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=-6.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,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 89B32C47082 for ; Tue, 1 Jun 2021 02:55:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 60B8A61186 for ; Tue, 1 Jun 2021 02:55:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232691AbhFAC5J (ORCPT ); Mon, 31 May 2021 22:57:09 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38658 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232268AbhFAC5E (ORCPT ); Mon, 31 May 2021 22:57:04 -0400 Received: from mail-pl1-x62e.google.com (mail-pl1-x62e.google.com [IPv6:2607:f8b0:4864:20::62e]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 89C83C061574 for ; Mon, 31 May 2021 19:55:24 -0700 (PDT) Received: by mail-pl1-x62e.google.com with SMTP id c13so1169327plz.0 for ; Mon, 31 May 2021 19:55:24 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=v3pohhDIzpTNGTaLw5FGOawbaRYby4i5Jggmf7n1XFo=; b=cDKZ7nrGg3SitOakQBGpVL1BFbEU6GaUR6pfRuOVyDbFDHTNgzjlEv9pGLJ6tQebx1 TvR4V7ARWr0D2ue6Vo1GzPXNBXAzRwVuTpyqLCLDFnqx+5pRQ6h8JR1Opa7ywKjmezTt 230z8WSKDLkL9v0juswaumkv0c+9iriSK8Mw8= 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=v3pohhDIzpTNGTaLw5FGOawbaRYby4i5Jggmf7n1XFo=; b=Yq7qisqUMY9YBvv7shJb9E5kc0UDfSSAVn+CSDNgyONtvW1x/h55C2gyBnkdHcY6eZ u9YsIgm2ocPxuxW0O7gbFJNZn2IszNy9frvddiQJJ+IEo0AGvAv1p5js9RhrPl8ySweC Mkc86/lVa77P9UugA1/9TseWYOJc0FxD/fSqwX7eOu6LdX+9fyL4XVKZq5j6IIKrvu/n 870mEnRlaagW2zLMR0Nier0cp6sEdEKBV3s4U1YHYT4uhw3/L8R4u9mFxkTtjk0vdUuV rG/PFPmrQtp+QhgFc6SVVTIGi0j7C0gQ6lSlahMhoXwjGcoEZxiFaJ67z0gMKOnMgkMi iv2Q== X-Gm-Message-State: AOAM530dzRfsbbYowFN6AYoqyaz98P6wW1l6C1GOWXAuzfwxrn1dMre4 PDEverPRszUeDu8BMYC0Cpg2oQ== X-Google-Smtp-Source: ABdhPJyHKfUsqE0m1JFGzAh6859rIZJIGXcyAHz3mDfWY6H7A9aRMVriVM16UsBMMvAhPOcRZnl2Fw== X-Received: by 2002:a17:90b:603:: with SMTP id gb3mr2237595pjb.118.1622516124107; Mon, 31 May 2021 19:55:24 -0700 (PDT) Received: from google.com ([2409:10:2e40:5100:3d42:f77e:d3ba:9a24]) by smtp.gmail.com with ESMTPSA id y20sm11868451pfn.164.2021.05.31.19.55.20 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 31 May 2021 19:55:23 -0700 (PDT) Date: Tue, 1 Jun 2021 11:55:17 +0900 From: Sergey Senozhatsky To: John Ogness Cc: Petr Mladek , Steven Rostedt , Thomas Gleixner , linux-kernel@vger.kernel.org, Sergey Senozhatsky , Andrew Morton , Stephen Rothwell , Dmitry Safonov <0x7f454c46@gmail.com>, Valentin Schneider , Daniel Bristot de Oliveira , Peter Zijlstra , Stephen Boyd , Alexander Potapenko , "Paul E. McKenney" Subject: Re: [PATCH next v1 1/2] dump_stack: move cpu lock to printk.c Message-ID: References: <20210531162051.2325-1-john.ogness@linutronix.de> <20210531162051.2325-2-john.ogness@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210531162051.2325-2-john.ogness@linutronix.de> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On (21/05/31 18:20), John Ogness wrote: > +void printk_cpu_lock(unsigned int *cpu_store, unsigned long *flags) > +{ > + unsigned int cpu; > + > + for (;;) { > + cpu = get_cpu(); > + > + *cpu_store = atomic_read(&printk_cpulock_owner); > + > + if (*cpu_store == -1) { > + local_irq_save(*flags); Is there any particular reason this does preempt_disable(); cpu = smp_processor_id(); local_irq_safe(); instead of local_irq_safe(); cpu = raw_smp_processor_id(); ?