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 53FFEC433FE for ; Wed, 9 Dec 2020 09:22:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0ECD1238EB for ; Wed, 9 Dec 2020 09:22:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729068AbgLIJWs (ORCPT ); Wed, 9 Dec 2020 04:22:48 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45454 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728703AbgLIJWr (ORCPT ); Wed, 9 Dec 2020 04:22:47 -0500 Received: from mail-pf1-x444.google.com (mail-pf1-x444.google.com [IPv6:2607:f8b0:4864:20::444]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A20F7C0613CF for ; Wed, 9 Dec 2020 01:22:07 -0800 (PST) Received: by mail-pf1-x444.google.com with SMTP id c79so634909pfc.2 for ; Wed, 09 Dec 2020 01:22:07 -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=lJ/NDJbgWxcT6fOKhdSAr+cmsq+iCmYq+jJ18WX01uM=; b=q4DFmtZmDIeK7nwfYx25OR1+aH2qoW24T+oe6su3FMSA9/oU6eB5lElVij6YaLzIDy bPeeEaJoK/BMnOsivoj2a0IY0WUKPgzofs5DHDEqXLgIAg/leBQNRwsUIc3Z6tMseXAI yP02oU8PHxkmr+aHihvxvcahuJTggr+8COCyG+jypXD/xxgG52mKgTKMdk4M3PLV1zN1 QgLX3RGoPAkZjf8VdII79LTEMf3Lho4o3mXkiQgMpSNOiaR0uxL6ShBcCJsz8nv/shsL /EOlFd5s60KF8/fyjix6MUZ+TMQnLsOPqqShi0ppfiQNwpgmVgsv0Hf5MW+m3ok7915a E2Sg== 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=lJ/NDJbgWxcT6fOKhdSAr+cmsq+iCmYq+jJ18WX01uM=; b=aRUvzXLqy97UOk8q/W9xv1nEGMKujhJHxxVa0M76SPlVtZ8whfSZyvaKIm2UrJnIGG Rw0q2CJiNr1phxY9visTLrwi0n7/GybEB0ma7IvcQqd6dEejBK1wgTwKKiDHMLvFWJdz Lr/0jHE0IcvyKgZqYIw6OUBwpuhSMA6BV0OHDXtFB3Tyo5wtSAIXXUaGpKWmab5h8VaC YjpJDAA6PR844UXG4ANuQAPsoieCS3wu8Qwm1qcoW+YiNn6KQ+/HtAWj0c8XpFmDtuyn h1CxQEhUe66bMfYiFyuP53RoZIO3NbsXnDRGEqeR0OeYlvfbXFymgapY2WV9YDFUYSzb sT1g== X-Gm-Message-State: AOAM533hu6tYZFlGwhTB3SxNoVkts6X0XN8Vyya5frYZcsZlmBppoqVd f5Ze8we/YdBH67spRBHKpd8= X-Google-Smtp-Source: ABdhPJynHp+3TusYEjZjW6pvV7nVcsoGw/4RRSwuBIAQBzpPsUc3f8BKUyCmed/dGJbHCN03pECF8A== X-Received: by 2002:a62:f901:0:b029:160:b5d:fc40 with SMTP id o1-20020a62f9010000b02901600b5dfc40mr1428247pfh.55.1607505727285; Wed, 09 Dec 2020 01:22:07 -0800 (PST) Received: from localhost ([2401:fa00:8f:203:a6ae:11ff:fe11:4b46]) by smtp.gmail.com with ESMTPSA id 188sm1711319pfd.188.2020.12.09.01.22.05 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 09 Dec 2020 01:22:06 -0800 (PST) Date: Wed, 9 Dec 2020 18:22:04 +0900 From: Sergey Senozhatsky To: Peter Zijlstra Cc: John Ogness , Sergey Senozhatsky , Petr Mladek , Sergey Senozhatsky , Steven Rostedt , Linus Torvalds , Greg Kroah-Hartman , Thomas Gleixner , linux-kernel@vger.kernel.org Subject: Re: [PATCH next v2 2/3] printk: change @clear_seq to atomic64_t Message-ID: <20201209092204.GD1667627@google.com> References: <20201201205341.3871-1-john.ogness@linutronix.de> <20201201205341.3871-3-john.ogness@linutronix.de> <875z5c9bhn.fsf@jogness.linutronix.de> <20201209081623.GI2414@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201209081623.GI2414@hirez.programming.kicks-ass.net> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On (20/12/09 09:16), Peter Zijlstra wrote: > On Tue, Dec 08, 2020 at 11:36:44PM +0106, John Ogness wrote: > > For the state variable we chose atomic_long_t instead of atomic64_t for > > this reason. atomic_long_t operations are available atomically on all > > architectures. > > Please put on your eye cancer gear and inspect the atomic implementation > of PA-RISC, Sparc32, feh, I forgot who else. > > Those SMP capable architectures are gifted with just one XCHG like > atomic instruction :/ Anyway, as said in the other email, they also > don't have NMIs so it mostly works. Hmm, wow. OK, I definitely want to look further. When some CONFIG_DEBUG_FOO_BAR code wants to pr_err from prb->atomic_op on those archs then we deadlock in printk once again? -ss