF8QZQgAw DI9Lywlyn8DyfmDDrr7S5qAn9Xf8r1kZYKPKHIzJDMbeRmG/6D62UcgSOVDSuHgaqOjS 46vg== 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=YDD8AKO2hwLZeCjZwKKM5uCY10n51t2OVbGyoK51PNI=; b=E4A+NsyeZARf/9cx3ncQDAvQJZrUOfaL8HsXfLYKhMzsAcKtTdwCLSW8FxunBtS68S W62m3bL45w9fCzrwWy31WrkWHxI3jTEl2yGfvhmzqIFXE+YuIV+iBX7O3qq6S3QhTZ8L O+tApnlV9hKBhKU2snHO7a2dCtJ3k6nR5zb/fIOB8BkT8dl20bapTDwiTUaR6wp6jJrQ vjps6rwdGPz4w5PvZQswCwjvJ6q3GjJxUe/yrIiqWO592wCbzb5HscTaC5luJVeilbb1 Ux7UphzdUABj2oPMezkaJotdYv3ZPj/aWMKYo8T2/4mM9j1Y8MBFptfJTuJ7U7nxutPI zaKw== X-Gm-Message-State: AOAM53071CAyCh+gfyCKLkPwEuDM71iZYIWgtI0zu2Yc6v904ROKaIs8 qkADdS4gyDts05ZWl+Xx0Gg= X-Google-Smtp-Source: ABdhPJyRnIf2o+EsMHqs1wwCuTq3PA6MHw12A4vwFStZqiREykSofWcZOn+2X4R8GHnrTO4hvxUoeA== X-Received: by 2002:a17:90a:e005:: with SMTP id u5mr7887650pjy.64.1607161268045; Sat, 05 Dec 2020 01:41:08 -0800 (PST) Received: from localhost ([2409:10:2e40:5100:6e29:95ff:fe2d:8f34]) by smtp.gmail.com with ESMTPSA id a5sm7569714pfg.140.2020.12.05.01.41.06 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 05 Dec 2020 01:41:07 -0800 (PST) Date: Sat, 5 Dec 2020 18:41:05 +0900 From: Sergey Senozhatsky To: Petr Mladek Cc: John Ogness , Sergey Senozhatsky , Sergey Senozhatsky , Steven Rostedt , Linus Torvalds , Greg Kroah-Hartman , Thomas Gleixner , linux-kernel@vger.kernel.org Subject: Re: recursion handling: Re: [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 (20/12/04 17:10), Petr Mladek wrote: > > One reason is the use of per-cpu variables. Alternative solution would > be to store printk_context into task_struct. We can keep per-CPU, disable preemption and have counters for every context (task, soft/hard irq, NMI). Shouldn't be a problem vprintk_emit() { preempt_disable() vprintk_store() preempt_enable() preempt_disable() console_unlock() preempt_enable() } vprintk_store() is a small fraction of console_unlock() time wise. -ss