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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 16680C433EF for ; Tue, 5 Oct 2021 12:03:54 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id A3BF361502 for ; Tue, 5 Oct 2021 12:03:53 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org A3BF361502 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvack.org Received: by kanga.kvack.org (Postfix) id 3D8F26B006C; Tue, 5 Oct 2021 08:03:53 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 361CE6B0071; Tue, 5 Oct 2021 08:03:53 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 22A42900002; Tue, 5 Oct 2021 08:03:53 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0211.hostedemail.com [216.40.44.211]) by kanga.kvack.org (Postfix) with ESMTP id 135D26B006C for ; Tue, 5 Oct 2021 08:03:53 -0400 (EDT) Received: from smtpin11.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id C0BA21802F4A3 for ; Tue, 5 Oct 2021 12:03:52 +0000 (UTC) X-FDA: 78662249904.11.E51CC27 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) by imf15.hostedemail.com (Postfix) with ESMTP id 0C448D0004B4 for ; Tue, 5 Oct 2021 12:03:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=ssIz8dxHAZ6IED8P8Bx3CPoq2/dqQqF2DGl8wwvM3UU=; b=ugZGH/+jwI8TlL3iHvlwL6thJV LBKF0ZKvz9k7Pc22sM90mPiDJfgEV3XpkyRZJeATMt9AbXFhq5MRfjCxu8lDVzXdET+XdAUjHVTXF hVy99snz4XjdpFWzoLwKub+8tJSzNPQ91qbFgEe+8MI6bjHiF51C0bQCybqlIS57h6taO4QRFyrMi mCMgTZhhaWewxelrfkJhutOrsrK8y/5rHSYrPHf075uEkdmlNm6xmQ5pAzMuIPWWpyqDpCJ7mYUU3 wu1bbrsU6dH9yNYEwMgfSigG0uDuEiCyqTQR/y3cJFgrZ1gAIk2tJFazwxQ9V8RGOnpE+x9+KNCS9 XX6RRR4A==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1mXj9c-000PjY-SI; Tue, 05 Oct 2021 12:02:51 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 4732430026F; Tue, 5 Oct 2021 14:02:40 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 27D732026A8AF; Tue, 5 Oct 2021 14:02:40 +0200 (CEST) Date: Tue, 5 Oct 2021 14:02:40 +0200 From: Peter Zijlstra To: Marco Elver Cc: "Paul E . McKenney" , Alexander Potapenko , Boqun Feng , Borislav Petkov , Dmitry Vyukov , Ingo Molnar , Josh Poimboeuf , Mark Rutland , Thomas Gleixner , Waiman Long , Will Deacon , kasan-dev@googlegroups.com, linux-arch@vger.kernel.org, linux-doc@vger.kernel.org, linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, x86@kernel.org Subject: Re: [PATCH -rcu/kcsan 16/23] locking/atomics, kcsan: Add instrumentation for barriers Message-ID: References: <20211005105905.1994700-1-elver@google.com> <20211005105905.1994700-17-elver@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20211005105905.1994700-17-elver@google.com> X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 0C448D0004B4 X-Stat-Signature: oic75pyy33g9ehzepawxgck9jok1mieg Authentication-Results: imf15.hostedemail.com; dkim=pass header.d=infradead.org header.s=casper.20170209 header.b="ugZGH/+j"; dmarc=none; spf=none (imf15.hostedemail.com: domain of peterz@infradead.org has no SPF policy when checking 90.155.50.34) smtp.mailfrom=peterz@infradead.org X-HE-Tag: 1633435431-556004 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Tue, Oct 05, 2021 at 12:58:58PM +0200, Marco Elver wrote: > @@ -59,6 +60,7 @@ atomic_add(int i, atomic_t *v) > static __always_inline int > atomic_add_return(int i, atomic_t *v) > { > + kcsan_mb(); > instrument_atomic_read_write(v, sizeof(*v)); > return arch_atomic_add_return(i, v); > } This and others,.. is this actually correct? Should that not be something like: kscan_mb(); instrument_atomic_read_write(...); ret = arch_atomic_add_return(i, v); kcsan_mb(); return ret; ?