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=-3.9 required=3.0 tests=BAYES_00,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 2BF5BC433E1 for ; Wed, 19 Aug 2020 07:11:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id ECF8D20738 for ; Wed, 19 Aug 2020 07:11:18 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="sQPs0i7L"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="C5Ml3HGE" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727829AbgHSHLR (ORCPT ); Wed, 19 Aug 2020 03:11:17 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38878 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727069AbgHSHK6 (ORCPT ); Wed, 19 Aug 2020 03:10:58 -0400 Received: from galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C5987C061389 for ; Wed, 19 Aug 2020 00:00:25 -0700 (PDT) Date: Wed, 19 Aug 2020 09:00:22 +0200 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1597820424; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=B1zUwx2pLAnRGU5u67tZdctm2NefQ1yx0G/oZpzGA/8=; b=sQPs0i7LK+fy6qwgYxr3ZQshmtbaJogx7ElIj7A1Ei90S93UsHrRpEHYERLfd9Kt/LZzZZ 3J1gssXj4KuwzRoZqd7IrVywsvod2RR8CvCvRuyJEyh2ZcZRvEDp9dCn5Sh3jkIfYz3BEw /zt+Ymn4y+ehCPu5WgK1uA2x532THoryxNkKtl1bEbZ/K1dvym/6rpVl4lvmAo7QkvS/1Z AWo1EZHT3f4+Rt6xVC1lx76LUTWKZYMLtDWf46VJXWeoLfAaC597TrbmHHbM91nNkInjA8 DNF+i2t4AKaJgHVi2sgP7fCib/Ommw2atrJFmZToN87Mpp33i9nh6KeMBNtGMA== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1597820424; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=B1zUwx2pLAnRGU5u67tZdctm2NefQ1yx0G/oZpzGA/8=; b=C5Ml3HGENuPGyezU4zCjbew0sp8tOT83GfPlQLcX2Za42WXLxCVskhiVhiP5GuCT6FFkun uju+b4jflL7Z27Cw== From: Sebastian Andrzej Siewior To: Guenter Roeck Cc: Valdis =?utf-8?Q?Kl=C4=93tnieks?= , Mark Starovoytov , Igor Russkikh , "David S. Miller" , Greg KH , "Ahmed S. Darwish" , linux-kernel@vger.kernel.org, mingo@redhat.com, paulmck@kernel.org, peterz@infradead.org, rostedt@goodmis.org, tglx@linutronix.de, will@kernel.org Subject: Re: [PATCH] Revert "seqlock: lockdep assert non-preemptibility on seqcount_t write" Message-ID: <20200819070022.semyxepadnvtmtcr@linutronix.de> References: <20200810085954.GA1591892@kroah.com> <20200810095428.2602276-1-a.darwish@linutronix.de> <20200810100502.GA2406768@kroah.com> <169454.1597791078@turing-police> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2020-08-18 17:56:49 [-0700], Guenter Roeck wrote: > Nice catch. FWIW, there is no obvious reason why this would need to be atomic. > The calling code does not set a lock, meaning there can be two (or more) > callers entering this code. Weird, especially since the code looks like it > would actually need a mutex to work correctly. It might be interesting to > see what happens if there are, say, half a dozen scripts/processes trying > to read the hwmon attribute introduced by this patch at the same time. => https://lkml.kernel.org/r/20200818161439.3dkf6jzp3vuwmvvh@linutronix.de > Guenter Sebastian